| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
,
*
Department of Microbiology and Immunology,
Department of Infectious Disease Control,
Institute of Laboratory Animals, and
§
Department of Pediatric Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women’s Medical College, Tokyo, Japan
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
ß complex arise from immature CD4-
CD8- CD3- cells through a process of positive
or negative selection and differentiation, and then migrate to the
periphery, where they perform their role as immunocytes. It is
currently not clear whether these migrating thymic SP T cells have a
functional immunocompetence comparable to that of adult peripheral
blood (APB) T cells, or whether they continue to mature during
migration to acquire full reactivity to antigenic stimulation. Thymic
SP, cord blood (CB), and APB T cells variously express differentiation
molecules such as CD38 and CD45 (1, 2, 3, 4, 5), indicating that the phenotype
of T cells does change during migration from the thymus to the
periphery. We recently found that CB T cells are susceptible to anergy induction upon stimulation with a superantigen (sAg), toxic shock syndrome toxin-1 (TSST-1) (6). A high proportion of TSST-1-induced CB T cell blast preparations produced only small amounts of IL-2 and IL-4 after restimulation with TSST-1, compared with APB T cell blast preparations. Similar results have been obtained by others in experiments examining the alloantigen reactivity of CB T cells (7). CD45RO+ T cells that were found to be relatively abundant in peripheral T cells from premature births were unresponsive to stimulation with anti-CD2 and anti-CD3 mAbs (8), suggesting functional immaturity of the fetal peripheral T cells. We believe that these findings may reflect the functional immaturity of newly migrating, infant thymic SP T cells. This idea suggests that the thymic CD1a- CD4+ T cells, which are thought to be in a final stage of functional maturation in the thymus (1, 5), are much more susceptible to anergy induction than are CB CD4+ T cells. Recently, one group has reported that thymic T cells are susceptible to anergy induction by sAg (9).
In the present study, we compared the susceptibility to anergy induction of thymic CD1a- CD4+ and CB CD4+ T cells. The results showed that thymic CD1a- CD4+ T cells are much more susceptible to the TSST-1-induced anergy induction than are CB CD4+ T cells, indicating that thymic CD1a- CD4+ T cells are markedly less functionally mature than CB CD4+ T cells. These results suggest that thymic T cells undergo post-athymic maturation as they migrate to the periphery, which is necessary for acquisition of full reactivity to antigenic stimulation.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
TSST-1 was obtained from the culture fluid of Staphylococcus aureus FRI1169 by a combination of SP Sephadex C25, PBE94 chromatofocusing, and Sephacryl S200 as reported previously (10). PMA, calcium ionophore A23187 (IONO), and 4',6-diamidino-2-phenylindole were obtained from Sigma Chemical Co. (St. Louis, MO). Etoposide was obtained from Wako Pure Chemical Co. (Tokyo, Japan). The RPMI 1640 culture medium used contained 100 µg/ml streptomycin, 100 U/ml penicillin, 10% FCS, and 5 x 10-5 M 2-ME. Recombinant IL-2 was provided by Takeda Chemical Industries (Kyoto, Japan).
Monoclonal Abs
I2C3 (anti-HLA-DR/DP) and Nu Ts/c (anti-CD8) were described previously (11). FITC-conjugated SK3 (anti-CD4), PE-conjugated SK1 (anti-CD8), and FITC- or PE-conjugated SK7 (anti-CD3) were purchased from Becton Dickinson (Mountain View, CA). RD1-conjugated mAbs, I2 (anti-DR), SFCI19 (anti-CD1a), and LS198-4-3 (anti-CD38) were purchased from Coulter Immunology (Hialeah, FL). Biotin-conjugated E22E7.2 (anti-Vß2) and FITC-conjugated UCHL.1 (anti-CD45RO) were purchased from Immunotech S.A. (Cedex, France) and Dakopatts (Glostrup, Denmark), respectively. PE-conjugated M-A251 (anti-CD25) and PE-conjugated streptavidin were purchased from PharMingen (San Diego, CA) and Becton Dickinson (Mountain View, CA), respectively. Hybridoma cell lines, OKT6 (anti-CD1a) and OKT10 (anti-CD38), were purchased from American Type Culture Collection (Rockville, MD) and used as ascites fluid.
Preparation of APB and CB T cells
The procedures for preparation of human lymphoid cell fractions were described previously (12). Briefly, APB mononuclear cells were isolated from peripheral blood of healthy adult donors by Ficoll-Conray density gradient centrifugation. Whole T cell preparations were obtained using the SRBC rosette method. To obtain CD4+ T cell preparations, whole T cells were treated with mAb Nu Ts/c (anti-CD8) and I2C3 (anti-DR/DP), washed, and then mixed with a 10-fold excess of anti-mouse IgG Ab-coupled magnetic beads (Dynabeads, Dynal, Oslo, Norway). The mixtures were kept on ice for 30 min, unbound and bound cells were separated by magnet, and unbound cells were collected. The APB CD4+ T cell preparations obtained were analyzed by flow cytometry: CD3+ cells (88.9 ± 1.2%) contained CD4+ T cells (92.1 ± 1.1%), CD8+ T cells (<2%), HLA-DR+ T cells (<3%), and CD1a+ T cells (<1%). CB mononuclear cells were isolated from cord blood of neonates with a gestational age of 38 to 40 wk. The procedures for whole and CB CD4+ T cell preparations were the same as those for APB cell preparations; CD3+ cells (80.7 ± 5.0%) of CB CD4+ T cell preparations contained CD4+ T cells (91.2 ± 2.0%), CD8+ T cells (<1%), HLA-DR+ T cells (<1%), and CD1a+ T cells (<1%).
Preparation of thymic cells
Single-cell suspensions were obtained from thymus fragments dissected from donors ranging from 3 to 24 yr of age during corrective cardiac surgery. To enrich the suspension for mature thymic cells, agglutination with PNA was used as described previously (13). PNA-nonaggregated thymic T cell preparations contained two- to fourfold more thymic SP cells than whole thymic cells. To obtain preparations of thymic CD4+ T cells containing both CD1a+ and CD1a- T cells, and thymic CD1a- CD4+ T cells, PNA-nonaggregated thymic T cells were treated with a combination of mAbs Nu Ts/c and I2C3 and with a combination of mAbs Nu Ts/c, I2C3, and OKT6 (anti-CD1a), respectively. Cells that reacted with those mAbs were removed using anti-mouse IgG Ab-coupled magnetic beads. Analysis of thymic CD1a- CD4+ T cell preparations showed that 76.1 ± 3.6% of the cells were CD3+ cells; CD3+ cells contained CD4+ T cells (91.6 ± 1.2%), CD8+ T cells (<2%), HLA-DR+ T cells (<3%), CD1a+ T cells (<1%), and CD4+ CD8+ T cells (<1%). Thymic CD4+ T cell preparations showed similar phenotypes to the thymic CD1a- CD4+ T cell preparations except that they contained CD1a+ T cells (37.1 ± 3.6%).
Preparation of TSST-1-induced T cell blasts
TSST-1-induced T cell blasts were obtained as described previously (6, 14). Briefly, thymic T cells (PNA- whole, CD4+, and CD1a- CD4+ T cells), CB T cells (whole and CD4+ T cells), and APB T cells (whole and CD4+ T cells) were stimulated with 10 ng of TSST-1/ml in the presence of DR+ L cells (8124) as accessory cells (AC) for 3 days. Recovered cells were subjected to Percoll (density = 1.068) centrifugation. The large lymphoblasts obtained at the interface of the culture medium and Percoll were expanded by incubation with 100 U of rIL-2/ml for 2 days in two cycles. Recovered cells were subjected to Percoll centrifugation (densities = 1.055 and 1.068). T cell blasts were obtained at the interface between densities 1.055 and 1.068. T cell blasts obtained from PNA- thymic T cells, whole CB T cells, and whole APB T cells were further purified to CD4+ T cell blasts by a combination of mAb NU Ts/c and anti-mouse IgG Ab-coupled magnetic beads. DR+ L cells (8124) were irradiated at 3000 rad with an x-ray irradiator and treated with 50 µg of mitomycin C/ml for 30 min at 37°C before use as AC.
Assay for proliferative responses
To determine the proliferative response to TSST-1, T cells were stimulated with TSST-1 in 0.2-ml volumes in triplicate in flat-bottom 96-well microplates (Corning Glass Works, Corning, NY) in the presence of DR+ L cells for 72 h. To determine the proliferative response to IL-2, T cell blasts were stimulated with rIL-2 in triplicate in round-bottom 96-well plates (Corning Glass Works) in the absence of AC for 48 h. Cultures were pulsed with 0.5 µCi (18.5 kBq) of [3H]TdR for the last 16 h of the culture period. Data are presented as the average counts per minute and SE of triplicate determinations.
Assay for production of IL-2 and IL-4
In the production of IL-2 and IL-4, T cells were stimulated with TSST-1 in the presence of DR+ L cells for varying periods or by a combination of PMA (10 ng/ml) and IONO (0.4 µM) in the absence of AC for 8 h in 1-ml volumes in 48-well culture plates (Corning Glass Works). IL-2 activity in the culture supernatants was determined using IL-2-dependent CTLL-2 cells, as reported previously (15). Data are presented as units of IL-2 per ml. The amounts of IL-4 in the culture supernatants were determined by the enzyme-amplified sensitivity immunoassay system (Medgenix Diagnostics, Fleurus, Belgium), according to the manufacturer’s instructions. Data are presented as picograms of IL-4 per ml.
Flow cytometric analysis
For examination of expression of CD3 vs CD4, CD3 vs CD8, CD3 vs Vß2, CD3 vs CD25, CD3 vs CD45RO, CD3 vs CD1a, CD3 vs HLA-DR, and CD3 vs CD38 in T cell preparations, T cells were stained with several combinations of the appropriate PE-, RD1-, and FITC-conjugated mAbs and examined by two-color flow cytometric analysis using the flow cytometer EPICS CS (Coulter Electronics) as described previously (6). All procedures for cell staining were conducted on ice.
Assay for DNA fragmentation
T cell blasts were examined for DNA fragmentation before and after the induction of apoptotic cell death as described previously (16). Each cell suspension (2 x 106) was dispensed into two tubes and centrifuged. The cell pellets were lysed in 100 µl of 5 mM Tris buffer containing 1 mM EDTA and 0.5% Triton X-100 overnight at 4°C. One of the two tubes was centrifuged at 27,000 x g for 20 min to separate the fragmented DNA from the unfragmented DNA. The supernatant obtained and the whole lysate in the other tube were sonicated for 2 min to break up chromatin DNA. To 2 ml of 10 mM Tris buffer containing 500 ng/ml 4',6-diamidino-2-phenylindole and 100 mM NaCl, 20 µl of the sample was added, and the fluorescence intensity was measured at 454 nm with excitation at 362 nm. The percentage of fragmented DNA was defined as the ratio of the DNA content in the supernatant to that in the whole lysate. The data represent the mean and SE of three samples.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Thymic, CB, and APB CD4+ T cells were initially stimulated with TSST-1 in the presence of HLA-DR+ L cells and examined for a proliferative response and IL-2 production to determine the optimal conditions for stimulation and for obtaining T cell blasts. We used two preparations of thymic CD4+ T cells, one that contained both CD1a+ and CD1a- fractions and one that contained only a CD1a- fraction. The CD1a- SP T cells were in a final stage of maturation in the thymus (1, 5).
The results of several experiments investigating IL-2 production are
summarized in Table I
. All preparations
of APB CD4+ T cells exhibited substantial IL-2 production
in response to TSST-1. All preparations of thymic CD1a-
CD4+ T cells also produced IL-2, but at a much lower level
than those in APB CD4+ T cells over the doses of TSST-1
examined. The response of thymic CD4+ T cells containing
both CD1a+ and CD1a- fractions was only
marginal, as expected. The response of CB CD4+ T cells was
at an intermediate level between those of thymic CD1a- and
APB CD4+ T cells. We could not detect any IL-4 production
in any T cell preparation examined here (data not shown).
|
. The response of thymic
CD4+ T cells containing both CD1a+ and
CD1a- T cells was lower than those of the other two T cell
preparations. More T cell blasts were generated 3 days after
stimulation with TSST-1 in thymic CD1a- CD4+ T
cells than in thymic CD4+ T cells containing both
CD1a- and CD1a+ fractions (data not shown).
These results indicate that the T cells reactive to TSST-1 in the
thymocytes are mainly in the CD1a- CD4+ T cell
fraction. In subsequent experiments thymic, CB, and APB T cells were
stimulated with 10 ng/ml TSST-1 for 3 days to induce blast formation of
TSST-1-reactive T cells. DR+ L cells were used as AC in all
experiments to exclude the possibility that the immunologic
reactivities of T cells were influenced by AC present in the original
organs.
|
We examined the immunologic phenotypes of TSST-1-induced thymic,
CB, and APB CD4+ T cell blasts. Thymic
PNA- or CD1a- CD4+ T cells, CB
whole or CD4+ T cells, and APB whole or CD4+ T
cells from several distinct donors were stimulated with 10 ng/ml TSST-1
for 3 days in the presence of DR+ L cells. Large
lymphoblasts were collected and expanded in the presence of rIL-2 for 4
days. T cell blasts obtained from thymic PNA-, whole CB,
and APB T cells were purified into CD4+ T cell blasts as
described in Materials and Methods. The results are
summarized in Table II, and typical flow
cytometry histograms for one of several independent experiments are
presented in Figure 2. The percentage of
TCR Vß2+ T cells that composed the major TSST-1-reactive
fraction (17) was markedly increased from around 8% in the
unstimulated state to around 80% in all thymic, CB, and APB
CD4+ T cell blasts, indicating that all thymic, CB, and APB
CD4+ T cell blasts contained sufficient TSST-1-reactive T
cells. No CD1a+ fraction was detected in any of the cell
fractions. Expression of CD25 was higher in thymic and CB
CD4+ T cell blasts than in APB CD4+ T cell
blasts. Expression of the DR molecule was much higher in APB
CD4+ T cell blasts than in thymic and CB T cell blasts.
|
|
The TSST-1-induced thymic, CB, and APB CD4+ T
cell blasts obtained as described above were restimulated with varying
doses of TSST-1 for varying periods in the presence of DR+
L cells and were examined for production of IL-2. The results are
summarized in Table III. All APB
CD4+ T cell blast preparations exhibited substantial IL-2
production after restimulation with 1 ng/ml or more of TSST-1. All
thymic CD4+ T cell blast preparations exhibited low
responses, reaching a maximum that was 5% of the APB CD4+
T cell blast response over the full range of TSST-1 doses and culture
periods examined. In contrast, the responses of CB CD4+ T
cell blasts varied among different preparations as shown previously
(6). At 1 ng/ml TSST-1, all CB T cell blast preparations exhibited
negligible or low responses. At higher TSST-1 doses (10–100 ng/ml),
two preparations also exhibited quite low responses compared with those
of APB T cell blasts (Table III, Expt. 5). The other four preparations
exhibited more marked responses, ranging from 30 to 60% of the APB T
cell blast responses (Table III, Expt. 4 and 6).
|
TSST-1 stimulation does not convert thymic CD4+ T cells to the Th2 phenotype
CD4+ T cells are divided into two functional
phenotypes: the Th1 type, which preferentially produces IL-2 and
IFN-
, and the Th2 type, which preferentially produces IL-4, IL-5,
and IL-10 (18, 19). Recently, it was found that cloned murine
CD4+ T cell lines bearing the Th0 phenotype, which have the
capacity to convert to either the Th1 or the Th2 type, preferentially
converted to the Th2 type following several kinds of stimuli, including
specific Ags (20). Based on these results, most of the thymic
CD4+ T cell blasts in the present study may be of the Th2
phenotype. Previously, we showed that TSST-1-induced CB T cell blasts
showed little or no IL-4 production following restimulation with TSST-1
(6), suggesting that the above possibility is unlikely. To address this
question, TSST-1-induced thymic CD4+ T cell blasts were
examined for IL-4 production after restimulation with TSST-1.
Two of the four thymic CD4+ T cell blast preparations
(Table IV, Expt. 2 and 4) exhibited no
IL-4 production, while the other two (Expt. 1 and 3) exhibited only
marginal responses, and APB CD4+ T cell blasts produced
marked IL-4 production. As expected, these results indicated that
conversion to the Th2 phenotype did not occur in the thymic
CD4+ T cell blasts.
|
TSST-1-induced thymic CD4+ T cell blasts show a reduced response to stimulation with IL-2 and a combination of PMA and IONO
The TSST-1-induced thymic, CB, and APB CD4+ T
cell blasts were initially stimulated with 100 U/ml rIL-2 for 48 h
and tested for proliferative responses (Table V). All APB CD4+ T cell blast
preparations exhibited marked proliferative responses. In contrast, the
thymic CD4+ T cell blasts exhibited varied, although
generally low, responses in different preparations, ranging from
marginal to 40% of the APB CD4+ T cell blast responses
(Table V, Expt. 3). Nine of 10 CB CD4+ T cell blast
preparations exhibited slightly lower, but comparable, levels of
response to the APB CD4+ T cell blasts, and the other
preparation (Table V, Expt. 2) exhibited a low response.
|
). All CB CD4+ T cell blast
preparations also exhibited low responses, but these were higher than
those of the thymic CD4+ T cell blasts.
|
To confirm that the TSST-1-induced thymic
CD4+ T cell blasts that showed minimal or no
reactivity to stimulation with rIL-2 and a combination of PMA and IONO
(Tables V and VI) were still alive, the extent of DNA fragmentation
before and after induction of apoptotic cell death was used as an
indicator of cell death. To induce apoptotic cell death, T cell blasts
were irradiated at 1000 rad and subsequently incubated for 5 h
(21) or were incubated for 5 h in the presence of etoposide, which
enhances programmed cell death (22). Both thymic and APB
CD4+ T cell blasts exhibited only marginal levels of DNA
fragmentation when examined before the induction of apoptotic cell
death, while both of them exhibited enhanced DNA fragmentation at
comparable levels after either treatment (Table VII). These results indicated that both
thymic and APB CD4+ T cell blasts remained alive soon after
harvest.
|
CD38 is generally expressed at a higher rate by thymic and CB T
cells than by APB T cells. We determined that 77% of thymic
CD1a- CD4+ T cells, 94% of CB
CD4+ T cells, and 20% of APB CD4+ T cells were
CD38+. The susceptibility of thymic CD1a- and
CB CD4+ T cells to anergy induction with TSST-1 may be
associated with the high incidence of CD38+ cells in the
two T cells mentioned above. To evaluate this possibility, APB
CD38+ and CD38- CD4+ T cells were
prepared and tested for susceptibility to anergy induction.
CD38+ and CD38- T cells depleted of HLA class
II+ T cells were also examined. These T cells were
stimulated with 10 ng/ml TSST-1 in the presence of DR+ L
cells for 3 days, and large lymphoblasts were collected and expanded
with rIL-2. The four T cell blast preparations were restimulated with
TSST-1 in the presence of DR+ L cells and tested for IL-2
production. IL-2 production was higher in CD4+ T cell
blasts derived from APB CD38+ T cells than in APB
CD38- T cells (Table VIII),
suggesting that this effect is unlikely to be associated with
CD38.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The TSST-1-induced thymic, CB, and APB CD4+ T cell blasts
were in markedly contrasting states with regard to the responsiveness
to Ag and nonspecific stimulation. All TSST-1-induced APB
CD4+ T cell blast preparations showed strong responses to
restimulation with TSST-1 and stimulation with rIL-2 or with a
combination of PMA and IONO. In contrast, all TSST-1-induced thymic
CD4+ T cell blast preparations exhibited little or no
production of IL-2 (Table III
) and IL-4 (Table IV) following
restimulation with TSST-1. These T cell blasts also exhibited little or
no responses to stimulation with rIL-2, with one exception (Table V),
and to the combination of PMA and IONO (Table VI). The TSST-1-induced
CB CD4+ T cell blasts exhibited varied responses ranging
from minimal to relatively high levels in different preparations after
three different stimulations. The facts that DNA fragmentation was
quite low in thymic CD4+ T cell blasts (Table VII), and
that thymic and CB CD4+ T cell blasts exhibited
TSST-1-mediated killing activity on Raji cells in low, but comparable,
levels to APB CD4+ T cell blasts (data not shown) indicate
that the TSST-1-induced thymic CD4+ T cell blasts analyzed
in the present study remained alive. The results indicated that
TSST-1-induced thymic CD4+ T cell blasts are in a deeply
anergic state, while CB CD4+ T cell blasts are varied in
their anergy states in the different preparations, ranging from a high
to a minimal level. These observations indicate that thymic
CD1a- CD4+ T cells are markedly more
susceptible to anergy induction by TSST-1 than are CB CD4+
T cells.
There are several possible explanations for the susceptibility of
thymic and CB CD4+ T cells and the nonsusceptibility of APB
CD4+ T cells to anergy induction by sAg. We believe that
the most likely explanation is that their different reactions to
stimulation with TSST-1 are due to their inherent immunologic natures.
Most thymic CD1a- CD4+ and CB CD4+
T cells are CD38 positive, whereas a lower proportion of APB T cells
expresses CD38 (2, 3, 23, 24). As CD38+ T cells are
considered to be immature (25), they may be more susceptible to anergy
induction by sAg. This possibility is unlikely because APB
CD38+ CD4+ T cells are not susceptible to
anergy induction by TSST-1 (Table VIII). CD45RO- T cells,
which constitute the majority of CB T cells (6, 26), are considered
naive cells (25, 27), suggesting a high susceptibility of CB T cells to
anergy induction by sAg. This possibility is also unlikely because we
previously showed that APB CD45RO- T cells are not
susceptible to anergy induction with TSST-1 (6). These findings rule
out the possibility of any particular T cell fraction determining the
susceptibility or resistance to anergy induction in thymic, CB, and APB
T cells. In the present study we used DR+ L cells with high
AC activity in all cultures to exclude the possibility that the
susceptibility of thymic and CB T cells to anergy induction was due to
a defect in AC activity in these cells, which has been previously
suggested (28). Therefore, thymic CD1a- T cells appear to
remain in a functionally immature stage, and CB CD4+ T
cells are heterogeneous in maturational stages.
Human thymic CD1a+ T cells were reported to exhibit a high
proliferative response, at a level comparable to that of thymic
CD1a- T cells, to staphylococcal enterotoxin B (SEB) (9).
We found that the proliferative response and IL-2 production in whole
thymic CD4+ T cells were 50% or less of those in thymic
CD1a- CD4+ T cells (Fig. 1 and Table I). Since
whole thymic CD4+ T cells consisted of comparable
percentages of CD1a- and CD1a+ T cell
fractions (60 and 40%, respectively), it seems likely that the
positive responses observed in whole thymic CD4+ T cells
were mostly due to the responses of CD1a- CD4+
T cells. The results of the former group are in contrast with ours and
with those of another report that found that thymic SP
CD1a- T cells responded well to combined stimulation with
PHA and IL-2, while thymic SP CD1a+ T cells did not respond
(5). Currently, there are no available data to explain this
discrepancy. The former group also showed that unfractionated
thymocytes stimulated with SEB showed a marked proliferative response,
with a peak on day 3 of stimulation, and exhibited unresponsiveness
when restimulated with SEB on day 7 of the first stimulation by
addition of SEB to the original culture plates (9). Although they did
not present data on the responses of APB T cells, their report suggests
that anergy was induced by SEB-1 in thymic T cells.
It is still not clear where and when the thymic SP T cells undergo functional maturation after they leave the thymus. Studies introducing T cell transfer and thymectomy indicate that the peripheral T cell are renewed at the periphery without any output of T cells from the thymus (29, 30, 31). We believe that the peripheral lymphoid organs are the most plausible site for thymic SP T cell functional maturation after migration from the thymus. It was reported that thymic T cells exhibiting a morphologically mature type are generated in the medullary region of the thymus at the 17th gestational week (32). Provided that thymic SP T cells that migrated to the periphery at the 17th gestational week are included with the CB T cells as a functionally mature type, the duration of functional maturation of migrated thymic SP T cells is calculated to be about 20 wk, suggesting that the putative maturation would be as short as <20 wk. Recently, we observed that the peripheral blood T cells from a 1-yr-old infant with Kawasaki disease generated massive T cell blasts in response to TSST-1, and the T cell blasts obtained after expansion with rIL-2 exhibited an enhanced response to TSST-1 (unpublished observation), indicating that most peripheral T cells in this infant had already undergone maturation.
The findings of the present study could provide clues for understanding the immunologic state of thymic SP T cells in the late stage of maturation and their post-thymic maturation after migration to the periphery. The findings suggest that a large proportion of the peripheral T cells are still in an immature stage in newborn infants. We do not know the exact mechanism of the putative post-thymic maturation. A defect in this mechanism, however, would elicit serious immunodeficiency after birth. Examination of this issue would be important for the protection of newborn infants from infectious diseases.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
2 Address correspondence and reprint requests to Dr. Ken’ichi Imanishi, Department of Microbiology and Immunology, Tokyo Women’s Medical College, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162, Japan.
3 Abbreviations used in this paper: SP, single positive; CD4+, CD4 SP; CD8+, CD8 SP; APB, adult peripheral blood; CB, cord blood; sAg, superantigen; TSST-1, toxic shock syndrome toxin-1; IONO, calcium ionophore A23187; PE, phycoerythrin; PNA, peanut agglutinin; AC, accessory cell; SEB, staphylococcal enterotoxin B.
Received for publication June 2, 1997. Accepted for publication September 19, 1997.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  H. K. Ono, K. Omoe, K. Imanishi, Y. Iwakabe, D.-L. Hu, H. Kato, N. Saito, A. Nakane, T. Uchiyama, and K. Shinagawa Identification and Characterization of Two Novel Staphylococcal Enterotoxins, Types S and T Infect. Immun., November 1, 2008; 76(11): 4999 - 5005. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Nakagawa, K. Kushiya, I. Taneike, K. Imanishi, T. Uchiyama, and T. Yamamoto Specific Inhibitory Action of Anisodamine against a Staphylococcal Superantigenic Toxin, Toxic Shock Syndrome Toxin 1 (TSST-1), Leading to Down-Regulation of Cytokine Production and Blocking of TSST-1 Toxicity in Mice Clin. Vaccine Immunol., March 1, 2005; 12(3): 399 - 408. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Koyanagi, K.'i. Imanishi, Y. Arimura, H. Kato, J. Yagi, and T. Uchiyama Immunologic immaturity, but high IL-4 productivity, of murine neonatal thymic CD4 single-positive T cells in the last stage of maturation Int. Immunol., February 1, 2004; 16(2): 315 - 326. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Chen, M. Koyanagi, K. Fukada, K.'i. Imanishi, J. Yagi, H. Kato, T. Miyoshi-Akiyama, R. Zhang, K. Miwa, and T. Uchiyama Continuous Exposure of Mice to Superantigenic Toxins Induces a High-Level Protracted Expansion and an Immunological Memory in the Toxin-Reactive CD4+ T Cells J. Immunol., April 15, 2002; 168(8): 3817 - 3824. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Yagi, U. Dianzani, H. Kato, T. Okamoto, T. Katsurada, D. Buonfiglio, T. Miyoshi-Akiyama, and T. Uchiyama Identification of a New Type of Invariant V{alpha}14+ T Cells and Responsiveness to a Superantigen, Yersinia pseudotuberculosis- Derived Mitogen J. Immunol., September 15, 1999; 163(6): 3083 - 3091. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. P. Berzins, D. I. Godfrey, J. F. A. P. Miller, and R. L. Boyd A central role for thymic emigrants in peripheral T cell homeostasis PNAS, August 17, 1999; 96(17): 9787 - 9791. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Fujimaki, M. Iwashima, J. Yagi, H. Zhang, H. Yagi, K. Seo, Y. Imai, K.'i. Imanishi, and T. Uchiyama Functional Uncoupling of T-cell Receptor Engagement and Lck Activation in Anergic Human Thymic CD4+ T Cells J. Biol. Chem., May 11, 2001; 276(20): 17455 - 17460. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
), thymic
CD1a- CD4+ T cells (
), and APB
CD4+ T cells (
) (105 per well) were
stimulated in vitro with increasing doses of TSST-1 in the presence of
DR+ L cells (104 per well) for 3 days and
assayed for proliferative responses. Thymic CD4+ T cells
contained both CD1a+ and CD1a-
fractions.