HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Fujimoto, S. Articles by Sehon, A. H. Search for Related Content PubMed Articles by Fujimoto, S. Articles by Sehon, A. H.

Regulation of the Immune Response to Tumor Antigens

II. The Nature of Immunosuppressor Cells in Tumor-Bearing Hosts¹

From the Department of Immunology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, R3E OW3, Canada

Abstract

Immunosuppressor (IS) cells were found to be generated in tumor-bearing animals (TBA) within 24 hr after inoculation of tumor cells of the methylcholanthrene-induced Sarcoma 1509a and appeared to persist in the hosts as long as the tumor was progressing. However, IS cells disappeared with 5 days after extirpation of the tumor.

Increasing doses of thymus cells of TBA increased the degree of suppression of tumor rejection in immune syngeneic animals. Ten million thymus cells of TBA were capable of suppressing significantly the tumor rejection. The IS cells were detected in the thymuses, spleens, and draining lymph nodes, as well as in bone marrow of TBA, but could not be detected in the peripheral circulating blood. Since immunosuppressive activity of bone marrow cells from TBA was entirely abolished by the in vitro treatment of the cells with anti- serum and complement, the observed immunosuppression appears to be mediated by the T cell population.

Hydrocortisone treatment of TBA did not abolish the suppressive activity of the thymus or spleen cells of the treated TBA, thus suggesting that IS cells were cortisoneresistant.

The suppressive activity was found to be associated with cells of lowest density on centrifugation through a discontinuous density gradient of Ficoll. The results of this study, taken together with those presented in the preceding article, suggest that IS cells belong to a T cell subpopulation (immunosuppressor T cells). The relationships between immunosuppressor T cells and other T cell subpopulations, i.e., cytotoxic (effector) or helper (amplifier) T cells, remain to be elucidated in further experiments.

Footnotes

¹ This study was supported by grants from the Medical Research Council of Canada (MA4795), National Cancer Institute of Canada, and the National Institutes of Health (CA-13192), Bethesda, Maryland.

² Scholar of the Medical Research Council of Canada.

³ Fellow of the Medical Research Council of Canada.