PT  - JOURNAL ARTICLE
AU  - Tsokos, G C
AU  - Berger, M
AU  - Balow, J E
TI  - Modulation of human B cell immunoglobulin secretion by the C3b component of complement.
DP  - 1984 Feb 01
TA  - The Journal of Immunology
PG  - 622--626
VI  - 132
IP  - 2
4099  - http://www.jimmunol.org/content/132/2/622.short
4100  - http://www.jimmunol.org/content/132/2/622.full
SO  - J. Immunol.1984 Feb 01; 132
AB  - The human C3b component of complement was found to inhibit the differentiation of human B lymphocytes into immunoglobulin-secreting cells in vitro. Pokeweed mitogen (PWM)-induced plaque-forming cell (PFC) responses were inhibited by C3-coated zymosan particles and by purified human C3b. C3b inhibited the PWM-driven responses in a dose-dependent fashion, and it was necessary for C3b to be present in the early phases of the cultures. C3b acted directly on B cells rather than on helper T cells because it inhibited the PFC responses of MNC depleted of T cells and subsequently stimulated with a T cell-independent Epstein Barr virus mitogen. Furthermore, C3b failed to stimulate the generation of suppressor lymphocytes and/or monocytes that might have been responsible for the inhibition of B cell responses. Our results indicate that C3b or its fragments exert negative modulatory effects on human B lymphocyte responses.