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Developmental Immunology
Volume 4 (1995), Issue 3, Pages 189-197

Human Germinal Center CD4+ CD57+ T Cells Act Differently On B Cells Than Do Classical T-Helper Cells

1Institute of Human Histology, University of Liege, rue de Pitteurs, 20, Liege B-4020, Belgium
2Institute of Human Histology rue de Pitteurs, Liege 20 B-4020, Belgium

Received 27 September 1994; Accepted 23 December 1994

Copyright © 1995 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We have isolated two subtypes of helper T cells from human tonsils: CD4+ CD57+ cells, mostly located in the germinal center (GC), and CD4+ CD57- cells, distributed through the interfollicular areas but also present in the GC. In a functional study, we have compared the capacities of these T-cell subtypes to stimulate B cells in cocultures. In order to block T-cell proliferation while maintaining their activation level, we pretreated isolated T cells with mitomycin C prior to culture in the presence of B cells and added polyclonal activators such as PHA and Con A, combined or not with IL-2. Contrary to CD4+ CD57- cells, CD4+ CD57+ cells did not markedly enhance B-cell proliferation. Even when sIgD-B cells typical of germinal center cells were tested, the CD4 CD57 cells had no significant effect. This is in accordance with the location of these cells: They mainly occupy the light zones of the GC where few B cells divide. Even when added to preactivated, actively proliferating cells, CD4+ CD57+ cells failed to modulate B-cell multiplication. On the supernatants of B-cell-T-cell cocultures, we examined by the ELISA technique the effect of T cells on Ig synthesis. Contrary to CD57- T cells, whose effect was strong, CD57+ T cells weakly stimulated Ig synthesis. More IgM than IgG was generally found. Because CD57 antigen is a typical marker of natural killer cells, we tested the cytolytic activity of tonsillar CD4+ CD57+ cells on K562 target cells. Unlike NK cells, neither CD4+CD57+ nor CD4+ CD57- cells exhibit any cytotoxicity. Thus, germinal center CD4+ CD57+ cells are not cytolytic and do not strongly stimulate either B-cell proliferation or Ig secretion. CD4+ CD57- cells, however, enhance B-cell proliferation and differentiation, thus acting like the classical helper cells of the T-dependent areas.