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Human Germinal Center CD4(+) CD57(+) T Cells Act Differently On B Cells Than Do Classical T-Helper Cells
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-...
Autores principales: | , , , |
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Formato: | Texto |
Lenguaje: | English |
Publicado: |
Hindawi Publishing Corporation
1995
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2275954/ https://www.ncbi.nlm.nih.gov/pubmed/8770558 http://dx.doi.org/10.1155/1995/76790 |
Sumario: | 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. |
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