The ability of B cells to participate in allogeneic cognate T-B cell interactions in vitro depends on the presence of CD4+ T cells during their development.
We have assessed in vitro whether the absence of T cells in the natural environment of F1 hybrid mice influences the ability of their B cells to participate in an allogeneic interaction with CD4+ cells from parental mice. For this purpose, B cells from athymic CB6F1 nu/nu mice or from CB6F1 mice depleted in different T cell subsets were incubated in vitro with purified CD4+ BALB/c cells. Here, we show that B cells from CB6F1 nu/nu mice or from euthymic CB6F1 mice depleted from birth of CD4+ cells were unable to respond to allogeneic stimulation with BALB/c CD4+ T cells, which produce normal levels of cytokines. The addition of dendritic cells from euthymic CB6F1 mice did not revert this defect. B cells from CB6F1 mice lacking CD4+ T cells showed a selective reduction in the expression of CD23. We found a complete restoration of both the CD23 expression and the ability of CB6F1 nu/nu B cells to respond in vitro to an allogeneic stimulation by CD4+ cells in two instances: (1) after neonatal engraftment of a syngeneic thymus into CB6F1 nu/nu mice, which partially reconstitutes the mature T cell populations; and (2) after preincubation of B cells from CB6F1 nu/nu mice with high concentrations of rIL-4. However, the addition of an anti-CD23 mAb did not interfere with the polyclonal activation of CB6F1 B cells in this system. These results indicate that CD4+ cells play an important role in the functional maturation of B cells by promoting their ability to participate in allogeneic cognate T-B cell interactions.
González
M
M
Immunology Service, Marqués de Valdecilla University Hospital, Santander, Spain.
Merino
R
R
González
A L
AL
Merino
J
J
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D008211:Lymphocyte Cooperation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D017455:Receptors, IgE / Q000276:immunology; D013047:Specific Pathogen-Free Organisms; D013950:Thymus Gland / Q000254:growth & development / Q000276:immunology
D000911:Antibodies, Monoclonal; D016207:Cytokines; D007074:Immunoglobulin G; D017455:Receptors, IgE