IL-4 and IL-2 upregulate the expression of antigen B7, the B cell counterstructure to T cell CD28: an amplification mechanism for T-B cell interactions.
We recently generated mAb 104 which is specific for the B cell activation antigen Ag B7. With this we studied the regulation of Ag B7 expression on normal tonsillar B lymphocytes as well as the activities of B7+ and B7- activated B cells. SAC and to a lesser extent anti-IgM antibody upregulated Ag B7 and this was further enhanced by IL-2 and most notably IL-4. Ag B7 was expressed on virtually all sIgG+ and sIgA+ B cells and approximately half of the sIgD+ and sIgM+ B cells. SAC-stimulated B7+ B cells proliferated and produced IgM, IgG and IgA in response to IL-2 and IgM and IgG in response to IL-4. SAC-stimulated B7- B cells proliferated and produced only IgM in response to IL-2 and IL-4. Considering that Ag B7 has recently been shown to be the counterstructure of the T cell CD28 and that CD28 triggering strongly enhances cytokine production by T cells, it is likely that the CD28/B7 interaction represents an important amplification phenomenon in T-B cell interaction leading to humoral immune responses. The preferential expression of Ag B7 on IgG and IgA committed cells suggests that CD28/B7 interaction may be more specific to secondary antibody responses provided by memory T and B cells.
Vallé
A
A
Schering-Plough, Laboratory for Immunological Research, Dardilly, France.
Aubry
J P
JP
Durand
I
I
Banchereau
J
J
D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis* / Q000502:physiology; D000954:Antigens, Surface / Q000032:analysis*; D001402:B-Lymphocytes / Q000276:immunology*; D018106:CD28 Antigens; D002450:Cell Communication; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007376:Interleukin-2 / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000276:immunology*; D015854:Up-Regulation
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D018106:CD28 Antigens; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007376:Interleukin-2; D015847:Interleukin-4