Further evidence for a human B cell activating factor distinct from IL-4.
Supernatants from activated human T cell clones were previously shown to contain B cell-activating factor (BCAF), an activity which results in polyclonal resting B cell stimulation. In the present study, we investigate the relationship between this activity and human interleukin-4 which was also shown to act on resting B cells. The supernatant of the T cell clone TT9 contains IL-4 but anti-IL-4 antiserum does not affect the response of B cells as measured by thymidine uptake or cell volume increase. Furthermore, IL-4 induces Fc epsilon-receptor (CD23) expression on 30% of unstimulated human B cells, whereas BCAF-containing supernatants from clone P2, that do not contain detectable amounts of IL-4, promote B cell proliferation without inducing CD23 expression. Our results therefore establish that IL-4 and BCAF are distinct activities and suggest that they trigger different activation pathways in human B cells. In addition, culture of B cells with T cell supernatants for 72 hr induces a three- to fourfold increase in the expression of HLA-DR, -DP, and -DQ antigens in 50% of B cells. The addition of inhibiting concentrations of anti-IFN-gamma, LT, or IL-4 antisera to the cultures does not change these results. Finally, 30% of B cells cultured with T cell supernatants leave the G1 phase of the cell cycle and 20% reach mitosis. Taken together, our findings further support the existence of a B cell-activating factor responsible for the activation of resting human B cells.
Diu
A
A
Unité d'Immunogénétique Cellulaire, Institut Pasteur, Paris, France.
Février
M
M
Mollier
P
P
Charron
D
D
Banchereau
J
J
Reinherz
E L
EL
Thèze
J
J
D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism; D001402:B-Lymphocytes / Q000502:physiology*; D002453:Cell Cycle; D002478:Cells, Cultured; D002999:Clone Cells; D006681:HLA-D Antigens / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000502:physiology; D015847:Interleukin-4 / Q000502:physiology*; D008213:Lymphocyte Activation; D011961:Receptors, Fc / Q000378:metabolism; D017455:Receptors, IgE
D000944:Antigens, Differentiation, B-Lymphocyte; D006681:HLA-D Antigens; D011961:Receptors, Fc; D017455:Receptors, IgE; D015847:Interleukin-4; D007371:Interferon-gamma