IL-4, but not IL-5, can act synergistically with B cell activating factor (BCAF) to induce proliferation of resting B cells.
B cell activating factor (BCAF) was initially identified in the supernatant of the murine T helper cell clone 52-3 (52-3 SN) because of its ability to promote activation and proliferation of resting B cells in the absence of any other costimulus. In this paper, we show that 52-3 T helper cells also secrete IL-4 and IL-5 and we have analyzed the influence of these two lymphokines on B cell proliferation induced by BCAF-containing 52-3 SN. Using the neutralizing anti-IL-4 monoclonal antibody 11B11, we observed partial inhibition of B cell proliferation. 52-3 SN free of IL-4 prepared using an immunoabsorbent column was still able to induce significant B cell proliferation. Although recombinant IL-4 alone does not induce B cell proliferation, it increased the proliferation induced by IL-4-free 52-3 SN. Kinetic studies showed that IL-4 is required at the start of B cell cultures in order to exert optimal synergistic effects. In contrast, anti-IL-5 monoclonal antibody NC17 did not affect the B cell proliferative activity of 52-3 SN whether or not IL-4 was present. When 52-3 SN was tested on dextran-sulfate-activated B cells, IL-5 and BCAF activities were detected but only the IL-5 activity was neutralized by monoclonal antibody NC17. These results demonstrate that (i) BCAF-containing SN can induce proliferation of resting B cells independently of IL-4 and IL-5, and (ii) IL-4, but not IL-5, can act synergistically with BCAF to induce B cell proliferation.
Jankovic
D L
DL
Unité d'Immunogénétique Cellulaire, Institut Pasteur, Paris, France.
Abehsira-Amar
O
O
Korner
M
M
Roth
C
C
Hitoshi
Y
Y
Takatsu
K
K
Theze
J
J
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000937:Antigen-Antibody Reactions; D001402:B-Lymphocytes / Q000166:cytology* / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004357:Drug Synergism; D015847:Interleukin-4; D015848:Interleukin-5; D007378:Interleukins / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D006377:T-Lymphocytes, Helper-Inducer / Q000502:physiology*
D000911:Antibodies, Monoclonal; D015848:Interleukin-5; D007378:Interleukins; D015847:Interleukin-4