B cell activator. Effects on B cell expression of CD23, proliferation, and antibody secretion.
The studies herein describe a B cell hybridoma-derived, low m.w. (less than 1000 Da), hydrophilic mediator denoted B cell activator (BCA). BCA stimulates B cell expression of IgE-specific FcR (Fc epsilon RII or CD23) in a manner similar to IL-4. However, BCA can be readily distinguished from IL-4 because it does not 1) enhance B cell Ia expression; 2) bind 11B11 anti-IL-4 mAb; or 3) elicit superinduction of Fc epsilon RII expression or IgE production in cultures of LPS-activated B cells. Moreover, BCA is considerably more mitogenic than IL-4 for LPS-activated B cells and, in contrast to IL-4, lacks mitogenicity for anti-mu-activated B cells. BCA can enhance IgG2b and IgG3 production by LPS-activated B cells, responses that are suppressed by IL-4. BCA alone did not stimulate IgE and IgG1 production by LPS-activated B cells, but exerted synergistic activity when combined with IL-4 in stimulating secretion of these antibody isotypes. Finally, secondary Ag-driven IgG1, IgE, and IgA antibody responses can be stimulated by BCA in vitro. Thus, BCA appears to be a novel mediator with broad B cell activation properties.
Marcelletti
J F
JF
Division of Immunology, Medical Biology Institute, La Jolla, CA 92037.
Matsushita
S
S
Katz
D H
DH
D000818:Animals; D000917:Antibody Formation / Q000187:drug effects; D000921:Antibody-Producing Cells / Q000378:metabolism; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D015847:Interleukin-4 / Q000494:pharmacology*; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D008970:Molecular Weight; D011961:Receptors, Fc / Q000378:metabolism*; D017455:Receptors, IgE
D000944:Antigens, Differentiation, B-Lymphocyte; D000949:Histocompatibility Antigens Class II; D008222:Lymphokines; D011961:Receptors, Fc; D017455:Receptors, IgE; D015847:Interleukin-4