Interleukin-5 induces maturation but not class switching of surface IgA-positive B cells into IgA-secreting cells.
There is a body of evidence suggesting that IgA production is regulated by helper T cells or their products. To elucidate molecular mechanisms of IgA production, the role of lymphokines in the in vitro antigen-specific and polyclonal IgA responses was examined. Supernatants from antigen-stimulated T cells or mitogen-stimulated T-cell clones can enhance 2,4-dinitro phenyl (DNP)-specific IgM, IgG1 and IgA production in cultures of DNP-ovalbumin (OVA)-stimulated T-cell-depleted spleen cells from DNP-keyhole limpet haemocyanin-primed mice. The IgA enhancement was inhibited by anti-IL-5 monoclonal antibody. Purified recombinant IL-5 could also enhance anti-DNP IgA production in a dose-dependent manner. This enhancing effect was not substituted by IL-1, IL-2, IL-3 or IL-4. Polyclonal IgA secretion of lipopolysaccharide-stimulated normal B cells was augmented preferentially by IL-5, but not by IL-4. Surface IgA-positive (sIgA+) B cells, but not surface IgA-negative B cells, responded to IL-5 for the development of IgA-secreting cells. Limiting-dilution analysis revealed that IL-5 increases the frequency of IgA-secreting cells in sIgA+ B-cell populations. These results indicate that IL-5 plays an essential role in the antigen-specific and polyclonal IgA formation as a maturation-inducing factor rather than class-switching factor.
Matsumoto
R
R
Department of Biology, Institute for Medical Immunology, Honjo, Kumamoto, Japan.
Matsumoto
M
M
Mita
S
S
Hitoshi
Y
Y
Ando
M
M
Araki
S
S
Yamaguchi
N
N
Tominaga
A
A
Takatsu
K
K
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D002454:Cell Differentiation / Q000187:drug effects; D005260:Female; D006825:Hybridomas; D007070:Immunoglobulin A / Q000276:immunology*; D015848:Interleukin-5 / Q000276:immunology / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D013047:Specific Pathogen-Free Organisms; D013601:T-Lymphocytes / Q000276:immunology
D000911:Antibodies, Monoclonal; D007070:Immunoglobulin A; D015848:Interleukin-5