IL-5 ENHANCES IN-VITRO AND IN-VIVO ANTIGEN-SPECIFIC IGA PRODUCTION INMHC GENETICALLY-DETERMINED LOW IL-5 RESPONDER MICE

Lymphonode cells from BALB/k mice, but not from BALB/c mice, immunized with picryl chloride (PCl) produce IL-5 when stimulated with the spec ific antigen in vitro and this correlates with picryl-specific IgA lev els in vivo, which are 6 to 10 times higher in BALB/k mice. B lymphocy tes from BALB/k mice cultured with PCl-immune T cells from BALB/k prod uce in vivo anti-PCl-IgA, while B lymphocytes from BALB/c mice, cultur ed with T cells from BALB/c mice, fail to produce appreciable amounts of anti-PCl IgA, unless IL-5 is added to cultures. B lymphocytes from both strains of mice produce similar amounts of total IgA antibodies w hen stimulated in vitro with lipopolysaccharide. lit vivo administrati on of IL-5 to BALB/c mice increases significantly PCl-specific IgA lev els to those observed in BALB/k mice and a dose-response analysis reve als that 500 units of IL-5 was the minimal effective dose, although a small increase in PCl-specific IgA levels was observed with 100 units of IL-5. Total IgA levels were increased in both strains of mice follo wing in vivo injection of IL-5, but no significant difference in the v alues was observed. Our results therefore indicate that IL-5 in vivo e nhances antigen-specific IgA production in MHC-determined low IL-5 res ponder mice and suggest an explanation for IgA deficiency in humans. ( C) 1995 Academic Press, Inc.