Regional dichotomy of interleukin-4 and -5 regulation of senescent B cell responses specific for cholera toxin in Peyer's patches, lamina propria, and mesenteric lymph nodes.

The capacity of exogenous interleukin-4 (IL-4) and IL-5 to augment the antigen-specific senescent Peyer's patch (PP), lamina propria (LP), and mesenteric lymph nodes (MLN) B cells was investigated in the present studies. CTx-primed lymphocytes in the PP, LP, and MLN were obtained from 4-and 24-month old C57BL/6J male mice, 14 days after oral immunization with cholera toxin (CTx). Cells were cultured optimally for 4 days either alone, with lipopolysaccharide (LPS), with LPS plus recombinant IL-4 or IL-5, or with LPS plus IL-4 or IL-5 plus monoclonal antibodies specific for the respective interleukin. Culture supernantants were tested for IgA and IgG anti-CTx antibodies by an ELISA assay. The data indicated impaired antibody responses of aged PP and MLN B cells by the lack of LPS plus IL-4 induced enhancement of anti-CTx IgG antibody production as compared with the young group. For anti-CTx IgA production, aged LP and MLN B cells did not respond equally as well to LPS plus IL-5 stimulation as the young group. In contrast, aged PP B cells responded equally as well by anti-CTx IgA production to LPS plus IL-5 stimulation as the young group. Both anti-IL-4 and anti-IL-5 Mabs blocked the respective IL-4 and IL-5-induced enhancement of antigen-specific IgG or IgA antibody production. The findings suggest a regional dichotomy of IL-5 induced enhancement of aged IgA-producing B cells specific for CTx in the Peyer's patches, mesenteric lymph nodes, and lamina propria.