The effects of interleukins 5 and 6 on immunoglobulin production in rat lacrimal glands.

This study investigated the effects of recombinant murine IL-5 (rmIL-5) and recombinant human IL-6 (rhIL-6) on immunoglobulin production by cultured rat lacrimal gland tissue, and compared the responses to those of cells of nonmucosal origin. Both rmIL-5 and rhIL-6 enhanced IgA, IgG, and IgM production by resting unfractionated rat spleen cells. Detectable levels of all three immunoglobulin isotypes were observed in the culture supernatants of unstimulated rat lacrimal gland tissue after 7 days in culture. Incubation of lacrimal gland tissue with rmIL-5 (50 U/ml) enhanced the levels of IgA, but had no effect on the levels of IgG or IgM. Incubation with rhIL-6 (50 U/ml) enhanced IgA production, but inhibited the secretion of both IgG and IgM. A combination of both IL-5 and IL-6 enhanced IgA levels above those which were observed for each individual lymphokine and inhibited the production of IgG and IgM to a greater degree than did IL-6 alone. These data support a potential regulatory function for lymphokines in glandular mucosal tissue and suggest the presence of a distinct regulatory mechanism in one glandular mucosal tissue which has not been noted using isolated cells derived from either Peyer's patch or spleen.