Exogenous IL-6 promotes enhanced intestinal antibody responses in vivo

It is well documented that IL-6 plays a critical role in B cell terminal di fferentiation, and in mucosal sites it stimulates proliferation and large-s cale secretion of immunoglobulin by B cells, especially those committed to IgA production. The close juxtaposition of IL-6 mRNA(+) cells to plasma cel ls in the intestinal lamina propria supports the proposition that IL-6 prod uction in situ is an important factor determining the outcome of antibody r esponses at that site. However, it has not been established previously whet her exogenous IL-6 could boost antibody responses in the intestine if admin istered with a challenge antigen. Using a resected gut loop (Thirty-Vella l oop) model, we have been able to demonstrate that in mice with double loops , antibody containing cell responses to lumenal administration of ovalbumin were 50% greater in loops given intralumenal recombinant IL-6 with the cha llenge antigen, than in loops challenged with antigen alone. This demonstra tes the efficacy of IL-6 in promoting accumulation of antibody secreting ce lls in the gut, and suggests a potential therapeutic role for IL-6 to enhan ce responses to mucosal vaccines.