Development of Mucosal Humoral Immune Responses in Germ-Free (GF) Mice

Abstract

GF mice can be effectively mono-associated with gram-negative bacteria Morganella morganii. This colonization results in hypertrophy of Peyer’s patches (PP), including germinal center reactions (GCR), and the development of specific IgA responses detected in vitro in PP fragment cultures. IgA antibody against the phosphocholine (PC) determinant characterizes this response. Although the mucosal response to M. morganii develops in 14 days, colonization with another, related gram-negative bacteria-proteus spcs., fails to elicit GCR or IgA antibody responses over a period of weeks. However, oral administration of cholera toxin (CT) during this period results in a prompt mucosal immune response vs. both the CT as well as the commensal bacteria. We are employing a T-B clonal microculture to quantitate and determine the kinetics of development of specific IgA pre-plasmablasts and memory B cells in relation to GCRs.