Analysis of IgA-producing hybridomas derived from peritoneal B1 cells

Pulmonary α-1,3-Glucan-Specific IgA-Secreting B Cells Suppress the Development of Cockroach Allergy

There is a higher incidence of allergic conditions among children living in industrialized countries than those in developing regions. One explanation for this is reduced neonatal exposure to microbes and the consequent lack of immune stimulation. Sensitivity to cockroach allergen is highly correlated with the development of severe asthma. In this study, we determined that an Ab to microbial α-1,3-glucan binds an Enterobacter species and cockroach allergen. Neonatal, but not adult, mice immunized with this α-1,3-glucan-bearing Enterobacter (MK7) are protected against cockroach allergy. Following exposure to cockroach allergen, α-1,3-glucan-specific IgA-secreting cells are present in the lungs of mice immunized with MK7 as neonates but not in the lungs of those immunized as adults. Mice that are unable to generate anti-α-1,3-glucan IgA Abs were immunized with MK7 as neonates and were no longer protected against cockroach allergy. Thus, neonatal, but not adult, exposure to α-1,3-glucan results in suppressed development of cockroach allergy via pulmonary α-1,3-glucan-specific IgA-secreting cells.

T-Independent IgA Responses to Microbial Polysaccharides

There is accumulating evidence indicating the presence in vivo of T-independent routes of IgA response in addition to the conventional T-dependent IgA response. Factors influencing these alternative pathways of IgA responses may include the structural characteristics of a stimulating antigen, the nature of responding B cells, and the microenvironment. The structural complexity of polysaccharide antigens has made it difficult to summarize a general scheme for the antibody responses they induce. Instead, one may expect that each individual polysaccharide may be able to create a unique microenvironment by activation of specific cell populations in the repertoires of non-T cell types. A specific pattern of B cell response may thus be elicited by TI stimulation. Recognition of such a unique property of a TI antigens is necessary for us to better understand the T-independent IgA response. Information obtained may have an impact on the development of vaccination strategies directed at the mucosal immunity mediated by IgA antibodies.