Local antibody response in Peyer's patches to the orally administered dietary protein antigen

To understand local antibody production to dietary protein antigens in the gut, the reactivity of the monoclonal antibodies (mAbs) from Peyer's patche s of BALB/c mice raised against orally administered hen egg lysozyme (HEL) was studied. These mAbs were of IgG1 (7 clones), IgA (5 clones) and IgM (13 clones) isotypes. Some of the HEL-binding mAbs preferentially reacted with reduced, carboxy-methylated HEL, rather than with native HEL. MAbs of the IgA and IgM isotypes had cross-reactivity with other unrelated environmenta l antigens such as E. coli, single-strand DNA, and soluble components of mo use food. In contrast, the IgG1 mAbs did not cross-react with these antigen s. The average of the K-d values for HEL of these mAbs was in the order of 10(-6) M, which is moderately higher than those of mAbs from the preimmune repertoire. These results suggest that, under normal physiological conditio ns, orally administered dietary proteins predominantly induce the local pro duction of polyreactive IgA/IgM antibodies cross-reacting with environmenta l luminal antigens.