FIG. 6.

Lactobacillus-specific IgG2a and IgG1 isotypes in the serum of monoassociated mice. After 30 days of colonization, serum was collected from L. johnsonii-associated mice and assayed for L. johnsonii-specific IgG2a (A) and IgG1 (B). Serum from L. paracasei-colonized mice was assayed for L. paracasei-specific IgG2a (C) and IgG1 (D). Results were extrapolated from a positive serum standard from mice immunized systemically with L. johnsonii or L. paracasei crude antigens and represent means for eight mice per group (± standard error of the mean). The data show results from one representative experiment out of three. *, significantly increased above values for germfree controls (P < 0.05).