[Experimental study on the intestinal mucosal secretary IgA responses to the ovalbumin-induced allergy in mice].

OBJECTIVE

To valuate the intestinal mucosal secretary IgA (sIgA) responses to the ovalbumin-induced allergy in mice, to provide some clues for the exploration of mechanisms and therapeutic methods in the children's food allergy.

METHODS

Female BALB/c mice aged 6 weeks fed on the ovalbulmin-free diet, were randomly divided into 2 groups with 8 mice in each. The mice in group Ch were sensitized with ovalbumin (OVA) intraperitoneal injection two times and challenged intragastrically 3 times. Two days after the last challenge with oral OVA, the mice were sacrificed and the samples were collected. The mice in group Ns were given intraperitoneal and intragastrical normal saline as control. The levels of total IgA and OVA-specific IgA in the intestinal mucus of the mice were determined by ELISA; the immunohistochemical methods were adopted to observe IgA(+) plasmacytes in lamina propria (LP) and surface membrane IgA (smIgA)(+) lymphocytes in peyer's patch (PP); the IL-4 mRNA expression in LP was assessed by RT-PCR. The IL-4 mRNA expression in PP was evaluated by in situ hybridization.

RESULTS

After the mice in Ch group were sensitized and challenged with OVA, the levels of the total IgA and the OVA-specific IgA in mucus remarkably increased (P < 0.01 respectively), the amounts of the IgA(+) plasmacytes in LP and the smIgA(+) lymphocytes in PP significantly increased (P < 0.01 respectively); a significantly positive correlation was found among the total IgA levels, the OVA-specific IgA levels, the IgA(+) plasmacyte counts in LP and the smIgA(+) lymphocyte counts in PP (P < 0.01 respectively); the mRNA expressions of IL-4 in LP and in PP were significantly augmented (P < 0.01 respectively); significantly positive correlations were found either between the IL-4 mRNA expression and the IgA(+) plasmacyte counts in LP (P < 0.01) or between the IL-4 mRNA expression and the smIgA(+) lymphocyte counts in PP (P < 0.01).

CONCLUSIONS

The intestinal mucosal sIgA responses are abnormally augmented in the ovalbumine-induced allergic mice, which may be partly due to the increased expression of IL-4 mRNA in gut.