Immunopathological modifications in the rectal mucosa from an animal model of food allergy.

Aim: The aim is to determine immunopathological modifications in rectal mucosa from rabbit after local challenge in sensitized animals with ovalbumin (OVA).

Experimental Design: Thirty rabbits divided into three groups: G1: normal, G2: subcutaneously OVA sensitized, G3: sensitized, locally OVA challenged and sampled 4 hours after challenge. Specific anti-OVA IgE levels were evaluated by passive cutaneous anaphylaxis test (PCA). In each group 200 high microscopical power fields (HPF) were counted. Results were expressed as arithmetic mean and SE. Statistical analysis was made using Student t test. Anti-CD4, CD5, micro chain, CD25 and RLA II monoclonal antibodies were used. Avidin biotin horseradish peroxidase system was used.

Results: CD 4: G1: 8.3 +/- 0.06; G2: 13.4 +/- 0.08 and G3: 8.25 +/- 0.06. CD 5: G1: 7.3 +/- 0.05; G2: 9.4 +/- 0.05 and G3: 11.3 +/- 0.06. CD 25: G1: 13 +/- 0.08; G2: 15.1 +/- 0.13 and G3: 25.5 +/- 0.15. mu chain: G1: 10.4 +/- 0.06; G2: 3.8 +/- 0.02 and G3: 6.0 +/- 0.10. RLA II (DR): G1: 11.6 +/- 0.05; G2: 19.2 +/- 0.09 and G3: 19.1 +/- 0.11. In all cases, experimental groups (G2 and G3) presented statistical significant differences vs. control group (G1) (p < 0.001).

Conclusions: Interleukin-2 receptor (CD25+ cells) increase in experimental groups. Cells expressing micro chain decreased in G2 and G3 likely due to activation of B cells and subsequent expression of other immunoglobulin chains in cell surface. RLA II expression is higher in G2 and G3. This receptor is considered an activation marker expressed by macrophages, T and B cells. We conclude that obtained data are important to elucidate immunopathology of local anaphylactic reaction in rectal mucosa from systemic sensitized animals.