Norberto David Bassan

Lymphocytes from Peyer’s Patches and Mesenteric Lymph Nodes Proliferation in a Model of Oral and Systemic Sensitization with Ovalbumin

Background : In previous works we demonstrated that subcutaneous sensitization with Ovalbumin (OVA) induce generation of specific IgE antibodies and modifications of immune cells populations in different mucosal sites in rabbit. The aim of the study was the evaluation of OVA specific lymphoproliferation in mesenteric lymph nodes (MLNs), spleen and Peyer’s patch from OVA orally and subcutaneous sensitized and challenged rabbits. Methods : New Zealand white rabbits were divided into six groups: G1 (n=8): orally sensitized and challenged with OVA; G2 (n=10): subcutaneous sensitized with OVA and oral challenged (OVA); G3 (n=10): subcutaneous sensitized and oral challenged with PBS (phosphate buffer saline). G4-G5 and G6 (n=9 each) controls. Four hours after challenge animals were sacrificed and obtained samples were processed for lymphoproliferation studies: isolated cells from MLNs, spleen and Peyer’s patch from the different groups were suspended in culture media containing OVA or Concanavaline A and were cultured for 48, 72 and 120 hours. Proliferation was measured as incorporation of radioactive element as counts per minute (CPM). Results : Spleen derived lymphocytes showed important proliferation at subcutaneous sensitized groups when incubated with OVA. Meanwhile, proliferation was significantly higher in lymphocytes originated in MLNs from subcutaneous OVA sensitized and oral challenged rabbits at 48, 72 and 120 hours of incubation. No significant proliferation was observed in Peyer’s Patch derived lymphocytes. Conclusions : We conclude that proliferation of OVA-specific spleen originated lymphocytes was successful after systemic sensitization but after oral challenge with the antigen, only OVA incubated MLNs-originated lymphocytes showed proliferation as compared with Peyer’s patch. This fact evidence a main participation of MLNs in this model of food allergy.

358 Histochemical Study of Allergic Inflammation in Conjunctiva From Ovalbumin Sensitized Rabbits after Ocular or Nasal Challenge.

Background We previously demonstrated that subcutaneous sensitization with ovalbumin (OVA) induce generation of specific IgE antibodies and quantitative modifications in immune cells populations from different mucosal sites in rabbit. The aim of the study is characterization of eosinophil infiltration in conjunctival mucosa from OVA sensitized and ocular and nasal challenged rabbits. Methods Animals were divided into 4 groups: G1 (n = 9): normal control; G2 (n = 10): subcutaneous sensitized with OVA; G3 (n = 10): subcutaneous sensitized and conjunctival challenged with OVA; G4 (n = 9): subcutaneous sensitized and nasal challenged with OVA. Four hours after challenge animals were sacrificed and obtained samples were processed for histochemistry with cromotrope 2R for eosinophil detection. Cells were counted in 200 high power fields per group. Results Data were expressed as positive cells per high power field. Conjunctival mucosa: G1: 2.3; G2: 3.4; G3: 12.2; G4: 3.3 (G3 vs G1, G2 y G4 P < 0.001). Specific anti-OVA-IgE levels were evaluated by positive passive cutaneous anaphylaxis test (PCA) at 160 fold dilutions. Conclusions We observed an increase in the number of eosinophils-positive cells after local challenge in conjunctiva as compared to normal controls and sensitized and nasal challenged animals. We conclude that systemic sensitization with soluble antigen and conjunctival challenge induces modifications in number of eosinophil populations in conjunctiva but not in nasal challenged rabbits.

Inoculation with Mycobacterium plhei inhibits allergic inflammation in a rabbit model of ovalbumin (ova) sensitization---La inoculación con Mycobacterium phlei inhibe la inflamación alérgica en un modelo de conejos sensibilizados con ovoalbúmina (OVA)

Resumen es: La prevalencia de enfermedades atopicas y otros desordenes autoinmunes tipo Th2 se ha incrementado en los paises occidentales. Una teoria lo explica medi...