Nasopharinx-associated lymphoid tissue in a model of secondary immunodeficiency in rats.

SOSA G; QUIROGA MF; ROUX M

Córdoba, Argentina

Congreso; VII Congreso Latinoamericano de Inmunología; 2005

ALAI

Our previous studies in a model of secondary immunodeficiency (R21) in rat NALT have shown a decrease of CD5+ T cells, but not IgA+ B cells.  The aim of the present report was to analyze: 1) by flow cytometry, T-cell populations and co-expressions in NALT; 2) by ELISA, IgA levels in nasal fluids from R21 rats compared to controls (C60) and to know the response of R21 rats to intranasal OVA and OVA-IL12.  Weanling Wistar rats were fed a protein-free diet followed by administration of a 20% caseid diet for 21 days (R21).  Cell suspensions were labelled for cytometric analysis and IgA measured on nasal fluids from C60, R21, and R21-OVA or OVA/IL-12.  Results: X±SE, nn=5, Student’s t Test: 1) T cells (% C60 vs R21) CD4 : 37.9±12.2 vs 66.0±9.2, NS ; CD8a : 6.8±0.5 vs 3.3±1.3, p=0.0301 ; TCab : 50.3±14.5 sv 27.1±1.1 p=0.040; TCRgd: 0.95±0.22 vs 0.92±0.16, NS; CD8a-TCRgd: 0.72±0.52 vs 0.79±0.54, NS; CD4-TCRab: 37.2±10.4 vs 25.3±10.4, NS.  2) IgA levels (ng/ml): C60 vs R21: 7870±1262 vs 7208±1286, NS ; R21 OVA vs R21 OVA/IL-12: 6105±124 vs 13955±1641, p=0.002.  Conclusions: 1) CD4 and TCRab predominate in C60; 2) in R21 only CD8a and TCR ab are diminished; 3) IgA leves are similar in C60 and R21; 4) when R21 rats were immunized with OVA-IL12, the response increased significantly.  These findings show: 1) a unique behaviour of NALT within the mucosal immune system; 2) the increased response to OVA/IL-12 acts as an adjuvant for the IgA response to OVA.