Compartmentalisation between Gut and Lung Mucosae in a Model of Secondary Immunodeficiency: Effect of Thymomodulin

Abstract

Compartmentalisation of mucosal immune response seems to be the result mainly of the preferential migration of activated cells back to their inductive sites. The aim of this report was to demonstrate, in a model of secondary immunodeficiency in Wistar rats (severely protein deprived at weaning and refed with casein 20 %; group R21), that the oral administration of Thymomodulin (group: R21TmB) has different effects on gut and BALT (Bronchus-associated lymphoid tissue). Tissue sections (5μ) were studied by immunohistochemistry 1). The oral administration of Thymomodulin restores only in gut Lamina propria (LP) the IgA B and CD4 T cell populations to control levels. The CD8a and CD25 subpopulations do not vary in gut as they return to control levels when refed with 20% casein diet. All the populations mentioned above remained decreased even after receiving Thymomodulin by the oral route. However, the same behaviour was observed for the TCRδ T cells that were decreased and return to normal levels in both mucosae by the effect of the immunomodulator; 2) when studying the iIEL (intestinal intraepithelial lymphocytes) CD8α, CD25 and TCRγδ T cells, that were increased in R21, return to control levels in R21TmB. In BALT intraepithelium CD8α and CD25 T cells remained decreased, while only TCRγδ T cells (increased in R21) return to control values. Conclusions: 1) there exists a compartmentalisation between both mucosae, as T CD4+ and IgA B+ cells are restored by TmB only in gut; 2) only those iIEL involved in inflammation (CD8α+/CD25+ and TCRγδ+/CD25+) are normalised by means of the Thymomodulin 3) however, in BALT, only TCRγδ+ T cells are restored 4) the oral administration of the present immunomodulator may be useful as a therapeutic agent, although the preferential survival in the tissue of initial stimulation is the major factor in the preferential distribution of activated cells.