IgA B lymphocytes and subpopulations of T lymphocytes in the intestinal villi of immunodeficient Wistar rats.

The aim of this study is to characterize intraepithelial lymphocytes (IEL) and lamina propria lymphocytes (LPL), as well as IgA B cells in the intestinal villi of the small intestine of rats which were fed a protein free diet (PF) and of those which were refed a 20% casein diet for 21 days (R21). Age matched control groups are also analyzed. T cell subsets and IgA-B cells were studied in tissue sections by the immunofluorescence technique. Lamina propria (LP) of the small intestine of the PF group were almost devoid of IgA-B cells; in the R21 group, the number of IgA-B cells was significantly diminished, when compared to the control group. The number of LPL in R21 group was not significantly different from the control group. W3/25+ (CD4) IEL diminished significantly in the intestinal villi of R21 group, while OX8+ (CD8) and OX22+ (CD45R) IEL were significantly increased when compared to the control group. These results indicate that: 1) Protein deficiency provokes an impairment of IgA-B cell terminal differentiation. 2) There is repopulation of LP by T cells in the R21 group. 3) The increased number of OX8+ (CD8) and OX22+ (CD45R) IEL might permit induction of intestinal delayed type hypersensitivity, thereby abrogating oral tolerance of systemic delayed type hypersensitivity.