Loss of ileal IgA+ plasma cells and of CD4+ lymphocytes in ileal Peyer's patches of vitamin A deficient rats

Abstract

Child mortality in diarrhoeal disease is increased significantly by vitamin A deficiency in poor countries. The pathological mechanisms are not known in detail. However, in this paper we report that vitamin A-deficient Wistar rats had much reduced IgA+ plasma cells in the ileal lamina propria (eightfold reduction from 470 cells/mm(2), P = 0.009), as well as a prominent reduction of CD4+ cells in the parafollicular regions of ileal Peyer's patches (reduction from 7200 to 105 cells/mm(2), P = 0.009). IL-2Ralpha-chain (CD25) positive lymphocytes in the ileal Peyer's patches were also reduced significantly in vitamin A deficiency (from 1400 to 300 cells/mm(2), P = 0.009). The density of CD8 cells tended to be increased relative to the control animals (from 5100 to 6000 cells/mm(2), not statistically significant). In conclusion, the marked decrease of lamina propria IgA+ plasma cells may be one cause of the high diarrhoeal mortality in vitamin A deficiency. This, in turn, appears to be related to reduced numbers of activated or regulatory CD4+ T cells in Peyer's patches.

Fig. 1

Number of IgA⁺ plasma cells per mm² in ileal lamina propria. Each open ring represents one vitamin A-deficient rat (VAD); well-nourished control rats (NORM) are represented by filled squares. Statistical significance was determined by the Mann–Whitney U-test, P-values are indicated within the figure. Horizontal lines represent the median of each group.

Fig. 2

IgA⁺ plasma cells in ileal sections from a vitamin A-deficient rat (top) and a vitamin A-replete rat (bottom).

Fig. 3

(a) Number of CD4⁺ cells per mm² in the T cell parafollicular areas of Peyer's patches. (b) Number of CD25⁺ cells per mm² in T cell areas of Peyer's patches. (c) Frequency of CD25⁺ cells out of total cells in T cell areas of Peyer's patches. (d) Number of CD8⁺ cells per mm² in the T cell areas of Peyer's patches. Statistical significance was determined by the Mann–Whitney U-test, P-values are indicated within the figure. Horizontal lines represent the median of each group.

Fig. 4

CD4⁺ cells in sections of ileal Peyer's patches from a vitamin A-deficient rat (top) and a vitamin A-replete rat (bottom).