Postnatal development of lymphocyte subpopulations in the intestinal mucosa in goat

The incidence and location of CD2+, CD4+, CD8+ and γδ T-lymphocytes and B-lymphocytes were studied in the intestinal mucosa in goats of one week, one month, three months and seven months old, using monoclonal antibodies and immunohistochemical methods. At all ages CD2+ lymphocytes were the major subpopulation in the intestinal mucosa, more numerous in the small than in the large intestine and in the villi than in the crypt region. In one week-old animals most of CD2+ lymphocytes were scattered in the lamina propria and the number of lymphocytes that expressed CD4 was less than those that expressed CD8, resulting in a CD4CD8 ratio less than 1. CD2+ lymphocytes increased markedly until one month old, with a higher increase of CD4+ subpopulation than CD8+ with an inversion of the CD4CD8 ratio. CD4+ lymphocytes were localised in the lamina propria forming clusters, whereas CD8+ lymphocytes were scattered peripherally under the epithelium and in older animals from three month old, CD8+ lymphocytes were also abundant between epithelial cells. The γδ T-lymphocytes recognised with the mAb CACTB6A represented a minor subpopulation located between epithelial cells or in the lamina propria, no evident changes were observed with age. IgM+ cells were a minor subpopulation in all animals (never higher than 1 cell per 1500 μm−2) located in the crypt region of the lamina propria.