Postnatal development of lymphocyte subpopulations in the intestinal lymph nodes in goats.

The incidence and location of CD2+, CD4+, CD8+ and gamma/delta T lymphocytes and IgM+ B lymphocytes were studied in the intestinal lymph nodes in 1-week, 1-month, 3-month and 7-month-old goats, using monoclonal antibodies and immunohistochemical methods. The cortical area of the intestinal lymph nodes in 1-week-old animals contains only primary follicles occupied by IgM+ B lymphocytes and some CD2+ CD4+ T lymphocytes. In goats older than 1 month, secondary follicles, that increased in number and size with age, were observed; the light zone of the germinal centre was occupied by IgM+ lymphocytes and some CD2+ and CD4+ T lymphocytes. In the other compartments of the lymph nodes, B lymphocytes were scarce, their number increasing with age in the medulla and diminishing in the paracortex. The numerous CD2+ T lymphocytes in the interfollicular area increased in number in the paracortical area of the 7-month-old goats, simultaneously with an increase in the MHC II+ dendritic cells and the CD4/CD8 ratio, which was greater than 1. The gamma/delta T lymphocytes represented a minor subpopulation scattered through the lymph nodes.