SELECTIVE EXPANSION OF ACTIVATED V-DELTA-4(-INFECTION OF MICE WITH LEISHMANIA-MAJOR() CELLS DURING EXPERIMENTAL)

Previous work from this laboratory has revealed that infection of mice with Leishmanin major leads to an expansion of gamma delta(+) T cells in the spleen. Further examination of the gamma delta(+) T cells expa nding in infected mice has shown that the majority of these cells in t he spleen: lymph nodes, blood and liver expressed the V delta 4 gene s egment. Cell cycle analysis, using propidium iodide incorporation. dem onstrated that while only 1% of alpha beta(+) T cells in the spleen we re in either S + G2/M phase, up to 10% of the gamma delta(+) T cells w ere in cycling phase 8 weeks after infection. Comparison of the state of activation of the two populations in different organs after infecti on, confirmed that gamma delta(+) T cells are actively dividing in lym ph nodes, liver and blood, but not in the thymus or among intraepithel ial lymphocytes. Examination of the expression of different activation markers on the surface of gamma delta(+) T cells in the spleen of bot h normal and chronically infected BALB/c mice by FACS analysis, reveal ed increased expression of LFA-1, CD25, CD44, 4F2, CD28 and the heat-s table antigen,whereas Thy-1 and CD5 decreased. Collectively, these res ults suggest an oligoclonal expansion and activation of gamma delta(+) T cells in response to L. major infection.