AMERICAN CUTANEOUS LEISHMANIASIS - IN-SITU CHARACTERIZATION OF THE CELLULAR IMMUNE-RESPONSE WITH TIME

The cellular nature of the infiltrate in the skin of patients with Ame rican cutaneous leishmaniasis was characterized by immunohistochemistr y. The study population consisted of patients in Ceara, Brazil, an are a where Leishmania braziliensis is endemic. Biopsies were taken from l esions present for 0.5-4 months duration and sections were stained wit h antibodies to T cells, T cell subsets, B cells, and macrophage marke rs to quantitate these cell types. The T cells accounted for 37.0 +/- 7.6% (mean +/- SD) of the infiltrate. The average percentages of CD4- and CD8-positive T cells were similar to each other, 20.4 +/- 9.0% and 19.9 +/- 6.7%, respectively. Interleukin-2 receptor-positive cells an d B cells were infrequent, 3.7 +/- 3.0% and 2.3 +/- 3.1%, respectively . When the relationship between the age of the lesion at biopsy and th e cellular phenotype was examined. it was noted that the percentage of positive cells remained fixed for all cell types except for that of g amma delta cells, which decreased with time. It is likely that gamma d elta T cells are important in the early phase of the immune response t o L. braziliensis and may, in general, be important in the early immun e response of granulomatous diseases.