GAMMA-DELTA-T-LYMPHOCYTES IN ORIENTAL CUTANEOUS LEISHMANIASIS - OCCURRENCE AND VARIABLE DELTA-GENE EXPRESSION

It has been suggested that T lymphocytes expressing gammadelta T-cell receptors could play an important role in defence against some intracellular infectious pathogens. The present study was undertaken to characterize the occurrence and variable delta gene expression of T lymphocytes expressing the gammadelta T-cell receptor in oriental cutaneous leishmaniasis. Eleven cases of oriental cutaneous leishmaniasis were investigated by immunohistological analysis using an alkaline phosphatase-anti-alkaline phosphatase (APAAP) technique. In three cases, we observed an increased percentage of gammadelta T cells (about 20% of CD3+ cells). In these cases gammadelta T cells generally expressed the Vdelta2 segment, and only rarely the Vdelta1 gene product. Vdelta2+ cells were predominantly localized in the dermis, and were virtually absent in the epidermal compartment. The rare gammadelta T cells observed in the epidermis were almost exclusively Vdelta1+. This study demonstrates that an increase of gammadelta T cells may be found in oriental cutaneous leishmaniasis, although it is not a constant feature of the disease. The finding of a preferential expansion of the Vdelta2 subset suggests that this subpopulation of gammadelta T cells might be selectively involved in the recognition of Leishmania antigens. The distinct compartmentalization of gammadelta T-cell subpopulations indicates that these subsets may recognize distinct sets of antigens.