HUMAN ALPHA-BETA AND GAMMA-DELTA T-CELLS FROM UNEXPOSED INDIVIDUALS RESPOND TO PROTEIN ANTIGENS OF THE YEAST FORM OF PARACOCCIDIOIDES-BRASILIENSIS

Paracoccidioides brasiliensis, a dimorphic fungus, causes chronic gran ulomatous mycosis in susceptible individuals. Different reports have s hown that cell-mediated immunity is essential for protection against s ystemic mycosis, including paracoccidioidomycosis. We analyzed the rea ctivity of ap and gamma delta T cells from unexposed Caucasian donors to P. brasiliensis yeast form components. Our results indicate: (i) al pha beta and gamma delta T cells proliferate after in vitro stimulatio n with lysates of P. brasiliensis; (ii) similar numbers of alpha beta T cells (f = 1/21,000) and of gamma delta T cells (f = 1/8000) respond to P. brasiliensis; (iii) P. brasiliensis-reactive gamma delta T cell s express the V gamma 9V delta 2 TCR; (iv) the stimulatory activity of P. brasiliensis for both alpha beta and gamma delta T cells primarily resides in a high molecular weight (100 kDa) and in a low molecular w eight (<1 kDa) fraction; (v) the ligands responsible for stimulation o f both alpha beta and gamma delta T cells are sensitive to proteinase treatment. We conclude that both alpha alpha and gamma delta T cells f rom healthy individuals respond to ubiquitous protein antigens of P. b rasiliensis.