REQUIREMENT FOR DIFFERENT PRESENTING CELLS AND FOR DIFFERENT PROCESSING MECHANISMS BY HUMAN CD4 T-HELPER CLONES SPECIFIC FOR MYCOBACTERIUM-TUBERCULOSIS ANTIGENS

Human T helper cells specific for mycobacterial antigens have been ext ensively investigated. Differences have been detected according to ant igen specificity and to fine epitope specificity. rn this work we have analyzed two additional parameters that allo iv discrimination among antigen specific T helper cells: requirement for certain types of anti gen presenting cells (APC) and requirement for protease-sensitive anti gen processing pathways. We used T cell clones from peripheral blood o r from pleural exudates, and specific for different antigenic fraction s of M. tuberculosis. APC were autologous peripheral blood mononuclear cells, adherent monocytes, adherent pleural monocytes, EBV transforme d B lymphocytes and dendritic cells. Seven clones our of twelve were s timulated by all APC irrespective of their specificity, whereas other clones had more selective requirements. When protease inhibitors were used during antigen pulsing of APC, the production of certain epitopes , and thus T cell activation, was impaired with six clones out of sixt een. These results demonstrate that the human T helper repertoire spec ific for mycobacterial antigens is highly diverse also according to AP C populations needed for presentation and to processing mechanisms req uired for production of the relevant T epitopes. (C) American Society for Histocompatibility and Immunogenetics, 1998. Published by Elsevier Science Inc.