Visceral leishmaniasis is associated with an antigen-specific immunosuppression during the acute disease. Patients become responsive to Leishmania antigen in both in vivo and in vitro assays after successful antimony therapy. The cell type involved in the suppression of lymphocyte reactivity to Leishmania antigen was studied by selective depletion of mononuclear cell (MNC) populations and in co-cultivation experiments. Adherent cells were depleted on plastic and by passage on nylon wool columns. High-avidity Fc+ cells were depleted by adherence to BSA-anti-BSA complexes and OKT4+ and OKT8+ cells were depleted by treatment with monoclonal antibody (anti-OKT4+ and OKT8+) and complement. Depletion of MNC preparations of adherent cells, high-avidity Fc+ cells, OKT4+ cells and OKT8+ cells failed to restore the lymphocyte reactivity to Leishmania antigen. Antimony therapy was associated with restoration of the proliferative responses of unseparated MNC (before treatment 460 +/- 76 cpm and after treatment 4,293 +/- 1,442 cpm). Co-culture of frozen cells obtained before chemotherapy with autologous MNC obtained after treatment reduced the response of posttreatment cells to Leishmania antigen by 80%. We conclude that the antigenic specific suppression of lymphocyte proliferation in visceral leishmaniasis is cell mediated.
E M Carvalho, O Bacellar, A Barral, R Badaro, W D Johnson Jr
Guidelines: The Editorial Board will only consider letters that we deem relevant and of interest to our readers. We will not post data that have not been subjected to peer review, nor will we post letters that are essentially a reiteration of another letter. We reserve the right to edit any letter for length, content, and clarity. Authors will be notified by e-mail if their letters were accepted. No appeals will be considered.
Specific requirements: All letters must be 400 words or fewer. You may enter the letter as plain text or HTML. The author's name and e-mail address are required, and will be posted with the letter. All possible conflicts of interest must be noted, even if they are not posted. If you wish to include a figure (keep in mind that non-peer-reviewed data will not be posted), please contact the editors directly at firstname.lastname@example.org.