Evaluation of the stability and immunogenicity of autoclaved and nonautoclaved preparations of a vaccine against American tegumentary leishmaniasis

摘要

The immunogenicity of autoclaved and nonautoclaved preparations of a vaccine composed of whole antigens from killed promastigotes of Leishmania amazonensis was evaluated. Leishmanin skin-test (LST)-negative volunteers were immunized with either autoclaved or nonautoclaved vaccine preparations (32 and 36 subjects, respectively) that had been maintained at 4deg C for 1 year prior to the trial. Immunological tests were performed 2 days before and 40 days after vaccination. The LST conversion rates induced by the autoclaved and nonautoclaved vaccines were significantly different: 59 and 83%, respectively. Leishmania antigen-stimulated proliferative responses of peripheral blood mononuclear cells (PBMC) were significantly higher after vaccination than before vaccination in both groups. The CD8- subset was predominant over the CD4+ subset among the Leishmania-reactive cells after vaccination in both groups. The production of interferon-gamma by the Leishmania antigen-stimulated PBMC was significantly higher after vaccination than before in the group receiving the nonautoclaved vaccine but not in the autoclaved vaccine group. Interleukin (IL)-2 was found both before and after vaccination with no differences between its levels in either group. IL-4 was notdetected in either group.