Immunization of hamsters with TLCK-killed parasites induces protection against Leishmania infection.

Hamsters immunized with N-p-tosyl-L-lysine-chloromethyl ketone TLCK-treated L. brasiliensis brasiliensis (LB) from culture, infected with LB amastigotes presented: a gradual increase in T and B cell responsiveness to mitogens by lymph node lymphocytes, and an increased response to concanavalin A with no changes for dextran sulphate and pokeweed mitogen in splenocytes. Absence of parasites in lymph nodes after 6 weeks post-infection and a nodule 4 times smaller than that of infected control animals. The nodule was undetectable after 70 days of infection. Hamsters preimmunized with TLCK-treated L. donovani (LD) from culture did not show suppression of the blastogenic response to mitogens of spleen and lymph node cells after infection with LD amastigotes and survived for more than one year, whereas infected, unimmunized animals died five months after infection. Animals preimmunized with culture parasites (LB or LD) treated with phenyl-methyl-sulphonyl-fluoride (PMSF) and infected with LB or LD amastigotes did not show any protective effect.