Non-specific and specific stimulation of resistance against Leishmania donovani in C57BL/6 mice

Stimulation by intravenous injections of glucan, a (31,3 polyglucose, provided a significant degree of resistance in mice against Leishmania donovani. The response of C57BL/6 animals was dose-dependent. A single glucan injection before or after infection induced significant resistance bu t to a lesser degree than two or th ree injections. Im m unization by injections of formalin-killed promastigotes w ith glucan via the subcutaneous or intravenous routes provided greater resistance than glucan or dead parasites alone against subsequent infection with vi­ able parasites. Subcutaneous immunization with promastigotes from cul­ tures passaged 10 times in vitro and those from cultures m aintained for 25 passages elicited a similar degree of resistance against infection and induced positive skin test responsiveness against leishmanial antigen prior to infection.