Study on immunity of Leishmania major new crude antigen as a vaccine against leishmaniasis in out bred (resistant) and Balb/c (sensitive) mice

ABSTRACT The aim of this study was to prepare a new formula of Leishmania major (L. major) crude antigen and evaluate its effect on immune system. For this purpose L. major promastigotes were cultured, harvested, washed, and resuspended in physiologic saline and the suspensions were dispersed in five equal batches. 0.1 ml of various doses of the cocktail antigen were injected intradermaly in three groups of mice [Ninety out bred resistant mice (designated type 1 mice) and 90 Balb/c sensitive mice (designated type 2 mice) of both sexes with age of three months]; group I received antigen and a booster dose of the same antigen, group II received Leishmania antigen containing Bacillus Calmette and Guerrin (BCG), group III inoculated with antigen containing BCG and a booster dose of the same antigen, group IV remained intact, groups V and VI received solely BCG, and BCG solvent, respectively without any antigen. Delayed Type Hypersensitivity (DTH) response and spleen white pulp follicles (SWPF) status were evaluated. No significant differences among groups IV, V and VI were seen in two types of mice regarding PPD skin test, in leishmanin skin tests and spleen white pulp statue. However there was a significant difference among three groups of two mice types received the antigens in a dose dependent manner (P<0.05). The results showed that, the new formulated crude L. major antigen induced reasonable DTH immune responses in both types of mice in a dose dependent manner. It is concluded that the group I that received 100 µg/0.1 ml and 200 µg/0.1 ml antigen had high DTH for SLT and low SWPF increasing ,while low DTH and high SWPF were seen in the groups II and III that received 400 µg/0.1ml and 500 µg/0.1ml antigen (P<0.005)