Comparison of immunogenical potency of Leishmania major (MRHO/IR/ 75/ER) antigens prepared by 3 different methods in conjunction with Alum-Naltrexone adjuvant in BALB/c mice

Abstract

Objectives: To evaluate the immunization ability of three Leishmania major antigens including formaline killed promastigotes (FKP), autoclaved Leishmania major (ALM) and soluble Leishmania antigen (SLA), they were used to immunize BALB/c mice in association with a mixture of alum and naltrexone (Alum-Nalt) as adjuvant.

Methods: Each mouse from any of three groups received FKP, ALM or SLA antigens. Three additional groups were injected with same antigenes plus Alum-Nalt. One more group was injected with PBS to be the control group. Booster injections were given at 14th and 28th days. Two weeks after the last immunization, seven mice from each group were exposed to live promastigotes subcutaneously, and skin lesion formation among each mouse was monitored and recorded for 60 days. One week later, cellular and humoral immune responses of other immunized mice were evaluated by measuring the serum levels of anti-ALM-specific IgG1, IgG2a and total IgG antibodies, splenic anti-ALM-specific IFN-γ and IL-5 production and splenic lymphocyte proliferation after adding ALM.

Results: In the challenge test, all mice immunized with ALM antigen and Alum-Nalt were prevented from formation of skin ulcer. Also, the mice from the same group showed higher IFN-γ production and splenic lymphocyte proliferation and higher anti-ALM-specific IgG2a production.

Keywords: Leishmania major, Immunization, Alum, Naltrexone, Opioid-receptor