IgG1 and IgG2a Profile of Serum Antibodies to Leishmania major Amastigote in BALB/c and C57BL/6Mice

It is well accepted that in experimental model of Leishmania major infection, BALB/c mice mount a Th2 response and produce IgG1 predominantly whereas C57BL/6mice enhance Th1 response with the biased production of IgG2a antibodies. Therefore, screening for parasite antigens on the basis of reactivity with sera from infected susceptible or resistant mice might be used for the identification of Th1- or Th2-inducing antigens. In this study, the antigenic profile of Leishmania majoramastigote that induce IgG1 or IgG2a isotypes in infected BALB/c or C57BL/6 mice were compared. Western blot analyses revealed that 27, 40, 43, 45 and 114 kDa proteins elicited IgG1 and not IgG2a in both BALB/c and C57BL/6 mice and 55 kDa protein was recognized exclusively by IgG1 of BALB/c mice sera. On the contrary, the bands corresponding to proteins with molecular weights (MW) of 30, 35, 52, 58 and 66 were intensively immunostained with IgG2a from C57BL/6 mice which made them potential candidates for eliciting Th1 response. In conclusion, the results showed that the generation of the immune responses depended on the mouse strain and some leishmanial antigens had an intrinsic potency to elicit Th2 responses.