Neem leaf preparation enhances Th1 type immune response and anti-tumor immunity against breast tumor associated antigen.

An 85-kDa breast tumor associated antigen (BTAA) has been identified and partially characterized from human breast tumors. As BTAA is poorly immunogenic, enhancement of the anti-tumor immunity induced by BTAA is required to obtain an objective clinical response. The potent immune activation by an aqueous preparation of neem (Azadirachta indica) leaf (NLP) suggests its possible utility for enhancing immune responses to tumor vaccines. Mice (Swiss and Balb/c) and rats (Sprague Dawley) immunized with BTAA and NLP have a higher IgG antibody response and a lower IgM response than mice immunized with BTAA alone. Antibody generated by immunization with BTAA and NLP can induce antibody-dependent cellular cytotoxicity (ADCC) and cytotoxic T cell (CTL) response towards BTAA-expressing MCF-7 cells. Antibody produced by vaccination with BTAA alone generated little cytotoxic response. The occurrence of ADCC and CTL response induced by BTAA plus NLP vaccination was possibly assisted by the induction of a Th1 response, as evidenced by the enhanced secretion of IFN-gamma and decreased release of IL-10 from spleen cells and the greater production of IgG2a antibody in immunized mice. As NLP is nontoxic, abundantly available in the Indian subcontinent and can be extracted by a cost-effective method, this preparation may be considered a promising immune enhancer for BTAA vaccine.