Enhancement of immune responses to neem leaf extract (Azadirachta indica) correlates with antineoplastic activity in BALB/c-mice.

An aqueous plant extract from Azadirachta indica and its chromatographic fraction F1 (neem extract) exerted immunomodulating and antimetastatic activities in BALB/ c-mice. Regular subcutaneous administration of neem extract yielded significantly increased spleen weight and significant enhancement of peritoneal macrophage activity in the chemiluminescence assay, and activation marker CD-44 expression. The thymus weight and thymocyte counts did not show significant differences in the control and neem extract-treated groups, however, determination of peripheral blood cells revealed significant up-regulations of leukocyte subsets, the lymphocytes and monocytes. Flow cytometric analaysis of lymphocyte supopulations documented increased counts of CD-4 and CD-8 cells and an inreased activation marker expression on lymphocytes (CD-25) and monocytes (MAC-3) in neem-treated mice compared to the control animals. To evaluate the antimetastatic activity of neem extract, sarcoma L-1 cells and lymphosarcoma RAW cells were intravenously inoculated into BALB/c-mice. In these model systems the number of experimental lung and liver metastases decreased relevantly, however, biometrically non-significantly in neem extract-treated animals, as compared to the control mice which received injections of saline solutions. Neem extract can be regarded as an immunomodulating and antimetastatic substance which holds promise for further experimental and clinical investigation.