AUGMENTATION OF MURINE NATURAL-KILLER-CELL AND ANTIBODY-DEPENDENT CELLULAR CYTOTOXICITY ACTIVITIES BY PHYLLANTHUS-EMBLICA, A NEW IMMUNOMODULATOR

When administered orally, Phyllanthus emblica, an excellent source of vitamin C (ascorbate), has been found to enhance natural killer (NK) c ell activity and antibody dependent cellular cytotoxicity (ADCC) in sy ngeneic BALB/c mice, bearing Dalton's lymphoma ascites (DLA) tumor. P. emblica elicited a 2-fold increase in splenic NK cell activity on day 3 post tumor inoculation. Enhanced activity was highly significant on days 3, 5, 7 and 9 after tumor inoculation with respect to the untrea ted tumor bearing control. A significant enhancement in ADCC was docum ented on days 3, 7, 9, 11 and 13 in drug treated mice as compared to t he control. An increase in life span (ILS) of 35% was recorded in tumo r bearing mice treated with P. emblica. This increased survival was co mpletely abrogated when NK cell and killer (K) cell activities were de pleted either by cyclophosphamide or anti-asialo-GM, antibody treatmen t. These results indicate: (a) an absolute requirement for a functiona l NK cell or K cell population in order that P. emblica can exert its effect on tumor bearing animals, and (b) the antitumor activity of P. emblica is mediated primarily through the ability of the drug to augme nt natural cell mediated cytotoxicity.