PICROLIV, THE IRIDOID GLYCOSIDE FRACTION OF PICRORHIZA-KURROA, SELECTIVELY AUGMENTS HUMAN T-CELL RESPONSE TO MYCOBACTERIAL PROTEIN ANTIGENS

Mycobacterial and other intracellular parasitic diseases are character ised by a deficiency in antigen specific host T cell responses. We hav e studied the effect of Picroliv, a standardised fraction of root and rhizome of Picrorhiza kurroa, on proliferative T cell response to the mycobacterial 'Purified Protein Derivative (PPD) ' antigen in subjects infected with or exposed to mycobacteria (tuberculoid leprosy patient s and endemic normals). Coculture of their peripheral blood mononuclea r cells with the optimal concentration of Picroliv (0.5 mu g/ml) signi ficantly enhanced the proliferative response to 1/10 optimal PPD dose, as determined by [H-3] thymidine incorporation, in the group of 'low' responders. The response to PPD of cells from `high responders' and t o PHA (phytohaemagglutinin, a non-specific T cell mitogen) remained un affected by Picroliv which did also not induce cell proliferation on i ts own. The selective, antigen specific augmentation of human T cell r esponse suggests that Picroliv could be useful as an adjunct to chemot herapy or as a short term prophylactic agent.