Immunotherapeutic modification of experimental infections by Indian medicinal plants

Secondary infections are the most common cause of mortality in the immunocompromised host. A recent therapeutic approach has aimed at bolstering the host's defence mechanism to assist in eradication of infection, using naturally occurring and synthetic substances like BCG, C. parvum, muramyl dipeptide and glucans. Tinospora cordifolia (TC), Asparagus racemosus (AR) and Withania somnifera (WS) are plants prescribed in Ayurveda, the Indian traditional system of medicine, as agents to strengthen host defence mechanisms. The present article reviews the effects of TC, AR and WS in diverse experimental infections. TC, AR and WS protected rats against caecal ligation induced abdominal sepsis and mice against Escherichia coli peritonitis. This was associated with a faster bacteremia clearance. Myelosuppression induced by single and multiple doses of cyclophosphamide was reversed. Mortality due to Staphylococcus aureus sepsis in neutropenic and hemisplenectomized mice was reduced in treated animals. Candida albicans sepsis induced mortality was also reduced by the plants. The plants induced leucocytosis with predominant neutrophilia associated with stimulation of phagocytic and bactericidal capacity of neutrophils and macrophages. In view of their oral efficacy and relative lack of adverse effects, AR, TC and WS show promise as useful immunomodulators.