Immunomodulatory potential of ethanol extract of spilanthus acmella leaves

Aims: Ethanol extract of leaves of Spilanthes acmella (SAEE) was evaluated for its immunomodulatory potential using various models like neutrophil adhesion (NA) test, haemagglutinating antibody (HA) titre and delayed type hypersensitivity (DTH) response in rats. Methods: The coarse powder (40-mesh) of shade dried leaves (500g) of Spilanthes acmella was subjected to maceration using 95% ethanol. Preliminary phytochemical tests were conducted for SAEE to identify the various phytoconstituents. Two doses of SAEE were selected and SAEE was administered orally at doses of 250 mg/kg body weight and 500 mg/kg body weight to healthy rats. The assessment of immunomodulatory potential was carried out by testing the humoral (antibody titre) and cellular (foot pad swelling) immune responses to the antigenic challenges with sheep RBC (SRBC) and by neutrophil adhesion test. Clean tap water was served as a control in all the tests. Results: Orally administered SAEE showed a significant increase in neutrophil adhesion, haemagglutinating antibody titre (HAT) and delayed type hypersensitivity (DTH) response. In rats immunized with sheep RBC, SAEE enhanced the humoral antibody response to the antigen and significantly potentiated the cellular immunity by facilitating the footpad thickness response to sheep RBC in sensitized rats. With a dose of 500 mg/kg body weight the values of NA, HAT and DTH responses were statistically significant as compared to control. Conclusion: The study demonstrates the immunomodulatory potential of Spilanthes acmella in rats. The responses were statistically significant when they were compared to control.