Affilications: *Health Sciences Research Institute
**Division of Medicinal Plant Research and Development, Department
of Medical Sciences, Ministry of Public Health, Bangkok 11000,
Source: Thai Journal of Pharmaceutical Sciences 1996; 20(4): 261-267
The extract of Clinacanthus nutans has been used for the treatment against a variety of symptoms from either infectious or non-infectious agents. Less has been known for its activity on the immune system. Human immunocompetent cells were used to study the role of C. nutans extract in modulating cell-mediated immune response (CMIR) in vitro. We investigated the effect of C. nutans extract on lymphocyte proliferation, function of natural killer (NK) cells, and production of interleukin-2 (IL-2) and interleukin-4 (IL-4). Lymphocyte proliferation was significantly increased at the concentrations of 0.5, 2.5, and 5 mg/ml, while the response was significantly reduced at 2.5, and 5 mg/ml of C. nutans extract.The activity of NK cells was significantly decreased at the concentrations of 1 and 5 mg/ml. Furthermore the level of IL-2 released from C. nutans treated-mononuclear cells was undetectable, whereas that of IL-4 was shown to be induced by the extract at the concentrations of 2.5 and 5 mg/ml. These data suggested that the effect of C. nutans on human CMIR in vitro may be partially due to the release of IL-4 from peripheral blood mononuclear cells.