Depressive effect of a Taenia solium cysticercus factor on cultured human lymphocytes stimulated with phytohaemagglutinin.

Cysticercosis caused by Taenia solium is associated with immunodepression of T and B lymphocytes. In order to ascertain if this parasite affects lymphocyte activity, a factor isolated from the parasite was tested on (3H) thymidine uptake by cultured human lymphocytes stimulated by phytohaemagglutinin. This dialysable factor had a molecular weight of less than 3500 Da, and was isolated from an extract of Cysticercus cellulosae. It decreased phytohaemagglutinin-stimulated uptake of (3H) thymidine. After the material was treated with RNase 'A', the suppressive activity was destroyed. It thus appears that the factor could correspond to an RNA fraction.