Nuclear binding of triiodothyronine in human mononuclear cells, and lymphocytes in culture

A method of T3 binding to human mononuclear cells isolated from buffy coat samples is described. Freshly isolated mononuclear cells bind T3 with Ka = 8.6 +/- 1.2 M-1 and Bmax = 6.5 +/- 1.5 fmol/100 micrograms DNA. The preparations of monoclear cells contained up to 25% monocytes, and the binding of T3 to lymphocytes and monocytes was compared after removing the monocytes. On the average, Bmax was slightly higher in monocytes (10.1 +/- 5.8) than in lymphocytes (7.0 +/- 3.2) but the difference was not statistically significant. In some experiments, however, Bmax was clearly higher in monocytes than in lymphocytes. After culturing lymphocytes in Newborn Calf Serum containing medium, Ka decreased and Bmax increased. The T3 binding method described may be used to study the effect of regulatory factors on the T3 receptor in human lymphocytes in culture.