Hormone Production by Epithelial Cells of Human Thymus in vitro.

The conditions of hormone production by human thymic stromal cell line were studied. Human thymic stromal cells did not produce any hormones in 5-day monoculture. Co-cultivation of these cells with human thymocytes induced alpha1-thymosin and thymulin production increased to 4-5 days of co-cultivation. An increase in number of human thymic stromal cells and thymocyte elimination were observed in co-culture. The maximal stimulation of proliferation and hormone secretion by human thymic stromal cell was reached in their co-culturing with thymocytes at relative concentrations of 10(4) and 10(7) cells per ml. Thymocyte viability was important for inducing the stimulatory effect. The effect of viable cells could not be replaced by their supernatant. Stimulatory activity of CD4(-)CD8(-) and CD4(+)CD8(+) thymocytes was comparable, alpha1-thymosin and some of its synthetic fragments did not influence alpha1-thymosin synthesis or slightly inhibited it (in high concentrations). Synthetic peptide corresponding to C-terminal half of alpha1-thymosin molecule strongly enhanced production of this hormone.