Biological activity of the pure thymus protein, LSHr

LSHr, a protein from thymus, was shown to be a single pure peptide of 80,000 daltons by its migration in Sephadex G-150, SEDImentation velocity ultracentrifugation, both regular and SDS gel electrophoresis, and isoelectric focusing as a single symmetrical peak. It promoted the differentiation of T-lymphocytes in in vitro and in vivo tests. Human bone marrow cells showed differentiation in response to LSHr treatment to express a surface marker unique to T-cells following incubation with 10(-14) to 10(-9) M LSHr. Control proteins showed no effect. In preliminary experiments, administration of microgram quantities of LSHr to nude mice for 2-3 weeks induced development of T-cell function as determined by antibody response to a T-dependent antigen, and a response of spleen cells to T-cell mitogen.