In vitro response to rosette inhibition factor (RIF) and rosette restoring factor (RRF) of human lymphocyte after fractionation on a discontinuous density albumin gradient.

In vitro studies on peripheral blood lymphocytes from tuberculous patients and healthy subjects are reported. Factors isolated from human serum used in the experiments included the Rosette Inhibition Factor (RIF) from serum of tuberculous patients and the Rosette Restoring Factor (RRF) from serum of healthy subjects. Lymphocytes were fractionated on a discontinuous BSA gradient. Lymphocytes from healthy subjects, sensitive to RIF, as well as lymphocytes from tuberculous patients, sensitive to RRF, were localized in the third fraction of the BSA gradient. A small percentage of bone marrow cells upon coming into contact with RRF spontaneously formed rosettes with SRBC and were also localized in the third fraction after centrifugation in discontinuous BSA gradient. The results indicate that RIF and RRF act on the same subpopulations, probably precursors of T cells.