SUPPRESSION OF ADULT B-CELL DIFFERENTIATION IN POKEWEED MITOGEN-STIMULATED CULTURES BY FC(IGG) RECEPTOR-NEGATIVE T-CELLS FROM CORD BLOOD

Abstract

Unfractionated T [thymus derived] lymphocytes from cord blood suppressed adult B [bone marrow derived] cell differentiation into immunoglobulin-producing cells in pokeweed mitogen-stimulated co-culture system. Cord blood T cells were fractionated into T cells bearing Fc [immunoglobulin fragment] receptors for IgG(T.gamma. cells) and T cells lacking Fc receptors for IgG(Tnon-.gamma. cells) by rosette formation with ox erythrocytes coated by the IgG fraction of rabbit antisera followed by Ficoll-Hypaque gradient sedimentation. T.gamma. cells from cord blood, even though isolated after the interaction with immune complexes, showed no suppressor activity on adult B cell differentiation, whereas Tnon-.gamma. cells exerted strong suppression to a similar extent to that by unfractionated cord T cells. The suppressor activity on B cell differentiation by Tnon-.gamma. cells as well as by unfractionated T cells from cord blood was completely abrogated by irradiation with 2000 rads. Contrary to suppressor function found in adult T cells the suppressor activity in cord T cells might be exerted by a T cell subset lacking Fc receptors for IgG(Tnon-.gamma. cells).