Generation of human plaque-forming cells in culture: tissue distribution, antigenic and cellular requirements

A system for the induction of specific, hemolytic plaque-forming cells from normal human lymphocytes in vitro (HcPFC) has been established and cells from various normal lymphoid tissues have been investigated. Normal values for anti-SRBC HcPFC responses in cultures of 107 Ficoll-Hypaque separated lymphocytes range from 2000 (bone marrow) to 7000 (spleen) and 15,000 (tonsillar and peripheral blood lymphocytes). HcPFC responses to ovalbumin were lower by factor of 2 to 4. Anti-SRBC as well as anti-ovalbumin responses required the cooperation of T lymphocytes and IgM-bearing B lymphocytes and the magnitude of the response was antigen dose dependent. Addition of adherent cells as well as of 2-mercaptoethanol enhanced the response. On the basis of the data obtained in experiments examining the role of B and T lymphocytes, a tentative model of cellular interaction has been postulated, suggesting a major role for antigen concentration in the modulation of the response via reactive T lymphocytes.