The role of B and T lymphocytes in forming cell clones producing antibodies

Abstract

Previous experiments with cloning of immunocompetent cells indicate a switch from IgM to IgG during the multiplication of immunologically activated cells derived by proliferation from one precursor. An alternative explanation, cooperation of one T cell with two different B cells (IgM and IgG precursors) is experimentally studied in the present work. Control experiments indicate that all detected foci are dependent on the production of antibodies and the action of complement. Numbers of foci are linearly dependent on the quantity of cells transferred to isologous lethally irradiated mice. There is a time gap between the first detection of antibodies by the focus technique (on the 4th day after the transfer) and by the plaque technique with isolated cells (detectable only from the 6th day after the transfer); early foci contain antibodies but do not produce (secrete) them in sufficient amounts. Transfer of lymphocytes isolated from spleen, bone marrow and thymus showed that foci in the primary response are formed only by B lymphocytes. The transfer of a constant number of B lymphocytes with increased numbers of T lymphocytes did not change the quantity of Ab-forming foci; there is an increase, however, of the numbers of individual cells producing antibodies detected by the plaque technique,i.e. the number of Ab forming cells per individual clone (focus). Through the action of T lymphocytes the switch from IgM to IgG is made possible. The auxiliary role of T lymphocytes in the primary response is discussed.