Primary in vitro anti-KLH antibody formation by peripheral blood lymphocytes in man: detection with a radioimmunoassay.

In the present report, a primary in vitro human antibody response to KLH was investigated. Peripheral blood lymphocytes were incubated with antigen for 5 days and then cultured in the absence of KLH for 4 additional days. Maximal anti-KLH antibody production, as measured by radioimmunoassay, occurred at a cell density of 1 X 10(6) and at an antigen concentration of 5 micrograms per culture. The antibody produced was shown to be predominantly of the IgM isotype and specific for KLH antigen in several binding assays. Moreover, no antibody was generated in the absence of T lymphocytes. This in vitro antibody-forming system should be of considerable use in the analysis of the cellular requirements for antibody production and the genetic control of the immune response in man.