Parameters affecting in vitro immunization of human lymphocytes.

A method for the in vitro generation of antibody-secreting cells from human tonsil lymphocytes is described. Several parameters affecting such in vitro immunization have been studied in order to define optimal conditions for the production of specific antibody. In the presence of 15% of T-cell growth factors, lymphocytes prepared by Ficoll-Paque centrifugation increased 2.5 times over a period of 6 days. The major factors triggering specific antibody production against Haemophilus influenzae type b outer membrane preparations were: the use of tonsil lymphocyte cultures instead of peripheral blood lymphocytes, foetal calf serum instead of human serum, T-cell growth factors as a non-specific lymphocyte activator, low concentrations of antigen ranging from 1 to 10 ng/ml, a cell concentration of 4 X 10(6) cells/culture, and finally the removal of OKT8 positive suppressor T-cells. Under these conditions, a maximum antibody production was achieved after 7 days of culture and specific antibody response was obtained after in vitro immunization of tonsil lymphocytes from 10 out of 11 individuals tested.