Plaque-forming cells in man. I. Basic technical results obtained with the protein A technique.

This paper describes the results obtained using an indirect protein A plaque-forming cell (PFC) assay applied to human peripheral blood lymphocytes (PBL) activated with pokeweed mitogen (PWM). A maximal response was obtained after 6 days of culture with regard to the three major classes of immunoglobulin (Ig) investigated. No difference was found between females and males. T and B lymphocytes mixed in ratios varying from 1:8 to 8:1 and unfractionated cells were investigated. A maximal PFC response of isolated lymphocytes was found in cultures of 1:4 T/B reconstituted suspensions of untreated cells, whereas the maximal response of untreated B and 2000-rad-irradiated T lymphocytes was found in cultures with a 4:1 T/B ratio. The number of plaques developed in cultures of unfractionated cells exceeded the response of 4:1 T/B reconstituted untreated lymphocytes but was far below the number of PFC developed in cultures of untreated B and 2000-rad-irradiated T lymphocytes. Normal donors developed approximately 70 X 10(3) PFC/10(6) cells. The viability was 85% after the incubation period. No difference was found in the PFC response of cultures of separated, reconstituted T/B lymphocytes set up in autologous and allogeneic combinations.