title: Antibody-forming foci in soft-agar cultures of human peripheral blood cells.
abstract: Human peripheral blood lymphocytes (PBL) from healthy blood donors were grown in soft-agar gel with sheep red blood cells (SRBC) and autologous plasma as a source of complement. After 4--6 days incubation, foci of proliferating hemolysin-forming cells, surrounded by a lytic area of 0.2--0.5 mm, were detected on the surface of the plates. The response was antigen specific, since new hemolytic areas were observed on pouring a fresh agar-SRBC mixture over the surface of primary cultures, but not on pouring a mixture containing rat or rabbit erythrocytes. The antibody response was significantly increased by addition to the cultures of polyethylene glycol 6000 (PEG), 8% final concentration. The mean number of foci was 8.4 +/- 2.2 in cultures without PEG and 36.2 +/- 2.3 in PEG+ cultures, both containing 9 X 10(6) lymphocytes. This finding is in agreement with observations on the frequency of precursors of antibody-forming cells among lymphoid populations. The explanation of the mechanism by which PEG 6000 modified the immune reactivity of PBL is not clear. However, we think, that this technique provides a reliable methodology for PBL antigenic stimulation in vitro.
mesh_terms: D000362:Agar; D000818:Animals; D000921:Antibody-Producing Cells / Q000276:immunology*; D001773:Blood Cells; D002478:Cells, Cultured; D006461:Hemolysis; D006801:Humans; D007124:Immunoenzyme Techniques; D007075:Immunoglobulin M; D011092:Polyethylene Glycols / Q000494:pharmacology; D011817:Rabbits; D012756:Sheep; D013997:Time Factors
chemical_list: D007075:Immunoglobulin M; D011092:Polyethylene Glycols; D000362:Agar