Responses of 'mature' human B lymphocyte lines to inducers of maturation and activation

Four human B cell lines with a mature phenotype (immunoglobulin secretion and expression of membrane markers associated with maturation) were cultured in the presence of phorbol ester (PMA), dimethyl sulphoxide (DMSO) and two conditioned media. PMA and DMSO led to changes in phenotype which suggested the cells were being activated, whilst the conditioned media resulted in increased immunoglobulin secretion, accompanied by phenotypic changes more consistent with maturation towards the plasma cell stage. The four cell lines, which had different origins (EBV-transformed normal B cell, Burkitt's lymphoma, prolymphocytic leukaemia and multiple myeloma) responded differently to the culture stimuli. These differences suggest that the changes associated with transformation affect the way in which these cells respond to agents which stimulate activation and maturation.