Induction of the insulin receptor and other differentiation markers by sodium butyrate in the Burkitt lymphoma cell, Raji.

The very low expression of insulin receptors in the Burkitt lymphoma cell Raji was increased 2-fold, 6-fold and 10-fold after 1, 2 and 3 days, respectively, by incubation with the differentiation inducer sodium butyrate. Insulin receptor number was increased without a change in receptor affinity, in association with an increase in the receptor alpha and beta subunits detected after cell-surface labelling and immunoprecipitation. Expression of cell-surface class I and II human leukocyte antigens, the intercellular adhesion molecule-1 and the CD38 leukocyte antigen was also increased, consistent with B cell differentiation. Butyrate effects were not unspecific, as the binding of tumour necrosis factor and growth hormone and the expression of the B cell markers CD20, B5 and CD21 was not increased. The low expression of insulin receptors on Raji cells is therefore a reflection of the less differentiated state of these cells compared to lymphoblastoid cells.