Cell-associated and serum beta2-microglobulin was estimated in seven patients with chronic lymphocytic leukaemia. The amount of cell-associated beta2-microglobulin was significantly reduced (P less than 0.01), due to a decrease in the fraction of beta2-microglobulin that passes unretarded through a concanavalin A affinity column (presumably non-HLA-associated beta2-microglobulin). Serum concentrations of beta2-microglobulin were increased, but no correlation was found between the decrease in cell-associated beta2-microglobulin and the increase in serum beta2-microglobulin. All of the beta2-microglobulin from leukaemic serum was eluted corresponding to a molecular weight of 11,800 and none of it was retarded on a concanavalin A affinity column. The decrease in cell-associated beta2-microglobulin might reflect a change in the qualitative or quantitative expression of beta2-microglobulin-associated membrane structures on the leukaemic cells, perhaps conferring resistance to the cells against hypothetical immunological host defence mechanisms.
