Expression of ICAM-1 (CD54) on normal and leukaemic B cells: implication for the mixed lymphocyte reaction.

Peripheral blood normal B lymphocytes were found to be poor stimulators in the mixed lymphocyte reaction (MLR), in contrast to normal activated B cells which were strong stimulators. This increased capacity to stimulate a strong MLR correlated with an increased expression of the ICAM-1 (CD54) molecule on the surface of these cells. Similarly, the capacity of leukaemic B cells to induce an allogenic stimulation in the MLR was limited to the ICAM-1 (CD54) positive leukaemic cells. The ability of normal activated or leukaemic B cells to induce an MLR was blocked by antibodies directed against ICAM-1.