Human lymphocyte markers defined by antibodies derived from somatic cell hybrids. III. A marker defining a subpopulation of lymphocytes which cuts across the normal T-B-null classification.

A somatic cell hybrid line which secreted antibody reacting selectively with a proportion of the white cells in human blood was prepared. The hybridoma appeared to be monoclonal, and the antibody secreted stained 67% of the lymphocyte population in blood. It reacted less well with granulocytes and monocytes. The lymphocytes stained comprised 80% of the T cells and 50% of the B cells. The antibody showed no recognizable pattern in its reactivity with cell lines and leukaemic cells, although B cells tended to react less well than T cells, null cells, or myeloid leukaemic cells. The expression of the antigenic determinant is discussed in relation to the classification of leucocytes. This determinant and certain other markers exhibited differential expression on closely related cells, and yet were shared by more distantly related cells.