An Ia-like antigen positive null cell leukemia cell line (THP-5) lacking in the stimulating capacity in autologous and allogeneic mixed lymphocyte reaction.

A null cell leukemia cell line, THP-5, was established from the peripheral blood of a patient with acute null cell leukemia. THP-5 cells were characterized by the presence of Ia-like antigen and the absence of other cell surface markers examined. Despite the presence of Ia like antigen, THP-5 cells had no stimulating capacity in autologous or allogeneic mixed lymphocyte reaction.