Expression of Ia-like antigen in lymphatic leukaemias and non-hodgkin lymphomas in correlation with other surface markers.

Ia-like antigen, surface Ig, E-rosettes, mouse red blood cell rosettes and further surface markers were investigated in 88 specimens from 69 patients with various lymphocytic leukaemias and non-Hodgkin lymphomas. Ia-like antigen was detectable in all cases of sIg+ leukaemias and lymphomas. E-Ia+sIg-leukaemias, especially CLL and lymphomas were interpreted as B-cell neoplasias, which either did not produce sIg or expressed it in undetectable amounts. E+Ia+sIg+ malignant lymphocytes represented a B-cell population with antibody activity of sIg to SRBC. In the present series 9.5% of all B-cell leukaemias and lymphomas demonstrated this phenotype. Whereas ALL may possess Ia-like antigen, the vast majority of mature T-cell lymphomas are lacking it. In the present series 2 T-cell lymphomas expressed Ia-like antigen and did not contain TdT (E+Ia+sIg-TdT-). These lymphomas are probably derived from a stimulated T-cell clone synthesizing Ia-like antigen.