Fetal thymidine kinase (TK1) in hairy cell leukaemia.

The thymidine kinase isoenzyme profile was determined in peripheral blood mononuclear cells and splenic tissue from 4 patients with hairy cell leukaemia, in order to assess the proliferative state of the hairy cell. The predominance of TK1 activity in all 4 spleens and in 2 out of 3 peripheral blood mononuclear cells examined, indicates that the hairy cell has significant proliferative capacity when compared to the neoplastic cell in other chronic lymphoproliferative disorders. It is suggested, in view of the heterogeneity in peripheral blood mononuclear TK isoenzyme types, that more extensive studies are warranted to examine the relationship between peripheral blood mononuclear TK1 activity and the occurrence of progressive disease in post-splenectomy patients.