Detection of BLT substrate-specific proteases in individual human peripheral blood leucocytes and bone marrow cells. Application of the method to the classification of leukaemia.

A trypsin-like serine esterase (SE) is known to be present in cultured cells with cytolytic potential. The distribution pattern of this enzyme in haematological cells and body tissues has been assessed using a method which permits rapid identification of individual cells. Cells and tissue sections were fixed and immersed in the substrate N alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester (BLT)/Fast Blue BB chromogen solution. To identify the phenotype of SE+ cells the cytochemical stain was followed by the application of monoclonal antibody and alkaline phosphatase-anti-alkaline phosphatase (APAAP) complex immunocytochemical procedures. CD8+ and CD57+ lymphocytes showed SE+ granules. Neutrophil granulocytes and progenitors other than undifferentiated myeloblasts developed a dense stain while eosinophils were negative. 35% of monocytes showed positivity mainly in the area of nuclear indentation. Tumour-infiltrating SE+ lymphocytes could also be demonstrated with this method.

Splenic irradiation as primary therapy for prolymphocytic leukemia.

A patient with prolymphocytic leukemia (PLL), a lymphoproliferative disorder that carries a poor prognosis, is presented. The disease was diagnosed at an early stage and treatment could be delayed for four years. When massive, painful splenomegaly developed, splenic irradiation (SI) was chosen as the primary form of therapy and an excellent systemic response could be achieved. Our observation is in agreement with preliminary studies, which advocate SI as the primary form of therapy in PLL. Furthermore, it is emphasized that an early diagnosis of PLL is necessary to establish its true course and that the prognosis may be better than originally thought.