FLOW CYTOMETRIC TERMINAL DEOXYNUCLEOTIDYLTRANSFERASE ANALYSIS - EVALUATION OF TRITON X-100 AND METHANOL PERMEABILIZATION METHODS COMPARED WITH IMMUNOFLUORESCENCE MICROSCOPY

We evaluated the detection of terminal deoxynucleotidyltransferase by flow cytometry using two commonly reported methods of permeabilization and compared them with immunofluorescence microscopy. Thirty-four con secutive cases referred for leukemia workup were studied prospectively . We found decreased viability of cells with both flow cytometry metho ds in association with shifts in forward and side scatter patterns. Bo th procedures demanded careful manipulation of cells to avoid total ly sis. The Triton X-100 method had a sensitivity of 100% and a specifici ty of 93%, while the methanol method had a sensitivity of 54% and a sp ecificity of 100%. Therefore, the Triton X-100 method correlated bette r with immunofluorescence microscopy than did the methanol method. Des pite technical difficulties, the advantages of increased objectivity, increased diagnostic capability associated with multicolor analysis, a nd the increased sensitivity in detecting minimal residual disease mak e flow cytometry a more attractive and advantageous procedure.