The demonstration of terminal deoxynucleotidyl transferase on frozen tissue sections and smears by the avidin-biotin complex (ABC) method.

A method using avidin-biotin complex (ABC) to detect the presence of the enzyme terminal deoxynucleotidyl transferase (TdT) is described and compared with a proven indirect immunofluorescence method. The material studied consisted of: (1) peripheral blood and bone marrow smears from 17 patients with leukemia (ALL, 8; CLL, 3; AML, 6), six normal controls, one T-ALL cell line, and (2) frozen tissue sections from four patients with lymphoblastic lymphoma (LL), two patients with nodular poorly differentiated lymphocytic lymphoma (NLPD), two patients with reactive follicular hyperplasia (RFH) and one calf thymus. The slides from patients with ALL had from 30 to 90% cells with nuclear positively by the ABC technique. Slides from patients with CLL were negative, as were the normal peripheral blood smears. Normal bone marrow smears contained less than 5% positive cells. The T-ALL cell line was 100% positive. The frozen tissue sections from the patients with LL and the calf thymus contained numerous positive cells, while all of the sections from the patients with NLPD and RFH were negative. A good correlation existed between the ABC and the indirect immunofluorescence methods. The ABC method described is both more specific and more sensitive than the previously described techniques in detecting TdT in tissue sections and smear preparations.