IS CONCOMITANT HIGH CD7 AND LOW PRB EXPRESSION ASSOCIATED WITH CENTRAL-NERVOUS-SYSTEM INVOLVEMENT IN ACUTE-LEUKEMIA

Background - Central nervous system (CNS) involvement is an adverse pr ognostic factor in potentially curable leukemic patients and a frequen t feature in certain CD7(+) acute leukemias, Our aim was to investigat e whether low expression of retinoblastoma gene product (pRB) and high expression of CD7 could have any association with CNS involvement in acute leukemias. Methods - Blast-enriched peripheral blood from five a cute leukemic patients with CNS involvement, including two AML, two T- ALL, and one CML-blastic crisis (BC), and of 40 patients without CNS i nvolvement, including 32 AML, three B-ALL, and five T-ALL, were analyz ed for CD7 expression by flow cytometry and for pRB expression by immu nocytochemistry. Results - Of 45 patients, 11 (24%) had low pRB expres sion (six AML, three T-ALL, one B-ALL, and one CML-BC) and 11 (24%) ha d CD7 (>25%) expression (3 AML, 7 T-ALL, and one CML-BC). Of 45 patien ts, five (11%) revealed CNS involvement at relapses, Concomitant low p RB and high CD7 (>70%) expression was observed in these five patients at diagnosis, while only one out of 40 patients without CNS disease re vealed low pRB and high CD7 expression concomitantly (p<0.000005). Con clusion - Patients with low pRB associated with high CD7 (>70%) expres sion warrant further studies to evaluate CNS involvement in acute leuk emia.