Flow cytometry in the diagnosis of acute leukemia.

Fifty cases of acute leukemia were analyzed by means of flow cytometry. The results obtained were correlated with morphology and routine cytochemistries. The panel selected was useful in classifying an acute leukemia as acute lymphocytic (ALL) or acute nonlymphocytic (ANLL), which is of primary importance for therapeutic considerations. Common ALL (CALLA) (J5) was a good marker for classifying the leukemia as ALL. Monoclonal antibodies (MoAbs) T1 and/or T11 further delineated the lymphoid leukemia as T-cell ALL while MoAbs B4 or B1 delineated the lymphoid leukemia as non-T-cell ALL. Eighteen cases of ALL were diagnosed and consisted of five cases of T-cell ALL and 13 cases of non-T-cell ALL. Both the T-cell ALL cases and non-T-cell ALL cases were found to be heterogeneous and could be further subgrouped by phenotypic expression with additional MoAbs in the panel. A monoclonal antibody panel consisting of My4, My7, My9, Mo1, and Mo2 was useful in characterizing an acute leukemia as ANLL. This panel was less useful in distinguishing myeloid from monocytic subtypes although My4, Mo1, or Mo2 when present, appeared to favor a monocytic component. Of interest, a case of biclonal leukemia with two distinct blast populations on the flow cytogram was discovered. Morphology alone was successful in diagnosing ALL from ANLL in 35 cases (70%). It was not useful in distinguishing non-T-ALL cases from T-ALL cases. The ambiguous cases could be resolved by cytometric means. Flow cytometry has much to offer as a diagnostic aid in the evaluation of acute leukemia.