Quantitative cytology in leukemia research

A study was undertaken to determine the usefulness of flow cytometric analysis of bone marrow cells as an objective means for diagnosis, classification and prognosis in patients with leukemia. Abnormal DNA content as a marker of neoplastic disease was found in only 15% of 264 adult patients with acute leukemia (13% in AML, 26% in ALL/AUL). Alternative means of tumor cell detection in heterogeneous marrow samples include determination of nucleolar antigen density and double-stranded RNA content. Phenotypic characterization of leukemia subtypes can be afforded by RNA content analysis of acridine orange-stained cells, demonstrating significantly higher mean RNA content values in AML, compared to ALL/AUL. Cytokinetic parameters amenable to flow cytometric analysis include measurements of cell cycle compartment distribution by DNA content, of cycle traverse rate by BUdR-induced modification of fluorescence intensity of DNA specific dyes and of growth fraction employing the method of in situ DNA denaturation and subsequent acridine orange staining. Determination of cell cycle distribution and RNA content pretreatment and serially during remission induction in 82 patients demonstrated a significantly lower pretreatment biopsy S phase proportion in responding patients with AML compared to individuals failing treatment whereas an opposite trend was noted in patients with ALL/AUL. While of no prognostic impact pretreatment, serial determinations of the RNA content during the first chemotherapy induction course revealed significant differences between responding and failing patients with AML. Also, patients attaining remission demonstrated a rise in marrow biopsy S phase compartment size by day 10 to 14 of treatment, thus, predicting remission during marrow hypoplasia. We conclude that quantitative cytologic examination of marrow cells from patients with acute leukemia provides useful diagnostic and prognostic information that should aid in the stratification of patients with poor prognosis to receive new agents.