Peanut agglutinin: a marker for normal and leukaemic cells of the monocyte lineage.

The potential of peanut agglutinin (PNA) as a monocyte lineage marker and a diagnostic tool was investigated. Peripheral blood mononuclear cells (MNC) from normal adults, and 20 patients with acute non-lymphocytic leukaemia (ANLL), as well as five human cell lines were analysed for fluorescein isothiocyanate (FITC)-PNA binding using the fluorescence activated cell sorter (FACS). Monocytes and monoblasts, which were positive for non-specific esterase activity, bound FITC-PNA. In addition, FITC-PNA was bound by a population of cells not defined by cytochemical criteria which were probably precursors to monoblasts. The classical myeloid blast cell did not bind FITC-PNA. ANLL classification is discussed in the light of these results. FITC-PNA clearly binds to cells of the monocyte lineage, and has potential as an adjunct to current cytochemical and morphological criteria in classification.