A new approach of acute lymphoblastic leukemia immunophenotypic classification: 1984-1994 the GEIL experience. Groupe d'Etude Immunologique des Leucémies.

Several classifications of acute lymphoblastic leukemias (ALL) have been proposed as increasing numbers of technologies and reagents allowed to better characterize leukemic tumor cells. The French Groupe d'Etude Immunologique des Leucémies (GEIL) proposes an immunologic classification of ALL derived from this group's initial attempts and on proposals published by others. Its first step is based on a scoring system where individual markers are assigned major, intermediate and minor weights on a scale of respectively 1.5, 1 and 0.5 points. Assignment to a given lineage requires a score of at least 2 in this lineage. Thus are identified the four levels "null", "pure", "variant" and "multiphenotypic", depending on score combinations in the three B, T and myeloid lineages. In a second step, within each of these classes, cell differentiation criteria are applied to further identify 4 subclasses within PreB-ALL (PreB1 to PreB4) and 4 within T-ALL (T1 to T4). ALL with only myeloid markers are referred to as M0. This classification was applied to a series of 1014 scorable ALL. Pure ALL represented respectively 72% in children under 16, and 64% in adults, PreB ALL being significantly more frequent in the former (p < 0.01). B-ALL and T-ALL were significantly (p < 0.05) more frequent in adults (respectively 11% and 27%) than in children (7% and 20%). Null and M0 ALLs appeared significantly (p < 0.01) more frequent in adults (3.4 and 3.2%) than in children (1 and 0.3%).(ABSTRACT TRUNCATED AT 250 WORDS)