Adhesion molecule expression, clinical features and therapy outcome in childhood acute lymphoblastic leukemia

In view of the relevance of adhesion molecule expression fur the mechanisms of homing, trafficking and spreading of malignant cells, we have investiga ted the expression of surface adhesion molecules in lymphoblasts from 57 ac ute lymphoblastic leukemia (ALL) caves and tried to correlate the adhesive phenotype with immunological typing, prognostic factors at diagnosis and cl inical follow-up. Blasts from all cases expressed adhesion molecules at hig h rates. beta (1) integrin chain (CD18) was consistently found on blasts fr om most ALL cases; among integrins of the beta (2) family, LFA-1 was detect ed in 58% of cases, in the virtual absence of other a chains. CD54 and CD58 were expressed in variable proportions by ALL blasts and CD44 was detected in the majority of the malignant cells, whereas the CD62L selectin was onl y present in 24% of cases. B-lineage ALL's. displayed similar adhesion mole cule phenotypes irrespective of maturational stages of the leukemic cells. We found a significantly reduced expression of beta (2) alphaL integrins in the hybrid ALL cases (CD13 and/or CD33 positive). However. these cases did not show differences in clinical presentation and behaviour in comparison with patients of other groups. We did not iind a significant correlation be tween adhesion molecule expression and well established risk factors (age, white blood cell count, central nervous system involvement, chromosomal abn ormalities), with the exception of splenomegaly. that was significantly ass ociated with CD18 expression. In the follow-up, no evidence of significant correlation between adhesive phenotype and adverse events such as leukemic relapse and death was found. In conclusion, although expression of adhesion molecules on lymphoblasts confirms the phenotypic heterogeneity of ALL, it appears that this is not relevant for the clinical aspects of the disease and for prognosis.