Monocytes in children with leukemias and lymphomas -- down-regulation of HLA and costimulatory molecules.

The aim of the study was to evaluate the function of monocytes in children with leukemias and lymphomas based on the expression of critical costimulatory, activatory and adhesion molecules (CD80, CD86, HLA-DR and CD54 = ICAM-1), estimated with tricolor flow cytometry. In comparison to the control group we found a lower percentage of monocytes with costimulatory molecules (CD80 before and CD86 after lipopolysaccharide stimulation) at the time of diagnosis and of monocytes with HLA-DR molecules after remission induction. We also noted a lower percentage of monocytes with HLA-DR expression in the group with severe or therapy resistant infections. The results of our investigation suggest some defect in costimulation and antigen presentation in lymphoproliferative diseases in children.