Expression of CD20 on acute lymphoblastic leukemia cells in children.

CD20 determinant expressed on B precursors is associated with regulation of proliferation, apoptosis and maturation of these cells. The acute lymphoblastic leukemia "common" type (cALL) based on expression of CD20 is subdivided in type I and II. However, the clinical significance of CD20 expression on cALL and significance of cALL type I and II discernment are not fully elucidated. The association of CD20 expression with the expression of multidrug resistance molecule (MDR), CD34, atypical immunophenotypes of leukemia cells and response to induction therapy were determined in the group of 147 patients with acute lymphoblastic leukemia (ALL) B progenitor type (ALL-proB -14 patients) and common type (cALL-133 patients). The expression of CD20 on leukemia cells was studied routinely at diagnosis before the therapy. This expression was noted on leukemia cells of 6 ALL-proB patients (42.8%) and 66 cALL patients (49.6%). The expression of CD20 showed no association with the expression of CD34, CD22 and MDR. The reverse association was observed between CD20 expression and the presence of co-expression of myeloid (CD13, CD33, CD65, CD15) and T lymphoid determinants (CD2, CD5, CD7) on leukemia cells. The effect of induction therapy analyzed as time of blast cells cytoreduction in peripheral blood and time of reaching the complete remission showed the slower clearance of peripheral blood from blast cells associated with expression of CD20. There was no association of CD20 expression with the time of reaching the hematological remission. The above results suggested a "protective" role of CD20 against co-expression of other determinants (myeloid and lymphoid) and no association with the results of induction therapy.

Changes in the phagocytic cells in children treated with continuous ambulatory peritoneal dialysis.

Children on continuous ambulatory peritoneal dialysis (CAPD) in endstage renal failure are highly exposed to peritonitis. Peritoneal macrophages (PM) and blood neutrophils (PMNC) are the first line of defense against invading microbes. This study was undertaken for assessing surface receptors expression on PM and PMNC and to check their ability to phagocytosis and killing of bacteria. We have found that in spite of the decreased number of PM in dialysate fluid their viability and activity significantly increased during CAPD. Moreover, higher number of PM expressed CD16 and CD35 antigens (FcRIII and C3bR, respectively) in comparison with the results observed at CAPD onset. The number of PMNC expressed of these two antigens in uremic children blood were significantly lower in comparison with healthy control. The number of CD16 positive cells increased under influence of CAPD only temporarily. CAPD caused improvement of phagocytosis and intracellular killing of bacteria by PM but not by PMNC. There is discussed here influence of uremia and CAPD on surface antigens, function of phagocytes as well as renewal of PM during CAPD.