Objectives: The aim of this study was to compare, at delivery, the cord blood mononuclear cells of infants with severe hemolytic disease who received intrauterine transfusion (IUT) therapy with the cord blood mononuclear cells of healthy nonimmunized control neonates.

Study design: The expression of leukocyte markers on CBMNC of 14 IUT-treated and 18 control neonates was analyzed by means of a panel of well-defined monoclonal antibodies and flow cytometry.

Results: Patients with severe hemolytic disease requiring IUT treatment displayed significant altered expression of some leukocyte markers when compared with control subjects. The circulating CD34⁺ progenitor cells were significantly increased in comparison with cord blood of nonimmunized neonates. IUT-treated patients also showed a statistically significant decrease in natural killer (NK) cell associated markers (CD16, CD57, and CD69), which correlated with a lower expression of CD56. In these patients an increased expression of CD3/CD45RO and CD3/CD5 was also noted. Although these latter alterations were statistically significant in a single-parameter analysis, the significance disappeared after multi-parameter analysis because of a loss of statistical power.

Conclusions: Compared with nonimmunized healthy newborn infants, patients who underwent IUT also exhibited a down-regulation of NK cells and NK cell associated markers, as well as increased numbers of CD34⁺ progenitor cells.