Neutrophil phenotypic characteristics in children with congenital asplenia and splenectomized for hereditary spherocytosis.

The spleen plays an important role in the granulocyte homeostasis due to such mechanisms as pooling, elimination of senescent cells and regulatory effects on granulocyte renewal in the bone marrow. The expression profile of granulocyte receptors was tested in children with congenital asplenia, and splenectomized for spherocytosis. Receptors tested included those appearing with maturation (CD16, CD11b, CD11c, TREM-1), disappearing (CD54, CD49d, CD64) and maintained during maturation (CD11a, CD45). In general, we found that the circulating granulocyte pool in the asplenic patients had phenotypical features of highly matured but not apoptotic neutrophils with a significantly elevated expression of CD16 (CD16(high)), tendency to a lower expression of CD45 (CD45(low)) and an unchanged expression of CD64 (and other markers indicating systemic inflammatory reactions). The high fluorescence intensity of CD11b,c, and TREM-1 in the congenital asplenia may indicate a potentially elevated pro-inflammatory status of granulocytes, possibly due to the low activity of vagus nerve and spleen-dependent cholinergic anti-inflammatory pathway.