Flow cytometric detection of CD10 (cALLA) on peripheral blood B lymphocytes of neonates

CD10 (cALLA) was detected on the surface of CD19‐positive circulating lymphocytes in the peripheral blood of 32/50 neonates tested. These cells are presumed to represent immature B cells, commonly referred to as haematogones, previously undescribed in peripheral blood. The CD10+/CD19+ cells expressed lower levels of CD22 consistent with these cells being immature B lymphocytes. The presence of CD10+/CD19+ cells in the blood was not significantly correlated with a leucoerythroblastic picture, adjusted gestational age, or the presence in blood smears of medium‐to‐large lymphocytes with an immature appearance that morphologically resembled classic bone‐marrow haematogones.