Echinocytic sensitivity and deformability of human newborn red cells.

Echinocytic red cells are present in the peripheral blood of normal human newborns in small but significant numbers. This is in contrast to normal adults in whom no echinocytes are found in peripheral blood. In addition, red cells from newborns have increased susceptibility to echinocyte transformation induced by naturally occurring phospholipid lysolecithin. The mechanism for this increased susceptibility does not appear to be related to the lipid composition of these cells. Cellular deformability of red cells from newborns, as determined by a newly developed viscodiffractometric technique, is similar to that of adult red cells. This finding differs from an earlier report of reduced deformability of fetal red cells.