[Chromosome studies in newborn infants following exchange transfusion using countersexual blood]

The chromosomes of 6 (5 females, 1 male) newborns have been examined before and after exchange transfusion. The highest percentage of donor lymphocytes has been found immediately after the exchange transfusion (9%, range 5 to 16%). The percentage of donor lymphocytes had decreased to 4% after 24 hours and to 1% after 3 weeks. There was no hint of a clastogenic effect of phototherapy and exchange transfusion.