Development of immunity

Infants born before 28 weeks gestation have low lgG levels which then fall further. Newborn infants have less effective polymorphonuclear chemotactic movement than adult cells. These defects are more marked in preterm infants and presist for longer. C3 C4 and complement factor B are signficantly lower before 32 weeks than at term and in infants born at 27 weeks C3 and C4 are persistently low. Opsonic activity against Staphlococcus epidermidis decreases with decreasing gestational age. Septicaemic very immature infants are liable to develop neutrophil storage pool exhaustion. The multiple immune deficiencies in infants born before 28 weeks render them extremely vulnerable to bacterial invasion. Replacement therapy with immunoglobulin is now of proven value. Granulocyte transfusion or exchange transfusion are both logical but lack consistent confirmation as therapies. Active immunisation can be carried out as usual even in the most immature infants.