Activity and characteristics of inflammatory effector cells in newborns

To investigate the aspecific activity of inflammatory effector cells (mononuclear and polymorphonuclear leukocytes) of newborn babies, a comparative study was performed of chemotactic and random filter motility, phagocytic activity, and bactericidal capacity of these cells, of the electron microscopic counterparts of these activities, the serum factors influencing motility and of the content and ratio of cyclic nucleotides present in the cells of subjects of different ages. It was found that chemotaxis of the mononuclear and polymorphonuclear leukocytes is a gradually maturing function; its deficiency observed during the neonatal period is not caused by a depressed excitability by chemical agents, by the presence of inactivators of chemotactic factors or of chemotaxis inhibitors. It is the low serum levels of total complement, C 3, IgG, IgM and properdin that explain the reduced chemotactic mobility. In addition to these factors reduced leukocyte flexibility, condition and activity of the flexibility, condition and activity of the microtubular and microfilamentary system depending on calcium ion and cyclic nucleotide concentrations, and an eventual immaturity or exhaustion of certain intracellular enzymes also play a part. In respect to orientation towards chemical stimuli, the leukocytes of the newborn largely differ from those of children or adults. Similarly, a difference in uptake and elimination of bacteria and in ultrastructural changes accompanying these processes can be demonstrated between newborn and adult cells. The aspecific cellular functions, the reduction of which plays an important part in the weak resistance of the newborn, also depend on certain properties of the infective agents.