正期産児および早期産児の免疫機能

特に, 好中球機能, NK活性, LAK活性, T-cell機能および抗体産生能について

抄録

The survival rate of premature births has improved in recent years due to developments such as that of NICU, but infection still presents a serious risk. The undeveloped nature of neonatal immunological function has been long highlighted, but it can be said without exaggeration that the immunological function which causes simple infection in neonates and in particular premature birth, and its development, are still hardly understood. Study of the quantitative changes in immunologically competent cells such as T-cell, B-cell, and non T-, non B-cells and, furthermore, of the stage when immunological function is acquired, will be not only clinically beneficial in copiing with infection in the newborn nursery, but can increase our knowledge of immunological system ontogenesis. The present study was designed to examine neonatal immunological function, through investigation of neutrophil function, NK activity, LAK activity, T-cells proliferative response to mitogen, their coordinate function antibody generation, and, in addition, cytokine generation in umbilical blood from neonates including miscarried and premature births.
1. Neutrophil function
Phagocytosis in full term births was observed to be the same as in adults but bactericidal function was decreased in comparison to adults. Neutrophil function was first confirmed at 30 fetal weeks, and from 33 weeks onwards obtained the levels seen in full-term births.
2. NK activity
NK activity in full-term births was significantly lower than in adults, however, IL-2-augmented NK activity did not indicate any significant difference with levels in adults. In pre-32 week infants both NK and IL-2-augmented NK activity were further decreased as opposed to in full-term births, suggesting that the first stage of development in NK activity occurs around the 32-week mark.
3. LAK activity
LAK activity was fully developed already in 19 week infants, indicating that auto-monitering of mutant cells is already under control from the early stages of fetal development.
4. Antibody generation
Antibody generation in full-term births and premature births was significantly decreased in comparison to adults, and greatly reduced numbers of helper T-cells, and largely increased numbers of suppressor inducer T-cells as opposed to surface markers were interpreted as indices of decreased antibody generation. Rather than cytokine generation, reduced IL-I generation and diminished BCDF generation were considered to be the causal factors.
From the results it can therefore be concluded that due to the insufficiency of defense mechanisms against infection either bacteriological or viral, transfusion of elements such as granulocytes and administration of immunoglobulin agests should be actively applied in combating serious infection.