栄養状態の変化と生体防衛因子, 特に補体の変動に関する応用的研究

抄録

To break the vicious circle between malnutrition and severe infection which has been linked to the great majority of infant deaths worldwide, we have been conducting clinical and experimental studies to search for measures which provide rapid enhancement of body defenses. Based on animal experiments and clinical observations of malnourished states, it appears that nutritional deprivation affects various components of the body's defense system to various extents, cell-mediated immunity (CMI) being the most susceptible. The complement system acts to maintain host defense even when CMI is impaired. Also observed was the earlier recovery of serum complement to normal or higher levels as compared with that of CMI. The complement system responded to bacterial infection much earlier than other immunological responses, even in malnourished rats with depressed CMI. The infected rats showed a much higher rate of de novo synthesis of complement proteins than noninfected rats, and this effect was predominant in the malnourished group. Based on these experiments, we attempted to induce rapid heightened resistance to infection in malnourished rats by enhancing the complement system. After administration of lentinan or chlorophyllin, which are known to activate C3 in vitro, heightened resistance to bacterial infection was induced together with a heightened complement response. These activators enhanced C3b formation and iC3b formation in vivo, eventually resulting in enhanced interaction of iC3b present on invaders with CR3 on phagocytic cells.