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Question: What happens to the immune system in protein malnutrition?


Protein malnutrition deprives the immune system of amino acids that would be used for cellular replication. The immune system response requires that certain cell lines dramatically increase in number. This “feed-forward” mechanism is called clonal expnasion. Neutrophils and macrophages, which phagocytize bacteria and particulate debris, have half-lives of less than 12 hours. The body completely replaces these cells twice daily.

Amino acids are also used for the synthesis of various immune substances. Immunoglobulins (antibodies) are proteins which attach to foreign substances (antigen) and enhance the ability of the neutophil and macrophage to phagocytize the immunoglobulin- antigen complex. They cause killing of bacteria and viruses. Complement proteins facilitate phagocytosis and other processes. Synthesis of these proteins consumes amino acids from the body’s amino acid pools. Normally, the amount scavenged and the amount synthesized is not enough to meet the daily needs. The body depends on dietary protein to keep the amino acid pools at high enough levels to support protein synthesis. If intake is inadequate, the only alternative is the breakdown of muscle protein.

In short, protein malnutrition causes a diminished immune response. Clonal expansion is not as great and the phagocytes are fewer. The response of individual cells may be lower secondary to decreased antibody production and intracellular depletion of enzymes. These deficits result in the clinical findings of increased numbers of infections and susceptibility to infection.

One Response to “Question: What happens to the immune system in protein malnutrition?”

  1. nixon 通販 Says:

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