This study investigates possible detrimental effects on the immune system of Inuit infants which may be induced by prenatal and postnatal (breast feeding) exposure to persistent environmental contaminants such as organochlorine compounds. These substances accumulate in the body of Inuit women in part due to their consumption of sea mammal fat and can be transferred to the foetus during pregnacy and to the infant during breast feeding. Immune system function will be evaluated using several parameters: 1) the level of antibody produced by the infant following Haemophilus influenza immunization; 2) the level of proteins which protect the infant against bacterial infections (complement system) before its immune system is fully developed; and 3) the level of chemical messengers (cytokines) which enable the various cells of the immune system to communicate with each other, thereby maintaining its proper function and assuring the protection of the infant against bacteria, parasitic and viral infections.
All immunological parameters are measured during the first 12 month of life. We evaluate also anti-Hib response. Given the crucial importance of the C' system in early infancy, we investigate C' abnormalities: the initial test will be the measurement of serum total hemolytic C' expressed in 50% hemolytic units (CH50). A normal CH50 generally indicates integrity of the C' system. In the event that low CH50 titers are observed, levels of C3 and C4 components are also carried out to determine from which of the alternative or the classical pathway originates the defect in the C' system. Th1 cytokines (IL-2, IFN and TNF) and Th2 cytokines (IL-4, IL-6 and IL-10) are measured in plasma collected at delivery in fetal blood as well as in infant blood at 6 month of age. Laboratory analyses Laboratory analyses for OCs and mercury as well as for vitamin A, will be performed at Quebec Toxicology Center which is located at CHUQ. This facility is the reference laboratory for human toxicology in the Province of Quebec. Their expertise in the determination of heavy metals and persistent organic pollutants in human fluids and tissues is recognized internationally. QA/QC program on heavy metals and OCs have been described previously. This laboratory participates in the QC program of NCP. Immunological parameters will be analyzed at the laboratory of histocompatibility and Immunology at CHUQ. This facility offers clinical and laboratory services required for investigations of autoimmune, immunodeficiency and allergic diseases.
QA/QC program of NCP
Québec Toxicology Center – CHUQ; McGill University; Wayne State University