Cell-mediated immunity and immunoglobulin levels in light-for-date infants.

Cell-mediated immune response and circulating levels of immunoglobulins were studied in 75 full-term newborn babies. The results showed that though the immunoglobulin levels were not altered, cell-mediated immunity was significantly depressed in infants with birth weight less than 2 500 g and this may result in lowered resistance of infection.

Antimicrobial factors in human milk.

Levels of immunoglobulins, lactoferrin and lysozyme were determined in milk samples obtained from well-nourished and under-nourished Indian women at different stages of lactation. The concentration of immunoglobulins and lactoferrin was higher in colostrum than in mature milk while the lysozyme levels showed a progressive increase with the period of lactation. There were no significant differences in the levels between the two groups of women. Administration of iron did not alter either the total or percentage saturation of lactoferrin in milk. These results indicate that antibacterial factors in milk are not influenced by the nutritional status of the mother and that iron supplementation does not interfere with the bacteriostatic function of lactoferrin.

PIP: Lower incidences of infection among breastfed vs. bottlefed infants have been attributed, not only to bottle contamination, but to the presence of various antibacterial factors in breast milk. 3 of these factors, immunoglobulins, lysozyme, and lactoferrin, were quantitated from milk samples from well-nourished and under-nourished Indian women in various stages of lactation. An ancillary concern of this study was to determine whether iron supplementation in under-nourished lactating women might abolish the bacteriostatic mechanism of lactoferrin by altering its saturation in milk, thus interfering with its biological function. 250 women gave breast milk samples for study. In addition, 11 lactating women were given 200 mg of iron intramuscularly, and their milk samples were assayed. In the nonsupplemented women, the concentration of immunoglobulin A (IgA) was high in colostrum, with a mean level of 350 mg/100 ml, and fell rapidly during the first 4 weeks of lactation, to a mean level of 110 mg/100 ml. IgG concentration was slightly higher in colostrum than in mature milk. Lactoferrin concentration was very high in colostrum, with a mean level of 600 mg/100 ml, and fell progressively up to 5 months of lactation, stabilizing at a mean level of 180 mg/100 ml. Lysozyme content of colostrum was lower than that of mature milk and showed a progressive increase with duration of lactation; its highest level of 42 mg/100 ml was reached at 12 months. No significant differences in levels of immunoglobulins, lactoferrin, and lysozyme were found between well-nourished and under-nourished mothers. In women who received the iron supplements, at first the mean level of total lactoferrin was 240 mg/100 ml, 9% of which was saturated. No significant changes in concentrations of either total or saturated lactoferrin were found after administering the iron supplement.

Secretory IgA in protein-calorie malnutrition.

The secretory IgA system was investigated in children with protein-calorie malnutrition (PCM). The results of the study indicated that in children suffering from kwashiorkor and marasmus the concentration of IgA in duodenal fluid, saliva, nasal secretions, and tears was significantly reduced on admission and returned to normal 4 weeks after treatment. However, the concentration of secretory IgA in children with mild to moderate PCM was similar to that of normal children. Secretory IgA deficiency may be an important factor in promoting bacterial growth and this may account for the increased incidence and severity of mucosal infections in children with severe PCM.

Anaemia and immune response.

Nutritional anaemia is a major public-health problem in many parts of the world, and iron deficiency appears to be the most important cause. The immune response is believed to be impaired in anaemia. The results of the present study, carried out in young children, indicate that both the cell-mediated immune response and the bactericidal activity of leucocytes are impaired when levels of haemoglobin fall to 10 g/dl or less.

Functional significance of growth retardation in malnutrition.

Various functional parameters involved in resistance to infection were investigated in children suffering from varying grades of protein-calorie malnutrition. It was observed that the phagocytic function was impaired in children whose weights were below 80% of the Indian Council of Medical Research standard, whereas the cell-mediated immune response was altered in those with weights below 70% of the standard. Antibody response to typhoid antigen was impaired in children with severe protein-calorie malnutrition, while the response to diphtheria and tetanus toxoids was normal in all. These observations suggest that malnourished children whose weights are below 80% of the Indian standard are likely to suffer from at least one functional handicap which may increase the risk of infection. In any action-oriented program, priority should, therefore, be given to this group of children.