Zinc and immunocompetence in protein-energy malnutrition

Malnourished children have thymic atrophy which is reversed by zinc supplementation. To see if their defect in cell-mediated immunity was also associated with zinc deficiency ten children were skin-tested with Candida antigen on both arms. One test site was covered with local zinc sulphate and the other with placebo ointment. There was a highly significant increase in the typical delayed-hypersensitivity reaction at the site covered with zinc. The magnitude of the difference between the supplemented and unsupplemented arms correlated negatively with the plasma-zinc concentration. These data show that zinc deficiency is a cause of the immunoincompetence seen in malnutrition. The normal reactions of the zinc-supplemented side indicate that, of the many nutritional deficits of malnourished children, zinc deficiency specifically impairs the cell-mediated immune system. Local skin-testing with and without zinc may provide a measure of zinc status. Local application of zinc may enhanc the reliability of tests to diagnose diseases such as tuberculosis in malnourished patients.(AU)

Immunologic diagnosis of schistosomiasis. III. The effects of nutritional status and infection intensity on intradermal test results in St. Lucian children

The question of the insensitivity of immediate and delayed skin testing in children was studied with respect to both nutritional status and intensity of infection. Ninety-seven children on the island of St. Lucia, 5 to 11 years of age, with almost equal male:female distribution, all excreting eggs of Schistosoma mansoni were tested as follows: qualitatively and quantitative stool examinations; anthropometric measurements (height, weight, mid-arm circumference and triceps skinfold thickness); hematocrit; fluorescent antibody test; and skin tests with control material, S. mansoni adult worm antigen (both Puerto Rican and St. Lucian strains), and intermediate strenght PPD tuberculin. The anthropometric measurements revealed marginal malnutrition among the children. The overall positive intradermal response rate for each of the two antigens was similar, being 56 percent for the immediate and 37 percent for the delayed test. There was no relationship discernible between relative over- and under-nutrition and the skin test responses. A striking and highly significant positive association was revealed, however, between the intensity of infection, as shown by quantitative egg counts, and the sensitivity and extent of both the immediate and delayed skin test reactions.(AU)

Immunologic diagnosis of schistosomiasis. II. Further studies on the sensitivity and specificity of delayed intradermal reactions

The specificity of the delayed intradermal reaction was compared to that of the immediate response in 80 adult St. Lucians with proven schistosomiasis mansoni, using homologous and heterologous antigens. Adult worm antigens at a uniform concentration of 35æg/ml from four geographic strains of Schistosoma mansoni (St. Lucian, Puerto Rican, Brazilian, and Egyptian) and from S. haematobium and S. japonicum were color coded and injected randomly in the skin of the upper back. The immediate reactions to all the antigens showed equal sensitivity (94 to 99 percent positive). The delayed reactions with the four S. mansoni strains ranged from 49 to 60 percent positively, but the heterologous S. haematobium and S. japonicum antigens were significantly less sensitive, with only 20 percent and 30 percent positive reactions. In an attempt to improve the sensitivity of the delayed intradermal test, 30 of the 80 St. Lucians were retested 1 month later with different concentrations of the Puerto Rican antigen (5, 15, 35, 70 æg/ml). Immediate rections were 100 percent at all but the lowest concentration (93 percent). Delayed reactions were at their peak (87 percent) at the standard concentration of antigen (35 æg/ml), the other concentrations being similar with the exception of the lowest (53 percent). Comparisons of the results of the two series of tests performed 1 month apart in the same individuals revealed no changes in the immediate reactions, but a marked increase in both the percentage positivity and the mean lesion area in the delayed response.(AU)

Immunologic diagnosis of Schistosomiasis. I. A controlled study of intradermal (immediate and delayed) and serological tests in St. Lucians with Schistosoma mansoni and in uninfected St. Vincentians

In order to test the efficacy of antibody-mediated immunologic methods for the diagnosis of schistosomiasis (immediate intradermal and serological tests) and to compare them with a cell-mediated immunologic reaction (the delayed intradermal test), 350 subjects were examined. Approximately half of them were from the West Indian island of St. Lucia, all with proven schistosomiasis mansoni on fecal examination, and the other half were comparable subjects from St. Vincent, an island 30 miles distant where schistosomiasis has never been found. Five different antigens utilized in the intradermal tests (prepared from Schistosoma mansoni cercariae, adult worms and eggs, and from S. haematobium and S. japonicum eggs) were injected blindly in a randomized manner. The antigens were almost equally and highly sensitive in the immediate skin reaction in the adult St. Lucians (89-95 percent, with the exception of S. haematobium, 74 percent), but were far less sensitive in the children. There was a large number of false positive immediate responses among the Vincentians, e.g., 44 of 171 subjects tested with the S. mansoni cercarial antigen. Delayed skin reactions, which among the St. Lucians reached a peak of 66 percent positively with S. mansoni adult worm antigen, were less sensitive than the immediate reactions, but appeared to be more specific. Among the antigens (S. haematobium and S. japonicum eggs), while the Vincentians had very few false positive reactions with the homologous and none with the heterologous antigens. Of the three serologic tests (complement fixation, cholesterol-lecithin flocculation, and flourescent antibody), the first two were insensitive and non-specific; the third was the only one that provided results which were at all acceptable.(AU)

Immunological studies in Schistosoma mansoni infection in St. Lucia

An investigation was made of the immunological status of matched groups of patients with Schictosoma mansoni infection in St. Lucia, one group with hepatosplenic disease and the other with only intestinal disease. No impairment of humoral or cellular immunity was detected in either group. IgG and IgM levels were above normal range and were higher in the patients with intestinal disease, but only the difference between groups in IgG level was statistically significant. In their reaction to specific schistisome antigens and ability to develop delayed hypersensitivity, the groups were about equal. (AU)