Inter- and intra-individual variation in tests of cell-mediated immunity in young and old women.
ABSTRACT Exploring means to maintain or improve immunity in older persons has been receiving attention. To establish relationships between immune function and variables of interest, it is important to determine these variables accurately and precisely. Precision relates to the degree of variation in the laboratory test. The nature and magnitude of variability in tests of immune function has not been described extensively. We examined inter- and intra-individual variation in tests of cell-mediated immunity (CMI) in generally healthy and well-nourished young (20-40 years; n=15) and old (60-80 years; n=15) women. Subjects provided blood samples on 2 days within a week to determine leukocyte subsets, T-cell proliferation response to phytohemagglutinin A and concanavalin A, and interleukin (IL)-1beta, IL-2 and IL-6 production by stimulated mononuclear cells. Intra-individual variation was partitioned into day-to-day biological and analytical variation. Inter-individual variation was greater than intra-individual variability for most tests of CMI for both age groups. Furthermore, all CMI tests exhibited large day-to-day intra-individual variation (CV approximately 15% or greater) which was primarily due to biological rather than analytical sources, for both age groups. In conclusion, both age groups showed large between-person and considerable within-person variation in CMI tests. Therefore, assessment of CMI based on a single blood draw may not provide a reliable estimate of immune function.
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ABSTRACT: Day-to-day variability in biochemical indicators of iron status in well-hydrated and healthy women 70-79 y old (n = 10) was determined. Venous blood was collected on 4 nonconsecutive days during a 2-wk period. Analytical (sigma 2 rep) and biological (sigma 2 fd) variance components were computed based on a previously established scheme in younger adults. These two variance components were summed to obtain the total day-to-day variability (sigma 2 fd). Our results indicate that biological variation contributed most to the intraindividual variation. We calculated that sampling once for most iron indexes and twice for plasma transferrin receptors in elderly individuals is adequate to accurately determine these indexes whereas serum iron and transferrin saturation, indexes with high CVfd, require seven and eight measurements, respectively. These data, compared with previously published data in younger adults, demonstrate that aging is associated with a decreased variation in some indexes of iron status such as serum ferritin.American Journal of Clinical Nutrition 04/1993; 57(3):414-9. · 6.50 Impact Factor
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ABSTRACT: Polymorphonuclear functions are reported to be altered in aged humans. We have previously shown that chemotactic response, adherence, oxidative metabolism and Candida killing activity were abnormal in subjects over 70 years. These results lead us to investigate further the basic mechanisms of these alterations in a complementary series of elderly people over 75 years. However, we used in the present study the admission criteria of the SENIEUR protocol specially designed for immunogerontological investigations in humans. Neither the tests exploring the functions as a whole (migration and bacterial killing) nor those investigating the elementary components of these functions exhibited significant difference when compared to the sex-matched young controls. The discrepancy with our prior results is probably explained by the fact that the presently tested subjects had been selected according to more strict criteria. These data clearly demonstrate that neutrophils are intrinsically normal in the aged. Thus, it appears that the frequently observed neutrophil dysfunction in the elderly is due to the action of abnormal humoral components related to the aging process on otherwise normal neutrophils.Mechanisms of Ageing and Development 10/1986; 36(1):57-63. · 3.26 Impact Factor
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ABSTRACT: Nutrition is a critical determinant of immune responses and malnutrition the most common cause of immunodeficiency worldwide. Protein-energy malnutrition is associated with a significant impairment of cell-mediated immunity, phagocyte function, complement system, secretory immunoglobulin A antibody concentrations, and cytokine production. Deficiency of single nutrients also results in altered immune responses: this is observed even when the deficiency state is relatively mild. Of the micronutrients, zinc; selenium; iron; copper; vitamins A, C, E, and B-6; and folic acid have important influences on immune responses. Overnutrition and obesity also reduce immunity. Low-birth-weight infants have a prolonged impairment of cell-mediated immunity that can be partly restored by providing extra amounts of dietary zinc. In the elderly, impaired immunity can be enhanced by modest amounts of a combination of micronutrients. These findings have considerable practical and public health significance.American Journal of Clinical Nutrition 09/1997; 66(2):460S-463S. · 6.50 Impact Factor