Browsing by Author "Scholvinck, Elisabeth Henriette"

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    The influence of age on the cellular immune response in patients with tuberculosis and healthy controls
    (Stellenbosch : Stellenbosch University, 2002) Scholvinck, Elisabeth Henriette; Beyers, Nulda; Beyers, A. D.; Levin, M.; Stellenbosch University. Faculty of Medicine & Health Sciences. Department of Paediatrics and Child Health.
    ENGLISH ABSTRACT: Children and adults may differ in their immune function. An adequate function of the individual's immune system is crucial to the risk for development of tuberculosis (TB) after infection with Mycobacterium tuberculosis (Mtb). Epidemiological evidence suggests an age-related incidence of TB. Furthermore, the prevailing clinical expression t ' of TB varies between age groups. -The aims of this study were to characterise the cellular immune response at different ages in TB patients and healthy individuals living in a region highly endemic for TB and to relate the findings to the clinical expression of TB in different age groups. A total of 150 persons of different ages were included in this study: 50 TB patients, (identified on the basis of clinical, radiological and microbiological characteristics), 49 healthy Mantoux positive (~15mm) and 51 healthy Mantoux negative (<15mm) subjects. All patients <12yrs were identified as having primary TB and postprimary TB was only diagnosed in patients ~12yrs. Haematologic indices were obtained from all the included subjects and found to be agerelated. With the exception of the absolute lymphocyte counts, all indices were significantly different in TB patients when compared to healthy controls. Whole blood was cultured and stimulated with PHA, PPD and ESAT -6 to measure lymphocyte proliferation and IFN-y, TNF-a, IL-2 and IL-10 production in the supernatants of the cultures. After stimulation with PHA, the production of IFN-y, TNF-a and IL-10 as well as lymphocyte proliferation were all age-related. After stimulation with PPD, age correlated positively with IFN-y production in healthy Mantoux positive subjects< 12yrs. In the age groups <20 yrs, patients produced similar amounts of IFN-y when compared to healthy age-related Mantoux positive controls. TNF-a and IL-2 production were not different between patients and controls. In this whole blood system, measuring any of these cytokines on their own did not differentiate patients from controls at all ages. The ratio of PPD stimulated IFN-y to TNF-a production was significantly less in patients with primary TB and postprimary TB when compared to Mantoux positive controls, irrespective of age. These findings indicate that calculated ratios between several cytokines may be useful markers of disease at all ages. ESA T -6 stimulated IFN -y production did not result in any significant correlation with age, but was significantly less in healthy Mantoux positive subjects ~12 yrs when compared to healthy Mantoux positive subjects <12 yrs and TB patients of all ages. This finding suggests that a positive immune response to ESAT -6 is indicative of recent immunological contact with Mtb. Total IgE was measured in serum. In children <12 yrs these values correlated with age and were highest in healthy Mantoux positive controls, thereby not confirming any inverse correlation between IgE and TB. Age should be recognised as a significant variable in quantitative measurements of cellular immune responses.