Since dehydroepiandrosterone sulfate (DHEAS) has been involved in the regulation of cellular immunity, the aim of the presence study was to evaluate whether the age-dependent reduction of DHEAS was associated with changes of natural killer (NK) immune function in healthy elderly subjects and in patients with senile dementia of the Alzheimer type (SDAT). Circulating DHEAS was determined throughout 24 h (circadian profile). NK cytotoxic activity was measured as spontaneous and induced cytotoxicity during exposure with DHEAS (10^–7 M), interleukin-2 (IL-2; 100 IU) and IL-2 (100 IU) coincubated with DHEAS (10^–7 M). DHEAS was significantly reduced in healthy elderly subjects (mesor M ± SD = 2.3 ± 0.5 µmol/l) and SDAT (1.6 ± 0.4 µmol/l) patients compared to healthy young subjects (6.7 ± 0.9 µmol/l; p < 0.001); significant differences were also found when healthy elderly subjects and SDAT patients were compared (p < 0.01). A significant inverse correlation between age and DHEAS levels was demonstrated in SDAT and healthy elderly subjects (p < 0.05). The decrease in 24-hour DHEAS secretion was associated with a higher NK cytotoxic response to DHEAS in the healthy elderly subject group than in healthy subjects of young age (p < 0.01). Increased NK cell activity during IL-2 incubation was found in patients with SDAT in comparison with the healthy elderly subject (p < 0.001). On the contrary, NK cell cytotoxic response of SDAT patients was less pronounced during DHEAS exposure and when DHEAS was coincubated with IL-2 (p < 0.001). These data suggest an immunomodulatory role of DHEAS on NK functional activity in physiological aging and SDAT. The antagonizing effect of DHEAS on NK overactivity during exposure with cytokines might counteract some neuroimmune components related to the pathogenesis and progression of the disease.

The use of specific IgE antibody determinations improves the clinical management of patients with allergy related symptoms in primary care, allowing advice to be given on specific allergen avoidance. However, the applicability of this diagnostic tool in different areas and countries should be further assessed in cost-effectiveness studies.

No abstract

Manufacturers should fully inform laboratories about a calibration change and its clinical impact. Laboratory reports for PSA measurements should indicate the assay's manufacturer and which calibration standard was used to avoid misleading information concerning PCa risk.

It is well known that the results of immunoassay methods can be affected by specific or non-specific interferences, ranging from 0.4% to 4.0%. The presence of interference may greatly compromise the accuracy of immunoassay analyses causing an error in the measurement, producing false-positive or false-negative results. From a clinical point of view, these analytical errors may have serious implications for patient care because they can cause misdiagnosis or inappropriate treatment. Unfortunately, it is a very difficult task to identify the irregular analytical errors related to immunoassay methods because they are not detectable by normal laboratory quality control procedures, are reproducible within the test system, may be clinically plausible and are relatively rare. The first line of defense against erroneous results is to use in laboratory practice only immunoassay systems with the highest level of robustness against interference. The second line of defense is always taking into account the possibility of interference in immunoassay results. A correct approach should be addressed on identification of samples at high risk of interference. The attainment of this goal requires a critical review of the test result in relation to patient's clinical conditions and literature data, taking into account the analytical characteristics of the immunoassay system. The experts in immunoassay systems should make every effort to find some specific and reliable quality indicators for irregular analytical errors in order to better detect and monitor erroneous immunoassay results due to specific or non-specific interferences.