PubMed · 431570
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L K Diamond. 1979-04-26. Red-cell suspensions.. https://pubmed.ncbi.nlm.nih.gov/431570/
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The measurement of cytokines produced by activated T cells refines assessment of cellular immune function and facilitates whole blood T cell assays. The latter approximate conditions in vivo and obviate the need to purify blood mononuclear cells. We have investigated the parameters of the whole blood assay in humans to standardize and optimize the detection of tetanus-specific T cell cytokine responses. Optimal conditions include the use of undiluted whole blood, an incubation time of 36-48 h and a minimum of delay between venesection and incubation of the blood with antigen. Blood should be drawn at a standard time of day to minimize inter-assay variation due to diurnal rhythmicity in cytokine production. Interferon-gamma or interleukin-2 are specific and reliable readouts; other cytokines can be measured to further characterize the TH1 and TH2 elements of the T cell responses, although tetanus-stimulated IL-4 production is detected in only a minority of healthy individuals. The whole blood assay is a potentially valuable tool for assessing cellular immune function and screening for antigen-reactive T cells in humans.
The original activated partial thromboplastin time-based assay for activated protein C (APC)-resistant factor Va (FVa) requires carefully prepared fresh plasma and cannot be used in patients receiving warfarin or in patients with antiphospholipid antibodies. A new test is described here that circumvents these limitations and distinguishes without overlap heterozygotes for APC-resistant FVa from persons with normal FV. A diluted test plasma is incubated with an FV-deficient substrate plasma and tissue factor and then clotted with Ca2+ or Ca2+ plus APC. Test results are independent of the FV level or the dilution of the test plasma used. Of 39 controls, 37 gave normal results. Two controls (5%) gave results indicative of APC resistant FVa and on DNA analysis were found to be heterozygous for FV R506Q. Twenty of 21 randomly selected patients receiving warfarin gave normal results. In the single patient with abnormal results, heterozygous FV R506Q was confirmed by DNA analysis. Two of 15 patients with protein S deficiency and 5 of 29 patients with a lupus anticoagulant had abnormal results. APC resistance caused by FV R506Q was confirmed in the five of these seven patients available for DNA analysis. APC-resistant FVa was also detected in 10 of 21 (46%) stored plasma from unrelated patients with venous thrombosis and negative earlier evaluation for a lupus anticoagulant or a deficiency of protein C, protein S, or antithrombin, which confirms a high incidence of this defect among patients with venous thrombosis.
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