Previously unreported CD8+CD28− and CD8+CD28+ T-cell subsets occur in healthy individuals and expand in patients suffering from autoimmune disease. Here we studied, for the first time, the expression of CD8+CD28+, CD8+CD28−, and CD8+CD56+ subpopulations in induced sputum from asthmatics. Using sputum samples, purified CD8+ T cells were stained for surface antigen CD28, CD56, FITC-conjugated anti-perforin, and anti-IFN-γ. Cytotoxic activity was evaluated in a chromium releasing test. Induced sputum CD8+CD28− T cells were found to be more expanded and expressed low levels of IFN-γ in severe asthmatics than mild asthma and age-matched healthy controls. The predominance of CD8+CD28− T cells can be in part explained by the expansion of CD8+CD56+. CD8+CD28− T cells from severe asthmatics produced high intracytoplasmic perforin and exerted a potent cytotoxic activity. Considering their phenotyping and functional properties, the CD8+CD28− T-cell subset may constitute an intermediate phenotype in the process of CD8+ T-cell differentiation of effector-type cells in severe asthmatics. Functional studies showed that CD8+CD28− T cells had cytotoxic function.
Plasma homocysteine was assessed in Behcet's disease (BD) patients in order to determine the prevalence of hyperhomocysteinaemia in BD and to test its association with clinical manifestations of the disease. The study included 59 patients with BD and 118 age- and sex-matched healthy subjects. Plasma homocysteine, vitamin B(12) and folate were assessed by automated immunoassay methods. Hyperhomo-cysteinaemia was defined as plasma homocysteine >15 micromol/l. Plasma homocysteine concentrations and the prevalence of hyperhomocysteinaemia were significantly higher in BD patients than in controls [median (5th-95th percentile), 11.3 (6.6-28.1) vs. 10.6 (6.6-17.1) micromol/l, and 25.4% vs. 9.3%, respectively]. In BD patients, hyperhomocysteinaemia was related to male gender, disease severity and uveitis [odds ratio (OR), 5.32; 95% confidence interval (CI), 1.43-21.61; p = 0.008], but not to age, smoking, disease activity, deep venous thrombosis, arthritis or neurological involvement. The association between uveitis and hyperhomocysteinaemia persisted (multi-adjusted OR, 7.46; 95% CI, 1.03-54.3; p = 0.05) after adjusting for gender, age, disease activity and duration, smoking, deep venous thrombosis, and serum concentrations of creatinine, vitamin B(12) and folate. Plasma homocysteine should be measured in patients with BD, and the effect of B-vitamin supplementation should be tested in those with hyperhomo-cysteinaemia.
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