Abstract
Serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1alpha (IL-1alpha), and interferon-gamma (IFN-gamma) were estimated by conventional ELISA kits in 60, 42, and 58 Thai patients, respectively, with beta-thalassemia HbE and found to be above the normal range in 13%, 21%, and 33% of the patients, respectively. Using high-sensitivity ELISA systems, an additional 10 beta-thal/HbE patients were compared with 9 controls for concentrations of circulating TNF-alpha and IL-1beta , and 9 and 5 patients, respectively, but only 1 and none of the controls, respectively, showed values above the normal ranges. In patients with abnormally high IFN-gamma levels, basal hemoglobin values were significantly lower than in those with normal levels of the cytokine (mean +/- SEM: 6.03 +/- 0.24 vs. 7.08 +/- 0.18, p<0.05), although circulating concentrations of soluble transferrin receptors (sTrF) and absolute reticulocyte counts were similar in the two groups. Patients with raised or normal levels of TNF-alpha, IL-1alpha, or IL-1beta had similar basal hemoglobin values. In a phagocytosis assay, monocytes of patients with raised serum levels of IFN-gamma showed significantly more attached or ingested IgG-coated red cells than those of patients with normal concentrations of the cytokine (mean SEM: 192 +/- 22 vs. 140 +/- 14 per 100 monocytes, p<0.05). Moreover, in 3 of 4 of the former patients, the number of attached or ingested IgGcoated red cells per 100 monocytes was above the 95% reference limit for the latter patients. The results suggest that IFN-gamma aggravates the anemia of beta-thal/HbE by activating mononuclear phagocytes for destruction of red cells but not by inhibiting erythropoiesis. The elevated serum levels of TNF-alpha and IL-1 could contribute to complications of the disease, such as cachexia and thromboembolic phenomena.
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