Objective: To investigate the dynamic changes observed in serum levels of interleukins (ILs), tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) in severe acute respiratory syndrome (SARS).
Methods: Sixty-one cases of SARS were classified into the following categories according to the duration from the onset of illness to the time blood was drawn: 3-7 day group, 8-14 day group and over 14 day group. Forty-four healthy individuals served as the control. Serum levels of ILs, TNF-alpha and TGF-beta1 were measured in all cases. Serum antibodies to SARS-coronavirus (SARS-CoV) were measured only in SARS cases.
Results: The mean concentration of serum IL-6 in SARS patients did not differ from the control group in 3-7 day group and 8-14 day group, but became significantly higher in over 14 day group as compared to the control group, 3-7 day group and 8-14 day group (P < 0.01). The mean concentration of serum IL-8 in SARS patients did not differ from the control group in 3-7 day group, were significantly higher than the control group in 8-14 days group and in over 14 day group (P < 0.05) and significantly higher in over 14 day group than in 3-7 day group and 8-14 day group (P < 0.01). The mean concentration of IL-16 and TNF-alpha in all groups of SARS was higher than that of the control group, but it was the highest in over 14 day group (P < 0.01). SARS patients experienced higher concentration of serum IL-13 as compared to controls in 3-7 day group (P < 0.01), but it returned to normal levels in 8-14 day group and the over 14 day group. The mean concentration of serum IL-18 in SARS patients was significantly lower than that of the control group during all groups of SARS patients (P < 0.05); The mean concentration of TGF-beta1 in all groups of SARS patients was higher than that of the control group. Although TGF-beta1 in sera decreased in over 14 day group, the average was still higher than that of the control group (P < 0.01).
Conclusions: Proinflammatory cytokines and TGF-beta1 were elevated during the early phase of SARS, a phenomenon which may be associated with lung infiltration and proliferation. Concurrently, the mean concentration of serum IL-13 decreased gradually and the mean concentration of serum IL-18 level in SARS patients was lower than that of the control group during the whole disease course. It suggested that the immune state of SARS was obviously abnormal. Observing the dynamic changes in blood cytokine levels can provide us with a scientific basis to assess pathogenesis and efficacy of clinical treatment of SARS.