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Tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and granulocyte monocyte-colony stimulating factor (GM-CSF) were measured in serum and involved and uninvolved skin blister fluids of 20 psoriatic patients and 10 healthy subjects, by enzyme immunoassay. TNF-alpha and IL-6 were always detectable in involved skin blister fluids, while GM-CSF was detected only in 45% of these samples. TNF-alpha, IL-6 and GM-CSF were detected in 95, 100 and 10% of uninvolved skin blister fluid samples, respectively. TNF-alpha and IL-6 were found in 50 and 30% of control blister fluids, while GM-CSF was never detected. In serum, TNF-alpha was detected in 75% of patients and in 70% of controls; IL-6 in 45% of patients and in no controls; and GM-CSF in 35% of patients and in 20% of the controls. The median TNF-alpha and IL-6 levels in involved skin were statistically higher than those of both uninvolved and control skin blister fluids. TNF-alpha and IL-6 levels in blister fluids obtained from both involved and uninvolved skin were higher than those of the patients' sera. GM-CSF, when present in involved skin blister fluids, showed correlated levels with the other cytokines (TNF-alpha: R = 0.85, P = 0.004; IL-6: R = 0.72, P = 0.03). TNF-alpha was highly correlated with IL-6 (R = 0.78, P < 0.00001) in involved skin blister fluids. TNF-alpha and IL-6 levels of involved skin blister fluids showed significant correlations with the psoriasis area and severity index scores in the patients, suggesting a direct relationship between these cytokines and the clinical manifestations of the disease. Moreover, the TNF-alpha levels were particularly related to the erythema scores in the patients, further supporting evidence of their role in the pathogenesis of the disease.
Bonifati et al. (Thu,) studied this question.