Decreased interleukin-7 and transforming growth factor-beta1 levels in blister fluids as compared to the respective serum levels in patients with bullous pemphigoid. Opposite behavior of TNF-alpha, interleukin-4 and interleukin-10.

This study analyzes both the blister fluid (BF) and serum levels of IL-7 and TGF-beta1 in samples from 18 patients affected with bullous pemphigoid (BP). These cytokines clearly present lower concentrations (P<0.001) in BFs than in the sera (1/20 and 1/2, respectively). In contrast, TNF-alpha, IL-10 and IL-4 present increased amounts in BFs that were 12, 12 and 17-fold, respectively. Eighteen sera (and 10 suction BF) from normal individuals were also employed as control. Normal sera presented significantly lower serum IL-7 concentrations than BP, while no significant TGF-beta1 variations were observed between normal and pathologic serum samples. In addition, the serum levels detected in BP patients were significantly correlated with disease intensity (r=0.64, P=0.003, evaluated as the number of blisters/erosions for each patient) as well as with the peripheral B-lymphocyte counts (r=0.80, P<0.001) and antibodies directed against the basement membrane zone (r=0.65, P<0.005). Although a clear explanation of this phenomenon is lacking, the data presented in this report agree with a strong decrease of IL-7 production at the local level (keratinocyte is known to produce IL-7 and the latter is known to be down-regulated by IL-10, and in other models also by TGF-beta1 and IL-4, whose levels are elevated in BP BFs) as opposed to an increased peripheral release of the same modulator. The IL-7 reduction may have a biological relevance in controlling a chronic, progressive disease.