Both inflammatory and anti-inflammatory cytokines have been reported to be associated with acute graft-versus-host disease (aGVHD). However, their role and possible mutual interactions during aGVHD are not well understood. Eight patients with aGVHD and eight without who had undergone allogeneic HLA-identical peripheral blood stem cell transplantation were studied. The patients had no other complications known to affect serum concentration of cytokines, including infection. Serum concentrations of IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, TNF-α and IFN-γ were concurrently measured by a new technique, the cytometric bead array (CBA). We found that serum concentrations of IL-5, IL-6 and IL-10 were significantly higher in patients with aGVHD than in patients without it. By ratiometric analysis, the ratios of IL-5/IL-2, IL-5/IL-4, IL-6/IL-4 in patients with aGVHD were increased compared to the patients with no evidence of aGVHD. ROC analysis demonstrated that the ratio of IL-5/IL-4 was the most sensitive parameter associated with aGVHD. The second best marker of aGVHD was increased IL-5 concentration. Thus, our results indicate that the ratio of a particular cytokine/cytokine could be a potential diagnostic marker for aGVHD, more sensitive that the serum level of a given cytokine. This observation is consistent with a cross-talk among some cytokines and their possible interactions via respective receptors on cytokine-producing cells; these interactions may play an important role in pathogenesis of aGVHD. Further studies including a large number of patients and concurrent measurement of a variety of cytokines are needed to fully assess the diagnostic value of the cytokine ratiometric analysis. The CBA methodology provides a convenient and useful tool in such studies.

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