Several biomarkers featured in immune fingerprints associated with more than one type of peritonitis, suggesting a particularly useful role for the differential diagnosis of PD patients, namely HNE activity (HNEsubstr) and effluent levels of IFN-γ, TNF-α, IL-22, sIL-6R, MMP-8, CCL4, CCL11, CCL22, and CXCL10. This evidence concerns the gene CCL22 and peritonitis.