Different production of soluble HLA-G antigens by peripheral blood mononuclear cells in ulcerative colitis and Crohnʼs disease: A noninvasive diagnostic tool?

Abstract

HLA-G antigens are nonclassical major histocompatibility complex (MHC) class I molecules characterized by tolerogenic and antiinflammatory properties. Recently, a different expression of HLA-G antigens has been observed between intestinal biopsies of ulcerative colitis (UC) and Crohn's disease (CD) patients. These data suggested a functional role for HLA-G molecules in the diseases and proposed the HLA-G modulation as a marker for the diagnosis of UC and CD. The soluble HLA-G antigens (sHLA-G) are circulating molecules mainly produced by activated peripheral blood CD14+ monocytes. We tested, by specific enzyme-linked immunosorbent assay (ELISA), the sHLA-G molecule levels in the supernatants of unstimulated and bacterial lipopolysaccharide (LPS)-stimulated cultures of peripheral blood mononuclear cells (PBMC) from 30 healthy subjects, 10 CD, and 18 UC patients. The data were not influenced by treatment or disease activity. The results confirmed a different sHLA-G expression between the diseases, with a spontaneous secretion of sHLA-G in CD patients but not in UC and healthy subjects. Moreover, a lack of sHLA-G antigens has been reported in UC patient cultures after LPS activation but not in healthy subjects and CD patients. The defective sHLA-G production was related to an impaired IL-10 secretion in UC but not in CD. Overall, these results confirm the presence of a different biological characteristic between CD and UC patients and suggest sHLA-G production by PBMC as a noninvasive diagnostic tool in the early phases of the diseases.