2nd Annual BMRP Investigator Meeting - Abstract

Va24+ T-Cells are Deficient and Have Defective Interleukin-4 and Interferon-g Production in Inflammatory Bowel Disease

Randall H. Grose, Fiona M. Thompson and Adrian G. Cummins^a

Basil Hetzel Institute for Medical Research and The Queen Elizabeth Hospital (Woodville South, Australia)

Background: Va24+ T-cells represent a population of immunoregulatory NK T-cells that express both the CD161+ NK and CD3+ T-cell markers.  They are deficient in a number of human autoimmune diseases and in animal models of autoimmune disease.  The immunoregulatory Va24+ T-cell co-expresses the Vb11 chain of the ab T-cell receptor. Immunoregulatory Va24+ T-cells recognize a generic a-galactosylceramide antigen presented by CD1d molecules.  This may mimic membrane glycolipids exposed during intestinal damage.  They are distinguished functionally from classical T-cells by promptly producing cytokines including interleukin-4 (IL-4).

Aim: The aim of this study was to investigate any deficiency of Va24+ T-cells in inflammatory bowel disease.

Methods: Peripheral blood mononuclear cells were collected from subjects with Crohn’s disease (n=97), ulcerative colitis (n=66) and healthy controls (n=152).  Three-color flow cytometry was used to determine the surface markers.  A subset of subjects was analyzed by a-galactosylceramide/CD1d tetramers (tetramer+) to define the immunoregulatory population.  Mucosal intestinal biopsies were collected for Va24+ mRNA by relative PCR.  Another subset had blood mononuclear cells stimulated with anti-CD3/anti-CD28 antibodies and intracellular cytokine staining assessed by flow cytometry.
Results:  Circulating Va24+, Va24+ Vb11+ and tetramer+ Va24+ T-cells were reduced to 34% (p<0.001), 21% (p<0.001) and 0.6% (p<0.00001) in Crohn’s disease and were 86% (NS), 15% (p<0.001) and 6% (p<0.0001) in ulcerative colitis (UC), respectively of levels in control subjects.  Va24 mRNA expression in intestinal biopsies was reduced to 14% in Crohn’s disease and to 25% in UC.  Stimulated cytokine expression of  IL-4 and interferon-g (IFN-g) was markedly impaired in Va24+ and Va24+ tetramer+ T-cells in Crohn’s disease, but only in Va24+ tetramer+ T-cells in UC.

Conclusion: We conclude that Va24+ T-cells and immunoregulatory Va24+ tetramer+ T-cells are deficient in Crohn’s disease and Va24+ tetramer+ T-cells are deficient in UC.  Va24+ tetramer+ T-cells have defective cytokine production in both Crohn’s disease and in UC.
^aPrincipal Investigator