Involvement of β2-microglobulin in CD69 expression on T cells

beta (2)-Microglobulin (beta M-2) is the light chain of the class I HLA molecule. The serum level of beta M-2 is elevated in various diseases including lymphoma, inflammation, viral infections and chronic renal dysfunction. The present study addressed the possible influence of beta M-2 on T lymphocyte activation in vitro. Peripheral blood mononuclear cells from a group of 17 healthy subjects were examined. Stimulation with OKT3 and fibronectin in combination with 30 mg beta M-2/dl resulted in a two-fold increase of cell proliferation. A similar effect was observed when OKT3 and collagen I were applied as well as when OKT3 and collagen IV were used as costimulation to T cells. The CD69 expression, measured by flow cytometry was significantly enhanced above the control level (1.52 +/- 1.03% vs 33.21 +/- 20.26%, p <0.01, control group and 30 mg beta M-2/dl, respectively). Together, these observations suggest that beta M-2 may play a role in modulating lymphocyte proliferation, possibly through modification of the CD69 molecule.