Cutaneous lymphocyte antigen expression on activated lymphocytes and its association with IL-12R (β1 and β2), IL-2Rα, and CXCR3

The majority of T lymphocytes that infiltrate psoriatic lesions express cutaneous lymphocyte antigen (CLA), a skin homing receptor involved in the influx of memory T cells to cutaneous sites. We investigated CLA expression on normal human peripheral blood mononuclear cells (PBMCs) and evaluated its association with IL-12 receptors, chemokine receptor, CXCR3, and IL-2Rα. PBMCs were stimulated in vitro with or without polyclonal activators (mitogen, or superantigens, or anti-CD3 + anti-CD28) in the presence or absence of exogenous rhIL-12. The percentage of CLA+ T lymphocytes increased significantly after superantigen stimulation compared to anti-CD3 + anti-CD28 or mitogen activation. The majority of activation induced CLA+ T lymphocytes co-expressed IL-12Rβ1, IL-12Rβ2, CXCR3, and CD25 in the presence of rhIL-12. Our results indicate that CLA expression on activated T lymphocytes is IL-12 and activation dependent and correlates with the expression of IL-12 receptors, IL-2Rα, and CXCR3. Monitoring the levels of Th1 differentiation markers such as CXCR3 and IL-12Rβ2 along with activation marker, CD25 on skin homing CLA+ T lymphocytes may provide insight into the mechanism of action of immunotherapies directed against Th1 type skin inflammatory diseases.