Increased interferon-gamma (IFN-gamma) levels produced in vitro by alloactivated T lymphocytes in systemic sclerosis and Raynaud's phenomenon

The aim of the present study was to analyse the in vitro proliferation and cytokine production by alloantigen-stimulated peripheral blood mononuclear cells (PBMC) obtained from patients affected by systemic sclerosis (SSc) an d patients with Raynaud's phenomenon (RP). In SSc patients the proliferatio n of PBMC stimulated in vitro with alloantigens was significantly increased compared with healthy subjects, while no differences were observed for RP patients. Lymphocytes from SSc patients also produced larger amounts of IFN -gamma compared with healthy controls. However, patients with clinically ac tive disease had lower IFN-gamma levels than those found in clinically stab le patients. Patients affected by RP showed significantly higher levels of IFN-gamma than healthy subjects. Analysis at the clonal level of the lympho cyte subsets involved in alloantigen stimulation in one patient affected by active SSc, and one subject with RP confirmed the results obtained using P BMC. In particular, in the RP patient but not in the SSc patient, we observ ed a population of CD4(+) T cells which proliferated to alloantigens in vit ro and produced high levels of IFN-gamma. We suggest that T lymphocytes pro ducing high levels of IFN-gamma might play a protective role in RP patients and in established scleroderma.