Fig. 2.

One SS patient contains partially neutralizing activity against interferon-α autoantibodies. PBMC were stimulated with interferon-α and interferon-γ in the absence and presence of serum. Phospho-STAT-1 monoclonal antibody followed by an anti-mouse-FITC secondary antibody was used for immunostaining. Each graph contains a red, blue, and green, line which represent cells unstimulated or stimulated by interferon-α, or interferon-γ, respectively. a HV control serum did not interfere with cell signaling by interferon-α and interferon-γ leading activation and phosphorylation of STAT-1. b In a thymoma patient serum, the presence of only anti-interferon-α autoantibodies block interferon-α binding therefore preventing phosphorylation. c SS patient #56, containing an intermediate level of serum anti-interferon-α autoantibodies can block some, but not all, interferon-α signaling activity leading to a partial block of phosphorylation