Lymphocyte response to mitogens in progressive systemic sclerosis

Lymphocyte responses to the mitogens phytohemagglutinin P (PHA‐P), concanavallin A (Con A), and pokeweed (PWM) were studied in 18 patients with progressive systemic sclerosis (PSS). A subgroup of these patients with multisystem involvement showed a significantly decreased lymphocyte response to both Con A and PWM when compared to normal controls. However those PSS patients with myositis, although having multisystem involvement, had normal lymphocyte response to all three mitogens. PHA‐P stimulation was normal in all PSS patients. Antinuclear antibodies, elevated sedimentation rates, and positive latex fixation were noted only in the multisystem disease group with abnormal lymphocyte function.