THE CLINICAL OUTCOME OF AUTOIMMUNE THROMBOCYTOPENIC PURPURA PATIENTS IS RELATED TO THEIR T-CELL IMMUNODEFICIENCY

In this work we have furthered the understanding of the alterations of T lymphocytes from 29 patients with active autoimmune thrombocytopeni c purpura (ATP) and the clinical significance of their lymphocytes. An increased percentage of in vivo activated (CD25+ and DR+) T lymphocyt es was found in ATP patients with respect to that found in 22 healthy controls. The function of these T cells measured as the proliferative response to polyclonal mitogenic signals is heterogeneously impaired i n ATP patients. T lymphocytes from 65-5% (19/29) of the ATP patients s howed a decreased proliferative response to these mitogenic signals. T his functional alteration is associated with a redistribution of the T cell compartment in these patients' peripheral blood since a signific ant decrease of CD4+ T lymphocytes was found. We have also found that the impairment of the T cell function is different in the diverse clin ical situations of the disease. Those with stable, untreated disease s howed a marked decrease in the T cell proliferative response to mitoge ns. Furthermore, those patients who did not respond either to steroids or to splenectomy showed significantly reduced T lymphocyte blastogen esis after phytohaemagglutinin (PHA) stimulation in comparison to that found in responding patients.