T-Cell Phenotypes in Children With Chronic Idiopathic Thrombocytopenic Purpura

Sir.—In their recent study on the T-cell subset distribution in the blood of children with acute or chronic idiopathic thrombocytopenic purpura (ITP), Dr Shannon et al1 found that the mean percentages of nonadherent mononuclear cells expressing OKT3, OKT4, and OKT8 membrane antigens did not differ from those calculated from the blood of control children. However, values for individual children with ITP varied widely and, in many instances, fell outside of the normal range irrespective of the age, type of ITP, or platelet count.We carried out a fluorescent microscopy analysis using a more complete panel of T-line monoclonal antibodies in five children with chronic ITP and, for comparison, in ten age- and sex-matched uninfected children with normal blood platelet count values. Whereas the proportions of OKT3-positive, OKT4-positive, OKT6-positive, OKT8-positive, and OKT9-positive cells were similar in the two groups, the children with chronic ITP had significantly higher percentages of