Immunological studies of children with anaphylactoid purpura.

Anaphylactoid purpura is a small-vessel, vasculitic disease of unknown etiology, but it is thought to be caused by an immunoglobulin-mediated inflammatory process. To study the immunological profiles of local anaphylactoid purpura patients, during the period from October 1996 to October 1997 with 17 patients, (6 boys and 11 girls), (aged 3 years to 17 years, mean age: 7.9 years), with anaphylactoid purpura who visited National Taiwan University Hospital. Immunological studies were performed in 17 patients and 20 age-matched healthy controls. Higher C3 was noted in patients (126.2 +/- 26.7 mg/dL) than in the control group (116.1 +/- 16.7 mg/dL), although without statistical significance (P = 0.307). C4 levels of patients were significantly higher in patients than control group (38.6 +/- 13.4 v.s. 23.7 +/- 6.9 mg/dL), P < 0.001). There were no significant differences in the IgG and IgM levels between patient and control groups. In contrast, the IgA levels of patient were significantly higher than that control groups (293.1 +/- 102.9 v.s. 179.8 +/- 71.0 mg/dL, P = 0.001). The serum level of TGF-beta 1 of patients was higher than that of the control group although not statistically significant (44.1 +/- 27.3 v.s. 29.9 +/- 19.0 ng/mL, p = 0.067). A significantly higher percentage of T cells was noted in anaphylactoid purpura patients than controls (71.5 +/- 9.2% v.s. 65.0 +/- 6.3%, P = 0.016). However, no significant difference was found in other subpopulations of lymphocytes. These basic immunological profiles may be helpful for further work on the pathogenesis of anaphylactoid purpura.