Abstract • 74

Background: Hypogammaglobulinemia, such as XLA and CVID, is characterized by a high incidence of infections of the respiratory system and intestinal tract. An association between the number of infections and IgG plasma level has been described. Despite substitution therapy with immunoglobulins, recurrent (severe) bacterial infections are still observed.

Aim of the study: To compare clinical efficacy of intravenous immunoglobulin (IVIG) in high dose (adults: 600 mg/kg/4 wks; children: 800 mg/kg/4 wks) versus low dose (adults: 300 mg/kg/4 wks; children: 400 mg/kg/4 wks) during 2 periods of 9 months each.

Methods: Multi-center, double blind, randomized, cross-over study from November 1995 - February 1998.

Results: 43 patients entered the study (27 male, 16 female; 18 children, 25 adults; mean age 29,9 yrs); 41 patients completed the study. High dose IVIG results in a significant reduction of infections (p = 0.004) and a significant reduction in duration of infections (p = 0.015). Trough levels of total IgG and subclasses of IgG were higher during high dose IVIG treatment. In addition, trough levels of total IgG are significant positively related with antibody levels of several micro-organisms. With respect to number and type of side effects, the 2 dosages of IVIG are comparable.

Conclusions: High dose IVIG is correlated with a significant reduction of infections. In comparison to adults, infection rate in children shifted from severe to mild/moderate. Individual determinants such as diagnosis (XLA or CVID), age and the role of FcγR polymorphisms will be discussed.