A double blind, placebo‐controlled, crossover therapy study with natural human IL‐2 (nhuIL‐2) in combination with regular intravenous gammaglobulin (IVIG) infusions in 10 patients with common variable immunodeficiency (CVID)

Summary Ten CVID patients with defective IL‐2 synthesis in vitro were treated with nhuIL‐2 in a placebo‐controlled, double blind, crossover therapy study during a period of 12 months. No severe side‐effects of nhuIL‐2 were recorded. Marginal serum nhuIL‐2 levels were measurable in individual patients only during the therapy phase. Serum levels of soluble IL‐2 receptors were unaffected by the therapy. nhuIL‐2 and placebo groups did not differ significantly with respect to requirement of IVIG substitutions which were performed whenever serum IgG levels dropped below 5 g/l: a total of 53 IVIG infusions (corresponding to 17.6 g IgG/month per patient) was necessary during the placebo phase, and 48 infusions (16‐4 g IgG/month per patient) during the nhuIL‐2 treatment phase. Thus, nhuIL‐2 therapy was ineffective in improving spontaneous IgG synthesis in vivo. Nevertheless, the group of patients receiving nhuIL‐2 during the first 6 months of the study exhibited a significant reduction of severe infections (n= 25) during the following 6 months of placebo treatment (n = 7) (P< 0–045). The infection score dropped in this group from 181 to 23 (P < 0015). Patients of the second group receiving first placebo and then nhuIL‐2 did not experience a significant difference in number and score of infectious episodes: 25 infections were recorded during the first 6 months and 24 during the following 6 months. We suppose that nhuIL‐2 therapy of CVID patients reduces susceptibility to severe infections, possibly via the induction of a specific antibody response, which is effective at the earliest 6 months after initiating nhuIL‐2 therapy.