intravenous immunoglobulin replacement therapy in the treatment of patients with common variable immunodeficiency disease an openlabel prospective study background common variable immunodeficiency cvid is characterized by humoral immunodeficiency resulting in increased susceptibility to infections and diminished responses to protein and polysaccharide vaccines intravenous immunoglobulins ivigs constitute a replacement therapeutic regimen for cvid and other primary and selected secondary immunodeficiencies but their mode of action is still not fully understoodobjective the purpose of this study was to assess the effect of ivig replacement therapy on the population of regulatory t cells cells expressing cd4 cd25 and low levels of cd127 tregs plasma levels of interleukin il2 and il10 and expression of fragment crystallizable receptor iib fc riib cd32b on cd19 b cells in cvid patientsmethods this was an openlabel prospective trial that included 17 cvid patients and seven healthy subjects as case controls the diagnosis of cvid was primarily established by clinical criteria designed by the european society for immunodeficiencies esid and was confirmed by low serum levels of two out of three subclasses of immunoglobulins igg iga or igm all cvid patients were treated with the ivig preparation flebogamma 5 a highly purified pasteurized normal human igg extracted from the serum of healthy individuals administered at a dose of 300mgkg by slow 2hour intravenous infusion blood samples were collected 30 minutes before the infusion and 30 minutes and 2 weeks after the termination of the infusion we examined i the plasma levels of il2 and il10 ii the percentage of cd4 t cells and tregs and iii the expression of fc riib on the surface of cd19 b cellsresults cvid patients had higher plasma levels of il2 p 0045 and il10 p 0002 as well as a higher expression of fc riib on cd19 b cells p 00119 before ivig compared with healthy controls the infusion of ivig led to further increases in the plasma levels of these cytokines 30 minutes after the termination of the infusion versus baseline il2 p 00004 il10 p 00003 ivig did not affect the expression of fc riib finally ivig infusion resulted in elevation of the percentages of cd4 t cells p0028 and tregs p 0006 in the blood 30 minutes after the infusionconclusion flebogamma 5 as replacement therapy not only supplies immunoglobulins but also modulates the immune response and in this way may provide additional benefits to patients with cvid