A therapeutic composition is described that can be used for treating or prevention of diseases association with modulation of activity of human IL 1ß. In certain aspects the disclosed invention is based on engineering of a heterodimeric protein assembly that is capable of binding to human IL 1ß and attenuating its function. The heterodimeric protein assembly comprises an extracellular portions of human IL1 R1 and of human IL 1RAcP or their functional fragments. Each the IL1 R1 portion and the IL 1RAcP portion is fused to a distinct mutant of Fc portion of the human Ig Gamma 1. The two distinct Fc mutants in the heterodimeric protein assembly are engineered as to favor the heteromeric dimer formation between the two Fc mutants over any homomeric assembly. DNA expression vectors and expression systems for overproducing the polypeptides in mammalian cells are also provided for.