The present invention relates to improved binding proteins, for use as a medicament, in particular for the prevention or treatment of autoimmune and inflammatory disorders, for example allergic asthma and inflammatory bowel diseases. The invention more specifically relates to a soluble protein, comprising a complex of two heterodimers, wherein each heterodimer essentially consists of: (i) a first single chain polypeptide comprising: (a) an antibody heavy chain sequence having VH, CH1, CH2, and CH3 regions; and (b) a monovalent region of a mammalian binding molecule fused to the VH region; and (ii) a second single chain polypeptide comprising: (c) an antibody light chain sequence having a VL and CL region; and (d) a monovalent region of a mammalian binding molecule fused to the VL region; characterised in that each pair of VH and VL CDR sequences has specificity for an antigen, such that the total valency of said soluble protein is six. The invention further relates to soluble SIRPa-binding antibody-like proteins as shown in FIG. 1.