Patent ID: 7619066

Claim:
A method of reducing aggregation of an aggregating interleukin-1 receptor antagonist (IL-1ra) comprising making a variant of an IL-1ra comprising the amino acid sequence set forth in SEQ ID NO: 3, wherein the variant comprises an amino acid sequence that is at least 95% identical to the amino acid sequence set forth in SEQ ID NO: 3; wherein: a) the variant has an amino acid that does not have a charge at the position corresponding to Lysine-93 of SEQ ID NO: 3; b) the variant has an amino acid that does not have a charge at the position corresponding to Arginine-97 of SEQ ID NO: 3; or c) the variant has an amino acid that does not have a charge at the position corresponding to Lysine-93 of SEQ ID NO: 3 and an amino acid that does not have a charge at the position corresponding to Arginine-97 of SEQ ID NO: 3; and wherein if the variant has an arginine at the position corresponding to Arginine-97 of SEQ ID NO: 3, the variant does not have a threonine or a histidine at the position corresponding to Lysine-93 of SEQ ID NO: 3; thereby producing an IL-1ra having reduced aggregation.