The invention provides a gene encoding a protein selected from among the following proteins (a) to (c): (a) a protein having any of the amino acid sequences of SEQ ID NOs: 2, 4, 6, 8, 10, 12, 14, 16, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, and 108; (b) a protein which has an amino acid sequence equivalent to any of the amino acid sequences of (a), except that one to several amino acid residues are deleted, substituted, or added, and which exhibits cytokine production regulatory activity; and (c) a protein which has an amino acid sequence having 90% or higher identity to any of the amino acid sequences of (a), and which exhibits cytokine production regulatory activity, as well as a gene useful for regulating cytokine production and use of the gene.