Human IL-17A/F is a 40 kDa glycoprotein which is secreted as a disulfide-linked heterodimer. IL-17A/F consists of two proteins, IL-17A and IL17F. Human IL17A is produced as a 155 a.a precursor that includes a 23 amino acids signal sequence and a 132 amino acid chain that includes an N-linked glycosylation site. Human IL17F is produced as a 153 amino acid precursor with a 20 amino acid signal sequence and a 133 amino acid region and an N-linked glycosylation site. Both proteins (IL17A & IL17F) share 50 % amino acid sequence identity. Human IL17A & IL17F show approximately 60 % homology in their amino acid sequence to mouse IL-17A and IL-17F. Interleukin-17A/F and IL17A, IL17F homodimers are manufactured by activted CD4+ T cells, called Th17.