Recombinant cytokines produced in Komagataella phaffii: advances in design, production, and purification strategies.

Cytokines are small glycosylated polypeptides that orchestrate immune responses and are widely produced in recombinant form for therapeutic and research purposes. This review highlights Komagataella phaffii as an efficient host for the heterologous expression of recombinant cytokines from human and other species. A systematic search of PubMed, Scopus, and Web of Science identified studies addressing upstream and downstream processes involved in cytokine expression. Molecular design strategies such as codon optimization, vector design, and signal peptide selection are discussed together with process parameters including temperature, inducer concentration, and bioreactor conditions, as well as recovery and purification of biologically active cytokines. Optimal production is often associated using multi-copy vectors driven by the AOX1 promoter, α-factor secretion signals, methanol induction (0.5-1.5% v/v), temperatures below 30 °C, and co-feeding strategies. Downstream purification commonly yields products exceeding 95% purity. Strategies such as PEGylation, albumin fusion, and antibody fusion are also described to improve cytokine stability and half-life. This review integrates and critically analyzes molecular and bioprocessing advances that establish K. phaffii as a powerful platform for recombinant cytokine production.