IL27 A gene on chromosome 16p11 that encodes interleukin-27, a pro- and anti-inflammatory cytokine that regulates T-helper cell development, suppresses T-cell proliferation, stimulates cytotoxic T-cell activity, induces isotype switching in B-cells, and which has diverse effects on innate immune cells. Its target cells include CD4 T-helper cells, which can differentiate in types 1 and 2 effector cells (TH1 and TH2), and IL17-producing helper T-cells (TH17); it drives rapid clonal expansion of naïve CD4 T-cells. It strongly synergises with IL12 to trigger interferon-gamma production by naïve CD4 T-cells and binds to the cytokine receptor WSX-1/TCCR, which appears to be required for IL27-mediated signal transduction. IL27 potentiates the early phase of TH1 response and suppresses TH2 and TH17 differentiation. It also has antitumour and antiangiogenic activity, with activation of production of antiangiogenic chemokines such as IP-10/CXCL10 and MIG/CXCL9. IL27 is also a less preferred gene symbol for what is now designated as IL17D, see there.