In summary, our engineered minimal IgV domain of PVR, presented as a Fc construct (vdPVR-Fc) binds tightly and equivalently to TIGIT, CD226 and CD96 (Kds in the low nM range), reduces the proliferation of T-cells and secretion of pro-inflammatory cytokines in-vitro, and attenuates the development of psoriasiform like symptoms in an in-vivo mouse model of psoriasis. The gene discussed is TIGIT; the disease is psoriasis.