Polymorphonuclear neutrophil, monocyte, NK cell and macrophage represent cellular barrier of innate immunity and interferon is a cytokine barrier. Cytokines are small protein hormones produced by lymphocytes (helper T-cells), fibroblasts endothelial cells and antigenpresenting cells. The immune response requires complex interactions between different cells. The communication required for this is mediated by cytokines which act as chemical messengers of immune cells.