CD4 and Keratoconjunctivitis sicca: In Sjögren’s syndrome, the lacrimal glands are infiltrated by immune cells, including CD4+ helper T cells, CD8+ cytotoxic T cells, B cells, plasma cells, macrophages, dendritic cells, and mast cells, leading to reduced tear production and dry eyes, a condition referred to as Sjögren’s syndrome keratoconjunctivitis sicca (SS-KCS) [9].