SP (Single Positive) T cells

Single Positive (SP) T cells are a type of immune cell that mature in the thymus, a small organ in the body. They have a specific marker called CD4 or CD8. CD4+ T cells (helper cells) assist in coordinating immune responses, while CD8+ T cells (killer cells) directly attack infected or abnormal cells. SP T cells have only one of these markers, indicating their specialized role. They develop through a selection process to ensure they recognize threats properly without harming the body’s own tissues. Once mature, they circulate in the bloodstream and lymphatic system, ready to defend against infections or cancer.