Thymic stromal lymphopoietin (TSLP) is a cytokine that plays a vital role in the immune system. It was first discovered in the thymus and is mainly produced by stromal cells. TSLP functions as a key mediator in initiating and regulating immune responses. It activates dendritic cells, which then stimulate the differentiation of T helper cells, especially Th2 cells. This leads to the release of various inflammatory cytokines, contributing to the development of allergic and inflammatory diseases. In addition, TSLP is involved in immune responses against certain pathogens. Its dysregulation has been associated with several immune - related disorders, making it an important target for therapeutic interventions in diseases like asthma and atopic dermatitis.