Antigen-specific CD4-positive T cell (CD4+ T cell) (CD4+ T cell)

Antigen-specific CD4-positive T cells, commonly known as helper T cells, are a fundamental subset of lymphocytes essential for the coordination of the adaptive immune response (Janeway et al., 2017). These cells are characterized by the expression of the CD4 co-receptor, which enables them to recognize specific peptide antigens presented by Major Histocompatibility Complex class II (MHC II) molecules on professional antigen-presenting cells (StatPearls, 2024). Upon encountering their cognate antigen, these cells undergo clonal expansion and differentiate into various functional subsets, such as Th1, Th2, Th17, and regulatory T cells (Tregs), each defined by a unique cytokine profile that directs the activity of B cells, CD8+ T cells, and innate immune cells (NIH, 2023). In clinical contexts, these cells are primary targets for immunomodulation; for instance, they are suppressed in organ transplantation and autoimmune diseases to prevent tissue damage, while in oncology and vaccinology, strategies aim to enhance their activation to mount effective anti-tumor or anti-pathogen responses (PubMed, 2022). Dysregulation of antigen-specific CD4+ T cells is a hallmark of numerous conditions, including rheumatoid arthritis, multiple sclerosis, and HIV/AIDS, where the loss of these cells leads to profound immunodeficiency (Nature Reviews Immunology, 2021).

Other names

Helper T cellsTh cellsCD4+ T lymphocytesAntigen-specific helper T cells

Modulation of T-cell receptor signaling, inhibition of costimulatory pathways (e.g., CD80/86 blockade), calcineurin inhibition, and immune checkpoint blockade (PD-1/CTLA-4).