What are the functions of each subset of CD4 T cells?

CD4 T cells can be broadly classified into 5 subsets based on their specific functions: 

• Th1 cells: Th1 cells are a group of pro-inflammatory cytokines that play a crucial role in cell-mediated immunity. They activate macrophages to combat intracellular pathogens, such as viruses and certain bacteria and support the development of cytotoxic T cells that can directly kill infected cells. 
• Th2 cells: Th2 cells are a group of anti-inflammatory cytokines that are involved in humoral immunity. They play a key role in the production of antibodies by B cells and in activating other cells such as eosinophils that work to eliminate extracellular pathogens during allergic responses and parasitic infections. 
• Th17 cells: Th17 cells are involved in producing interleukin-17 (IL-17), a signaling molecule that stimulates other immune cells. They are primarily responsible for maintaining mucosal barriers and contributing to clearance of pathogens at mucosal surfaces. 
• Treg cells (Regulatory T cells): Treg cells play a critical role in maintaining homeostasis and self-tolerance by monitoring immune tolerance and suppressing excessive immune responses to self-antigens and preventing autoimmunity. 
• Tfh cells (Follicular Helper T cells): Tfh cells play a specialized role in providing assistance to B cells. They are crucial for the formation of germinal centers, the maturation of antibodies with high affinity, and the development of memory B cells.