TH1 refers to the TH1 type of immune response, which may also be called the TH1 cell major helper (cellular) immune response.TH refers to helper T cells, which include TH1, TH2, TH17, and regulatory T cells. TH1 cells recognize antigens presented by major histocompatibility complex class I or class II molecules.TH1 cells play an important role in recognizing and clearing intracellular pathogens such as viruses and bacteria, including Mycobacterium tuberculosis, Mycobacterium leprae, and Leishmania protozoa.TH1 cells contribute to the activation of macrophages to fight against these pathogens and to disrupt their evasive strategies. TH1 cells are helper T cells that produce immune responses that are all cytokine-mediated. For more medical knowledge it is recommended to consult a specialist.