Question

How do killer T cells work?

Answer 1

T lymphocytes are a kind of lymphocyte. T cells are one of the immune system's most essential white blood cells, and they play a key part in the adaptive immune response. The presence of a T-cell receptor (TCR) on the surface of T cells distinguishes them from other lymphocytes. Hematopoietic stem cells in the bone marrow give rise to T lymphocytes. Regulatory T cells are a subset of T cells that play an important role in tolerance by allowing immune cells to distinguish between invading cells and "self" cells.

Complete answer:
The activation of helper T cells is a multistep process that starts with antigen-presenting cells like macrophages. Infectious agents or foreign particles are ingested by these cells, which partially breakdown them and then export parts of them to the cell surface as antigens. The particles are seen beside class II MHC molecules there. The MHC-antigen complex is then binded to a receptor on the surface of the helper T cell. Helper T cells are activated in the next step in one of two ways: by cytokine stimulation or by a costimulatory reaction between a signaling protein called $B7$, which is found on the antigen-presenting cell's surface, and the $CD28$ receptor protein, which is found on the helper T cell's surface. When helper T cells are activated, the number of helper T cells that recognize a given antigen increases, as does the production of numerous T-cell cytokines.

Note:
T cell deficit is a T cell deficiency produced by diminished function of individual T cells, resulting in a cell-mediated immune immunodeficiency. T cells are one of the two basic types of lymphocytes, and their major role is to aid in the human body's immunity (the other being B cells).
T Hereditary diseases include severe combined immunodeficiency (SCID), Omenn syndrome, and cartilage–hair hypoplasia can cause complete T cell insufficiency. Low T cell counts frequently signal immune system or lymph node issues. Low T cell numbers can be caused by a variety of factors, including viral illnesses such as influenza and age.