What is the function of T lymphocytes?

T lymphocytes (T cells) play vital roles in the adaptive immune response, specifically cell-mediated immunity, and are crucial in defending the body against infections caused by viruses, bacteria, fungi, and other pathogens. T cells also play a role in detecting and eliminating abnormal or cancerous cells.

There are different subsets of T lymphocytes, each with distinct functions:

1. Cytotoxic T cells (also known as killer T cells or CD8+ T cells):

- Function: Cytotoxic T cells identify and destroy infected cells, cancer cells, or cells with abnormal proteins on their surface. They release cytotoxic substances (such as perforin and granzymes) that create pores in the target cells, leading to cell death (apoptosis).

2. Helper T cells (CD4+ T cells):

- Function: Helper T cells are crucial in activating other immune cells. They recognize antigens presented on antigen-presenting cells (APCs) and release chemical signals (cytokines) to activate B cells, cytotoxic T cells, macrophages, and other immune cells necessary for an effective immune response.

3. Regulatory T cells (Treg cells):

- Function: Regulatory T cells play a critical role in maintaining immune tolerance and preventing autoimmune responses. They help suppress the activity of other immune cells, ensuring that the immune system does not attack the body's own tissues.

4. Memory T cells:

- Function: Memory T cells are long-lived T cells that form after an infection or vaccination. They remain in the body, "remembering" the specific pathogen. Upon re-exposure to the same pathogen, memory T cells can rapidly proliferate and mount a faster and more robust immune response.

Overall, T lymphocytes are essential components of the adaptive immune system, providing defense against pathogens and abnormal cells through cell-mediated immunity and immune regulation.