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Construct a table to identify THREE types of T-lymphocytes, and outline the role of each type in the immune response. - HSC - SSCE Biology - Question 22 - 2009 - Paper 1
Question 22
Construct a table to identify THREE types of T-lymphocytes, and outline the role of each type in the immune response.
Worked Solution & Example Answer:Construct a table to identify THREE types of T-lymphocytes, and outline the role of each type in the immune response. - HSC - SSCE Biology - Question 22 - 2009 - Paper 1
Step 1
Type 1: Helper T-Lymphocytes (CD4+ T-cells)
Answer
Helper T-lymphocytes play a crucial role in the immune response by activating and regulating other immune cells, including B-cells and Cytotoxic T-cells. They secrete cytokines that stimulate B-cells to produce antibodies and enhance the activity of macrophages, making them vital for adaptive immunity.
Step 2
Type 2: Cytotoxic T-Lymphocytes (CD8+ T-cells)
Answer
Cytotoxic T-lymphocytes are responsible for directly killing infected or cancerous cells. They recognize specific antigens presented by major histocompatibility complex (MHC) class I molecules on infected cells and initiate apoptosis (programmed cell death) to eliminate these threats.
Step 3
Type 3: Regulatory T-Lymphocytes (Tregs)
Answer
Regulatory T-lymphocytes help maintain immune homeostasis by suppressing excessive immune responses and preventing autoimmunity. They ensure that the immune system does not attack the body's own tissues, thereby playing a crucial role in maintaining tolerance.