Question

Which of the following statements about antibodies is true? a. They are produced by helper T cells. b. They are produced by killer T cells. c. They are produced by B cells. d. all of the above

Short answer

c. They are produced by B cells.

Step-by-step solution

Understanding Antibodies

Antibodies, also known as immunoglobulins, are proteins produced by the immune system to help fight infections. They specifically target and neutralize foreign objects like bacteria and viruses.

Role of Helper T Cells

Helper T cells, a type of immune cell, do not produce antibodies. Instead, they activate other immune cells, including B cells, and help regulate immune responses.

Role of Killer T Cells

Killer T cells (Cytotoxic T cells) are responsible for destroying infected cells in the body but do not produce antibodies. They recognize and kill cells that are infected by viruses.

Role of B Cells

B cells are the only type of immune cells that produce antibodies. When activated, B cells mature into plasma cells which directly secrete antibodies into the bloodstream.

Evaluating the Statements

a. Incorrect - Helper T cells do not produce antibodies. b. Incorrect - Killer T cells do not produce antibodies. c. Correct - B cells produce antibodies. d. Incorrect - Not all of the cells listed produce antibodies.

Key concepts

role of B cells

B cells play a crucial role in the adaptive immune system. They are a type of white blood cell known as lymphocytes. Their main function is to produce antibodies against antigens.

When B cells encounter an antigen, they bind to it and get activated. This activation triggers the B cells to divide and differentiate into plasma cells. Plasma cells are factories for antibody production. The antibodies produced are specific to the antigens that triggered their production.

These antibodies circulate through the bloodstream, binding to antigens and neutralizing them, making it easier for other immune cells to destroy the intruders. B cells also form memory cells, which allow the immune system to respond more rapidly if the same antigen is encountered again.

In summary:

• B cells are the only immune cells that produce antibodies.
• They become activated and differentiate into plasma cells upon encountering an antigen.
• They also form memory cells, aiding in faster future immune responses.

helper T cells

Helper T cells, also known as CD4+ T cells, are essential in regulating the immune response. They do not produce antibodies themselves but play a pivotal role in assisting other immune cells.

When a helper T cell encounters an antigen-presenting cell (APC) displaying an antigen, it gets activated. Once activated, helper T cells secrete signaling molecules called cytokines. These cytokines do several things:

• They stimulate B cells to mature and start producing antibodies.
• They enhance the activities of cytotoxic (killer) T cells and macrophages.
• They modulate the immune response to ensure it's effective and doesn't damage the body's own tissues.

Without helper T cells, the immune system's ability to fight off pathogens would be significantly weakened.

In summary:

• Helper T cells activate and regulate other immune cells through cytokine production.
• They are essential in helping B cells produce antibodies.
• They increase the activity of killer T cells and macrophages in the immune response.

killer T cells

Killer T cells, also known as cytotoxic T cells or CD8+ T cells, are integral to the immune system's ability to destroy infected or cancerous cells. They do not produce antibodies.

Instead, these cells recognize and bind to infected cells displaying viral or abnormal peptides on their surface. Upon binding, killer T cells release toxic substances like perforin and granzymes, which induce cell death in the infected cell.

This mechanism ensures that cells harboring pathogens are eliminated, preventing the spread of infection within the body. Killer T cells are especially critical in fighting viral infections and cancers.

In summary:

• Killer T cells do not produce antibodies but destroy infected or abnormal cells.
• They release toxic molecules to induce cell death in target cells.
• They are crucial for controlling viral infections and preventing cancer spread.