Compare and contrast T cells and B cells. Innate or Adaptive immunity?
A Composition of receptor?
B Process that develops receptor?
C Location of that process?
D Target of receptor?
The correct answer and explanation is:
T cells and B cells are both key players in adaptive immunity, but they have distinct roles, receptors, and developmental processes. Here’s a breakdown of their differences:
A. Composition of Receptor:
- T cells: The receptor on T cells is the T-cell receptor (TCR), which is composed of two protein chains, alpha and beta. It specifically recognizes fragments of antigens (peptides) presented by other cells on major histocompatibility complex (MHC) molecules.
- B cells: The receptor on B cells is the B-cell receptor (BCR), which is essentially a membrane-bound form of the antibody. It consists of a heavy and light chain and recognizes antigens directly, typically proteins, carbohydrates, or lipids on pathogens.
B. Process That Develops Receptor:
- T cells: The development of the TCR occurs during T cell maturation in the thymus. The TCR gene undergoes rearrangement to produce a unique receptor capable of recognizing a specific antigen. This process is driven by somatic recombination.
- B cells: The BCR is developed through a similar process called V(D)J recombination in the bone marrow, where the genes for the heavy and light chains are rearranged to create a unique receptor. This allows B cells to recognize a specific antigen.
C. Location of the Process:
- T cells: T cells undergo their receptor development in the thymus, an organ located behind the sternum. The thymus is where T cells mature and undergo selection to ensure they can recognize foreign antigens while not attacking the body’s own cells.
- B cells: B cell receptor development takes place in the bone marrow. After development, B cells migrate to secondary lymphoid organs like the spleen and lymph nodes to carry out their immune function.
D. Target of Receptor:
- T cells: TCRs target processed antigen peptides presented by MHC molecules on the surface of other cells. T cells are involved in recognizing and responding to infected cells or cancerous cells.
- B cells: BCRs target whole antigens, such as those on pathogens, viruses, or toxins. Once activated, B cells can differentiate into plasma cells and secrete antibodies to neutralize or mark these antigens for destruction.
In summary, T cells and B cells are central to adaptive immunity. T cells focus on detecting infected cells and orchestrating immune responses, while B cells are key in producing antibodies that neutralize or eliminate pathogens. Both cells undergo receptor development through genetic recombination, but the processes and locations differ.