Label the figure with the items provided. Helper T-lymphocyte BCR CD8 protein Cytotoxic T-lymphocyte TCR T-lymphocytes: Cells of cell-mediated immunity B-lymphocyte: Cell of humoral immunity CD4 protein Reset Zoom Type here to search
The correct Answer and Explanation is:
To provide a complete and accurate answer, I would need to see the figure you’re referring to. Please upload the image or describe the figure so I can match the correct labels to the appropriate parts. However, I can still explain how each of the listed items is typically related and where they would commonly appear in an immune system diagram. Once you upload the figure, I can label it precisely.
Explanation
The immune system comprises two main branches: cell-mediated immunity and humoral immunity. Both rely on different types of lymphocytes—specialized white blood cells.
T-lymphocytes, or T-cells, are central to cell-mediated immunity. There are two major types:
- Helper T-lymphocytes (CD4+ T-cells): These cells express the CD4 protein on their surface and are activated when their T-cell receptor (TCR) recognizes an antigen presented by an antigen-presenting cell (APC) on MHC class II molecules. Once activated, they release cytokines that stimulate other immune cells.
- Cytotoxic T-lymphocytes (CD8+ T-cells): These express the CD8 protein and are activated when their TCR recognizes an antigen bound to MHC class I molecules. They directly kill infected or cancerous cells.
B-lymphocytes, or B-cells, are responsible for humoral immunity. They have B-cell receptors (BCR) on their surface, which bind directly to free-floating antigens. Once activated (often with help from helper T-cells), B-cells differentiate into plasma cells that secrete antibodies, which neutralize pathogens.
Here’s a brief overview of how the labels correspond:
- Helper T-lymphocyte: Has TCR and CD4 protein; part of cell-mediated immunity.
- Cytotoxic T-lymphocyte: Has TCR and CD8 protein; also part of cell-mediated immunity.
- B-lymphocyte: Has BCR; central to humoral immunity.
- T-lymphocytes: Cells of cell-mediated immunity: General category including helper and cytotoxic T-cells.
- B-lymphocyte: Cell of humoral immunity: Identifies the role of B-cells in producing antibodies.
