Microbiology Practice Exam

Which type of lymphocyte is responsible for specific immunity?

1. B-cells

2. T-cells

3. Natural killer cells

4. All of the above

The correct answer is: All of the above

The correct response recognizes that all listed lymphocyte types contribute to the immune response, but the key focus is on specific immunity. B-cells and T-cells play direct roles in adaptive (specific) immunity, which is tailored to target specific pathogens. B-cells are primarily responsible for the production of antibodies, which are proteins that specifically recognize and neutralize pathogens. This adaptive response allows for immunological memory, meaning that once B-cells encounter a pathogen, they can produce a faster and more effective response upon re-exposure. T-cells, particularly helper T-cells and cytotoxic T-cells, play essential roles in regulating the immune response and directly attacking infected cells, respectively. Helper T-cells orchestrate the immune response by releasing cytokines that stimulate the activity of B-cells and other immune cells, while cytotoxic T-cells are crucial for killing infected or cancerous cells. Natural killer cells contribute primarily to innate immunity, providing a first line of defense against tumors and virally infected cells through non-specific mechanisms. Their actions are not tailored to specific pathogens, distinguishing them from B-cells and T-cells. In summary, B-cells and T-cells are both integral to specific immunity due to their ability to recognize