True or False: Vaccinations can cause the diseases they are designed to prevent.

Explanation: B cells are a type of lymphocyte that produces antibodies against specific antigens. When a B cell encounters an antigen that matches its specific receptor, it becomes activated and differentiates into plasma cells, which are responsible for producing large quantities of antibodies that can target and neutralize the antigen.

Incorrect choices:

b. T cells are involved in cell-mediated immunity and do not produce antibodies. They recognize and directly attack infected or abnormal cells in the body.

c. Macrophages are antigen-presenting cells that engulf and process pathogens to present their antigens to other immune cells. They do not produce antibodies themselves but play a role in initiating the immune response.

d. Natural killer cells are a type of lymphocyte involved in the innate immune response. They do not produce antibodies but can directly kill infected or abnormal cells.

Explanation: The secondary immune response provides long-lasting immunity because of the presence of memory B cells and memory T cells. These memory cells "remember" the specific antigen and can quickly mount a strong and effective immune response upon re-exposure to the same antigen, providing long-term protection.

Incorrect choices:

a. The primary immune response is primarily mediated by IgM antibodies, while the secondary immune response involves the predominance of IgG antibodies, which are more effective and provide long-lasting immunity.

b. The secondary immune response occurs after the primary immune response and is faster, not slower, due to the presence of memory cells.

c. Memory cells are a key component of the secondary immune response, playing a central role in providing rapid and robust immunity.

VI. Immune Disorders and Clinical Considerations: