Final answer:
Memory T cells are integral to the adaptive immune system's memory response, maintaining antigen specificity from the primary encounter and enabling a swift secondary response upon re-exposure to the same pathogen without the requirements typical for naïve T cells activation. Hence the correct answer is option e: All of the above.
Step-by-step explanation:
The question refers to the characteristics of memory T cells in the adaptive immune system. According to the information provided, memory T cells are a critical component of the adaptive immune system, enabling it to respond more quickly and effectively to pathogens the body has previously encountered.
These cells are long-lived and retain antigen specificity from the primary immune response.
Options regarding memory T cells include:
- (a) Memory T cells will be of the same type that were established in the primary immune response. This means they maintain the specific antigen recognition capabilities from the original encounter.
- (b) Memory T cells can sometimes be activated directly at the site of infection, accelerating the immune response.
- (c) Memory T cells do not undergo somatic hypermutation or isotype switching, unlike B cells. These processes are part of the activation and differentiation of B cells.
- (d) Memory T cells do not require CD28 for co-stimulation, indicating a unique activation pathway compared to naïve T cells.
In summary, the answer to the question on the characteristics of memory T cells as presented in the options would be (e) All of the above.