Which term best fits with T cells that reside within the lamina propria of the GALT?
a) non-active
b) anergic
c) antibody secreting
d) apoptotic
e) activated
f) naive
The correct answer and explanation is:
Correct answer: e) activated
Explanation (Approximately 300 words):
The lamina propria of the gut-associated lymphoid tissue (GALT) is a critical site in the immune system where the body balances immune tolerance and defense, especially against the massive antigen load presented by food and the gut microbiota.
T cells that reside in the lamina propria of GALT are primarily activated T cells. These cells have been previously exposed to antigens, often in the Peyer’s patches or mesenteric lymph nodes, and have migrated to the lamina propria in an effector or memory state. In this location, they are poised to respond rapidly to pathogens that breach the intestinal barrier.
Unlike naïve T cells, which circulate in blood and secondary lymphoid organs waiting to encounter antigens, T cells in the lamina propria have already been primed by antigen-presenting cells. They express activation markers, produce cytokines like interferon-γ (IFN-γ) or IL-17, and contribute to both immune protection and regulation of inflammation. Their continuous activation is modulated by the gut environment, including interactions with epithelial cells, microbiota, and regulatory T cells to prevent excessive inflammation or autoimmunity.
Other options do not correctly describe these cells:
- a) Non-active and f) naïve: These terms imply the T cells have not yet encountered antigen, which is not the case.
- b) Anergic: Anergic T cells are unresponsive due to antigen encounter without costimulation, which does not apply to most lamina propria T cells.
- c) Antibody-secreting: This describes B cells or plasma cells, not T cells.
- d) Apoptotic: These cells are not in a dying state; they are functionally active.
Thus, the best description for T cells in the lamina propria of GALT is “activated.”