Question

Macrophages were isolated from either the spleen or the intestinal lamina propria and stimulated in vitro with the TLR ligands LPS or CpG. Twenty-four hours later, the culture supernatants were tested for the amounts of IL-10 and IL-12. Macrophages from the spleen produced low levels of IL-10 when stimulated with either ligand and a high level of IL-12 in response to CpG stimulation. In comparison, the macrophages isolated from the intestine produced high levels of IL-10 when stimulated with either LPS or CpG, and they did not secrete IL-12 in response to stimulation with either TLR ligand. These results indicate that the lamina propria macrophages

Question options:

function as anti-inflammatory cells.


make robust responses to a variety of MAMPs.


are less efficient at cytokine production than splenic macrophages.


promote epithelial cell repair in case of disruptions in the intestinal barrier.


are unable to respond to TLR stimulation.


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Answer 1

Intestinal lamina propria macrophages primarily function as anti-inflammatory cells, indicated by their high IL-10 production and lack of IL-12 secretion in response to TLR ligands, which helps in maintaining gut immune homeostasis and protecting mucosal surfaces.

Step-by-step explanation:

Based on the provided experiment outcomes, macrophages isolated from the intestinal lamina propria produce high levels of IL-10, an anti-inflammatory cytokine, when stimulated with TLR ligands LPS or CpG, but do not secrete the pro-inflammatory cytokine IL-12. This contrasts with spleen-derived macrophages that produce a high level of IL-12 in response to CpG stimulation, indicating a pro-inflammatory response. These differences suggest that lamina propria macrophages primarily function as anti-inflammatory cells within the intestinal mucosal immune system. Their role is crucial in maintaining immune homeostasis in the gut, preventing excessive inflammation which could damage the tissue and disrupt the intestinal barrier.

The immunological context provided is important for understanding the specialized functions of macrophages in different tissue environments. In the spleen, macrophages seem poised to mount a strong pro-inflammatory response, likely to deal effectively with pathogens entering the blood. In contrast, intestinal lamina propria macrophages favor the secretion of IL-10 to counter inflammatory responses, playing a role in protecting the mucosal surfaces and promoting an anti-inflammatory milieu which can be beneficial in preventing tissue damage from constant exposure to foreign substances.