In Leishmania pathogenesis, which cells can suppress dendritic cells and macrophages?

• A. Apoptotic neutrophils
• B. Activated macrophages
• C. TH1 cells
• D. NK cells

Answer: (A)

In Leishmania pathogenesis, early immune evasion hinges on how dying neutrophils influence the next steps of the immune response. When neutrophils die by apoptosis at the infection site, macrophages clear them in a quiet, non-inflammatory way (a process called efferocytosis). This clearance sends anti-inflammatory signals, leading macrophages and dendritic cells to produce fewer pro-inflammatory cytokines like IL-12 and more regulatory signals such as IL-10 and TGF-β. The result is a dampened dendritic cell maturation and a weaker Th1 response, which normally activates macrophages to kill intracellular Leishmania. So apoptotic neutrophils suppress dendritic cells and macrophages, creating a permissive environment for the parasite to persist inside macrophages. In contrast, activated macrophages, TH1 cells, and NK cells tend to promote inflammation and macrophage activation, not suppression, which is why they don’t fit the scenario described.