The mechanism of cross-presentation by dendritic cells is an essential pathway for generating CD8 T cell responses to some intracellular pathogens. If this pathway did not exist, we would be highly susceptible to: Intracellular pathogens that can survive inside macrophage endocytic vesicles Intracellular pathogens that are able to evade antibody responses Intracellular pathogens that do not infect and replicate in dendritic cells Intracellular pathogens that can spread from cell to cell by inducing cell fusion Intracellular pathogens that infect and replicate in red blood cells

Multiple pathways for regulating complement activation limit the potential damage caused by complement deposition on host cells or caused by the spontaneous activation of complement proteins in the plasma. Genetic deficiencies in these mechanisms often lead to chronic inflammatory diseases, but in some cases can paradoxically lead to increased susceptibility to bacterial infections. This latter outcome may occur because: Complement regulatory proteins have dual functions in inhibiting and promoting complement activation. Uncontrolled complement activation leads to the depletion of serum complement proteins. The inhibition of the membrane attack complex by complement regulatory proteins normally leads to enhanced activation of the early steps of the complement pathway. Complement regulatory proteins normally cause the rapid depletion of plasma complement factors. Uncontrolled complement activation recruits the majority of phagocytic cells, leaving few remaining to fight infections in…

Which of the following steps are part of the processing of antigen by immune cells? Select all that apply.   The vesicle containing the antigen fuses with a lysosome.   Enzymes in the lysosome digest the antigen into components that bind to MHC markers.   The antigen is initially released from the phagocytic cell via exocytosis.   The antigen-MHC complex becomes displayed on the cell's interior.

Based on this figure which specific immune response could be measured to determine whether someone had been infected with Sar-Co-V2 six weeks after they were sick, but had recovered from infection?