These are known to the body as foreign as they are expressed as '''pathogen-associated molecular patterns''' (PAMPs) which are recognised by '''pattern recognition receptors''' (PRRs) expressed on mammalian cells. These receptors are expressed on many different cell types, not just on phagocytes, though not all are expressed by all cells: different cell types express a different range of PRRs. PRRs are either intracellular, membrane-associated or soluble: | These are known to the body as foreign as they are expressed as '''pathogen-associated molecular patterns''' (PAMPs) which are recognised by '''pattern recognition receptors''' (PRRs) expressed on mammalian cells. These receptors are expressed on many different cell types, not just on phagocytes, though not all are expressed by all cells: different cell types express a different range of PRRs. PRRs are either intracellular, membrane-associated or soluble: |