P2RX7 and infection: Legionella[82], Francisella[83], [84], and Leishmania[85] prevent phagolysosome fusion—perhaps this is in a P2X7 receptor–dependent manner analogous to Chlamydia? And, although no definitive link with the P2X7 receptor exists, infection of peritoneal macrophages with Trypanosoma cruzi down-regulates expression of P2X7 receptors [86], which may reduce the immune pressure on these parasites.