S1PR4 and peritonitis: In contrast to observations made in the model of sterile peritonitis, where transferred peritoneal s1pr4−/− B1a B cells showed increased peritoneal cell numbers 72 h after i.p. LPS injection, B1a B cell numbers were lower in s1pr4−/− animals compared to wt animals both 24 h and 7 days after peritonitis induction.