Lymph flow and lymphatic drainage of inflammatory cells from the peritoneal cavity in a casein-peritonitis model in sheep

Abstract

The purpose of this study was to characterize the cellular responses in the peritoneal cavity and draining lymph in a sterile peritonitis model in conscious sheep. Lymph was collected from lymphatics that drained the peritoneal space (caudal mediastinal and thoracic ducts) as well as from lymph vessels that drained peripheral tissues (prescapular). Casein was used as the inflammatory agent. Dialysis solution (Dianeal 4.25%) containing 1g% casein and 25 microCi 125I-human serum albumin was infused into the peritoneal cavity in 50 ml/kg volumes. Peritoneal volumes increased from a mean infused volume of 1572 +/- 51 ml to a maximum of 2119 +/- 77 ml at 3 hours. Over 6 hours, the number of macrophages and lymphocytes in the peritoneal cavity remained relatively constant but the number of neutrophils increased from 9.9 +/- 4.2 x 10(7) to 9.2 +/- 1.9 x 10(9) total cells. Caudal lymph which drains directly from the peritoneal cavity through diaphragmatic stomata, demonstrated a 5 fold increase in flow rate over 6 hours following the Dianeal-casein infusion. Thoracic duct and prescapular flows declined approximately 70% and 50% respectively in the same time period. the concentration of lymphocytes and the lymphocyte outputs (product of volume and concentration) declined in all lymph compartments. No elevations in neutrophil numbers in the thoracic and prescapular lymph compartments were observed but neutrophil output in the caudal lymph increased steadily from 3.1 +/- 1.5 x 10(6) to 4.6 +/- 1.3 x 10(7)/hr at the 6 hour mark. We conclude that the major route of removal of inflammatory cells and fluid from the peritoneal cavity is through diaphragmatic lymphatics.