Reticuloendothelial system function and humoral factor deficiency following acute hemorrhage.

The present study has shown that following acute hemorrhage (equivalent to 3% body weight withdrawn over 20 min) in the rat, there is a large reduction (56% of control) in circulating alpha-2-glycoprotein opsonic activity. The reduction in this plasma opsonic activity was near maximal by the completion of blood withdrawal and was maintained throughout a 2-h hypotension period. There was no trend toward recovery of the opsonic activity when evaluated 15 min following reinfusion of shed blood in animals that were hypotensive for 0, 30, and 120 min. Reticuloendothelial system (RES) phagocytic function, as assessed from the carbon clearance rate (phagocytic index) following reinfusion of the shed blood, was depressed in animals that were hypotensive for 0, 30, and 120 min. Thus, phagocytic index followed a time course similar to the depression of opsonic activity. The observed close temporal relationship between alpha-2-glycoprotein opsonic deficiency and depression of RES clearance further supports the possible role of a humoral opsonic deficiency in mediating the RES phagocytic depression during circulatory shock.     

Iron Metabolism in the Reticuloendothelial System

Comprised mainly of monocytes and tissue macrophages, the reticuloendothelial system (RES) plays two major roles in iron metabolism: it recycles iron from senescent red blood cells and it serves as a large storage depot for excess iron. Although iron recycling by the RES represents the largest pathway of iron efflux in the body, the precise mechanisms involved have remained elusive. However, studies characterizing the function and regulation of Nramp1, DMT1, HFE, FPN1, CD163, and hepcidin are rapidly expanding our knowledge of the molecular aspects of RE iron handling. This review summarizes fundamental physiological and biochemical aspects of iron metabolism in the RES and focuses on how recent studies have advanced our understanding of these areas. Also discussed are novel insights into the molecular mechanisms contributing to the abnormal RE iron metabolism characteristic of hereditary hemochromatosis and the anemia of chronic disease.     

Reticuloendothelial function in renal allograft recipients.

The phagocytic capacity of the reticuloendothelial system (R.E.S.) was assessed in patients with chronic renal failure and in renal transplant recipients. R.E.S. phagocytosis was increased in the former group. Soon after transplantation R.E.S. phagocytosis was moderately reduced (through levels were comparable with those of normal controls) but was particularly reduced after high-dose corticosteroid treatment for rejection. In long-term allograft recipients R.E.S. phagocytosis was also depressed though steroid maintenance doses were small.     

Oestrogen as a Reticuloendothelial Stimulant in Patients with Cancer

Stimulation of reticuloendothelial activity may benefit patients with cancer. Oestrogenic compounds are known to stimulate reticuloendothelial phagocytic activity in animals and a similar effect is demonstrated in patients.The depression of reticuloendothelial phagocytic activity which follows radiotheraphy in the treatment of cancer can be prevented by the simultaneous administration of stilboestrol. Possibly this could be associated with a more favourable response to therapy, and a controlled trial is needed to establish this.     

Suppression of Reticuloendothelial Function in the Rat with Cyclophosphamide

Effects of cyclophosphamide immunosuppressive therapy upon reticuloendothelial function in the rat have been studied. Numerous side effects including leukopenia, hematuria, diarrhea, hemorrhagic cystitis, and petechial hemorrhage in the lungs and the small bowel were observed. Studies utilizing (32)P-labeled bacteria revealed no change in the ability of the liver, spleen, lungs, or kidneys to ingest Pseudomonas aeruginosa. Utilization of labeled Staphylococcus aureus revealed an impairment of splenic uptake in animals receiving the maximal dose of 100 mg/kg. However, the liver, lungs, and kidneys were not affected. Although no generalized defect in the ingestive powers of these organs was observed, the ability of the lungs and kidneys from treated animals to kill ingested bacteria was significantly impaired. Regardless of the bacterium employed, the lungs and kidneys revealed a decrease in bactericidal ability with increasing drug dosages. Neither the liver nor the spleen from treated animals exhibited any decrease in bactericidal effect. Possible causes of this reduction in the bactericidal ability of alveolar and renal tissue following immunosuppression with cyclophosphamide are discussed.     

Flow Cytometric Method Using Fluorescent Microspheres to Measure Reticuloendothelial Function or Particulate Translocation

The reticuloendothelial system (RES) influences the outcome of vascular shock and environmental stress. We describe a procedure that employs flow cytometry and 1 μm fluorescent microspheres (FM) to study RES function. FM (2 × 10¹⁰ beads/kg) were administered via a jugular cannula in Sprague-Dawley rats. After 15 min, blood and tissues were collected and digested in 15% KOH. Phycoerythrin 1 μm beads were added to each sample as an internal standard and analyzed by flow cytometry. FM were preferentially cleared by the spleen, liver and lung. Clearance was confirmed by fluorescent photomicroscopy. Addition of the internal standard to determine accurately aspiration volume enhanced precision. This procedure offers advantages over other RES clearance methods including bacterial, radioactive or carbon clearance assays. Moreover, this method could enhance accuracy, reproducibility and speed of data collection in particulate transport studies that are based on manual microscopic scanning and FM counting.