A comparative study of the sequestration of "abnormal" red cells by the spleen

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Abstract
Splenic uptake of abnormal red cells, during a single transit, was studied using an isolated perfused cat spleen preparation. The organ was perfused at a constant pressure (60-65 mmHg; 1 mmHg = 133.322 Pa [Pascals]) with phosphate-buffered Ringer solution of pH 7.4 and equilibrated at 37.degree. C with 5% CO2 in O2. Venous pressure was maintained at 4-6 mmHg. When most of the red cells had been washed out a small bolus of cell suspension, consisting of 1.0 .times. 109 to 1.6 .times. 109 abnormal red cells, was injected into the arterial inflow and rapid, serial sampling of the outflow was carried out. Cell concentrations in the samples were measured by an electrical impedance type counter. The abnormal cells were autologous red cells damaged with heat (49.5.degree. C for 20 min), neuraminidase, N-ethylmaleimide (NEM) or glutaraldehye, red cells previously drained from the splenic pulp, or human red cells. There appears to be no single, key property of the cells that uniquely determines whether or not sequestration within the spleen will occur. Glutaraldehyde-treated cells (normal discoid shape but nondeformable) became trapped completely within the spleen and 90% of injected human red cells were retained. Autologous red cells from the splenic pulp and cells treated with neuraminidase or NEM (8-16 .mu.mol/ml) were all sequestered equally (75%) whereas only 57% of heat-treated cells became trapped. Cells damaged more severely by NEM (20-30 .mu.mol/ml) were retained to a smaller extent (30%). Marked saturation of the trapping mechanism occurred when 2nd or 3rd injections of abnormal cells were made. The extent of sequestration depends on the specific nature of the red cell abnormality, the degree of abnormality and the number of abnormal cells injected.