Sequestration Pattern Research Articles

Kinetics and mobilization from the spleen of indium-111-labeled platelets during platelet apheresis.

The rate and extent of platelet mobilization from the spleen were measured, and their relationship to the removal of platelets from the peripheral blood during discontinuous flow platelet apheresis was determined in four normal volunteers. Autologous platelets were labeled with Indium-111-oxine and in vivo whole body and organ In-111 radioactivity quantitated with a scintillation camera and a computer-assisted imaging system. Dynamic changes in splenic radioactivity were monitored during 12 cycles of platelet apheresis. The number of platelets harvested and changes in whole body and blood In-111 activity were determined during the procedure. The platelet life-span was estimated, and the sites of sequestration of labeled platelets was measured. Platelet apheresis removed a mean of 64 percent of platelets in the circulation; i.e., 48 percent of all platelets in the body. During the procedures, 28.0 +/- 9.4 percent In-111-labeled platelets in the body were removed, splenic radioactivity decreased by 36.5 +/- 13.2 percent, and whole body activity decreased by 34.5 +/- 9.7 percent. In-111 activity in the spleen and whole body decreased in parallel, indicating a dynamic equilibrium between these pools. The life-span of the labeled platelets was 226 +/- 25 hours, similar to that of normal subjects. The major sites of sequestration of senescent platelets were the spleen (37.9 +/- 20%) and liver (30.3 +/- 5.6%); this is similar to that found in normal subjects. We conclude that as platelets are removed from the peripheral blood, the blood pool is rapidly and effectively replenished from the splenic platelet pool. These two pools are in dynamic equilibrium and permit removal of large numbers of platelets without resultant thrombocytopenia. Platelet apheresis does not adversely effect platelet life-span, and the sequestration pattern in the reticuloendothelial system is normal.

Action of alpha-galactosidase from Clostridium sporogenes and coffee beans on blood group B antigen of erythrocytes. The effect on the viability of erythrocytes in circulation.

The effect of alpha-galactosidase, purified from Clostridium sporogenes (Maebashi), was examined on erythrocytes from rats, rabbits and gibbons. The amount of galactose released by alpha-galactosidase from Cl. sporogenes and from coffee beans was compared. The amount of sialic acid released by Vibrio cholera sialidase was also determined. Loss of blood group B specificity following treatment with alpha-galactosidase was demonstrated with anti-B lectin. In animal models, removal of all the alpha-galactosyl residues with the coffee bean or clostridial alpha-galactosidase resulted in no change in the sequestration pattern of the treated erythrocytes over a period of several days. In contrast, erythrocytes treated with sialidase were rapidly sequestered from the circulation.

The pattern of erythrocyte sequestration in immunohaemolysis. Effects of prednisone treatment and splenectomy.

The erythrocyte sequestration in the spleen and liver was investigated in 25 cases of immunohaemolysis by surface counting after infusion of 51Cr‐labelled autologous erythrocytes. The erythrocyte sequestration pattern was found to depend upon the treatment with prednisone given at the time of the investigation and furthermore upon the total haemolytic intensity.Increased sequestration of erythrocytes in the liver is always present in cases of severe hyperhaemolysis. After prednisone treatment, hypersequestration of erythrocytes in the spleen predominates. In the present study increased sequestration in the liver was even demonstrated in about 50 % of the cases in which incomplete non‐complement‐fixing antibodies were found.In the majority of cases prednisone therapy gave only short‐lasting remission. Frequently, it is difficult to reduce the dose of prednisone because of increasing haemolytic intensity.Complete, long‐lasting remission seems to follow splenectomy in cases characterized by a splenic sequestration pattern during periods without prednisone therapy, but if hepatic hypersequestration has been demonstrated the remissions are not complete. The need for steroids decreased after splenectomy in practically all cases. A combination of prednisone therapy and early splenectomy is advisable in most cases of immunohaemolysis.