Formation and disappearance of pocked erythrocytes: Studies in human subjects and laboratory animals

Abstract

The pocked or "pitted" RBC count is being increasingly utilized as a test of splenic function. Since little is known about patterns of formation and removal of the characteristic organelles in the pocked RBC, we performed serial pocked RBC counts following splenectomy in six patients and in three animal species (dogs, rats, and rabbits). In the patients, pocked RBC counts began to rise within 1 week following splenectomy and reached a plateau (40-60%) by 60-100 days. Similar results were obtained following splenectomy of dogs, except that the plateau value was less. Pocked RBCs in splenectomized rats rose initially, but after the sixth week there was a progressive decline in their numbers; splenosis or accessory spleens were not visualized at autopsy. Rabbits had only a slight and inconsistent rise in pocked RBCs after splenectomy. When the rate of removal of pocked RBCs from the circulation was determined by transfusion of blood from splenectomized dogs in eusplenic animals, the pocked RBC count rapidly decreased within 3 to 6 hours. Pocked RBCs did not disappear when crosstransfused into a splenectomized recipient animal. Prior treatment of the recipient dog with either corticosteroids or vincristine did not affect the pattern of removal of pocked RBCs. We conclude that pocked RBCs rise slowly following splenectomy, disappear rapidly from the circulation in the presence of a normal spleen, and vary in pattern of rise and peak levels following splenectomy of different laboratory animals.

Formation of Intracellular Vesicles in Neonatal and Adult Erythrocytes: Evidence against the Concept of Neonatal Hyposplenism

“…Unfortunately, our study does not exclude the possibility that an additional component of the increased vesiculation could be due to a concomitant impairment of splenic clearance. Experimental studies suggest that the spleen might be capable of removing a 5-fold increase in erythrocyte vesicles, but the applicability of these studies in adult dogs is unknown (46). However, considering our data, the weakness of the other data supporting impairment of splenic function in the neonate, and the normal ability of the neonatal spleen to clear sulfur-colloid and heat-damaged red cells, we suggest that the concept of neonatal hyposplenism should be challenged.…”

Hyposplenism from Mycobacterium avium Complex Infection in a Patient with AIDS and Immune Thrombocytopenia

“…Since 20–30% of patients with HIV-related ITP will not respond to splenectomy and estimates are that 15–25% of all AIDS patients will develop disseminated MAC infection [17], the clinical scenario described in this report may become more common. Under these circumstances we recommend that splenic function be evaluated by radionuclide scan and examination of the blood smear for pitted erythrocytes [18] and Howell-Jolly bodies before proceeding to splenectomy, along with the usual bone marrow examination. If splenic hypofunction is documented, alternatives to splenectomy should be considered.…”

Intra-erythrocytic vacuoles in asplenic patients: elusive genesis and original clearance of unique organelles

“…Spleens of humans, rats and dogs display a sinusal structure as opposed to spleens of mice, cats and horses ( Bowdler, 2001 ). In splenectomized mice, rats, and rabbits, vacuoles have been observed in RBC but their proportion increase only slightly, to less than 10% of all RBC after splenectomy ( Buchanan et al, 1987 ; Shet et al, 2008 ). In mice and rats, the mean proportion of pocked RBC quantified by DIC was 0.4% and 3%, 63 days and 100 days post-splenectomy, respectively ( Buchanan et al, 1987 ; Shet et al, 2008 ).…”

“…In splenectomized mice, rats, and rabbits, vacuoles have been observed in RBC but their proportion increase only slightly, to less than 10% of all RBC after splenectomy ( Buchanan et al, 1987 ; Shet et al, 2008 ). In mice and rats, the mean proportion of pocked RBC quantified by DIC was 0.4% and 3%, 63 days and 100 days post-splenectomy, respectively ( Buchanan et al, 1987 ; Shet et al, 2008 ). In rabbits, a transient increase from 2.5% to 10% in the first 45 days was observed, but the proportion returned to baseline 90 days after splenectomy ( Buchanan et al, 1987 ).…”

“…In mice and rats, the mean proportion of pocked RBC quantified by DIC was 0.4% and 3%, 63 days and 100 days post-splenectomy, respectively ( Buchanan et al, 1987 ; Shet et al, 2008 ). In rabbits, a transient increase from 2.5% to 10% in the first 45 days was observed, but the proportion returned to baseline 90 days after splenectomy ( Buchanan et al, 1987 ). Only dogs showed proportions similar to those observed in humans with pocked RBC reaching a plateau at 100 days post-splenectomy.…”