Studies on the sequestration of chemically and enzymatically modified erythrocytes

Abstract

We have developed an experimental animal model to establish the patterns of sequestration of untreated, as well as chemically and enzymatically modified red blood cells (RBC). The intraperitoneal route of transfusion provides a useful way of transferring large numbers of untreated RBC into small animals and assuring their introduction into the circulation within 24 hr. Moreover, this route "filters" some types of modified erythrocytes, eg, glutaraldehyde treated RBC. From the pattern of sequestration, the RBC in the peritoneal cavity then pass through the liver where other types of modified RBC are sequestered, eg, after trypsin, pronase, protease, or sialidase treatment. Some modified RBC show a preference for the spleen as the site of sequestration, eg, galactose oxidase or N-ethylmaleimide treated RBC. These appear in the spleen despite intraperitoneal transfusion. Relevant to this study is the observation that in the rat old RBC are sequestered both by liver and spleen, while asialoerythrocytes are sequestered by liver only. A possible reason for this difference is discussed in the text.

Use of 75se‐labeled methionine to study the sequestration of senescent red blood cells

“…2) The senescence factor glycopeptide isolated from old RBC is not detectable in the tryptic digests derived from asialo-RBC [15]. 3) Asialo-RBC are sequestered in the liver of the rat, while senescent RBC are predominantly removed by rat spleen [16]. 4) As we have demonstrated here, unlabeled asialo-RBC readily inhibit the sequestration of labeled asialo-RBC but have no effect on the uptake of naturally senescent RBC.…”

“…In a preceding paper [16] we described a method to separate young and old rat RBC employing the principle that old RBC have a higher density than young RBC [22]. Thus, Percoll-separated young and old RBC were randomly tagged with "Cr and reinjected IP or IV to study the mechanism of their sequestration from circulation.…”

“…Intravenous transfusions (IV) were performed by injection into the tail or tongue vein using 27 G needles. Intraperitoneal (IP) transfusions were done as described previously [16] by inserting a 21 G needle into the peritoneal cavity, taking care not to pierce the intestines. The IP route of injection was chosen when volumes of more than 2 ml were to be administered.…”

“…It soon became apparent, however, that it was inadequate as a model [6,. We have demonstrated that the sites for sequestration of asialo and senescent red cells are not the same [16]. A better biological assay is needed to follow the dynamics of sequestration.…”

Influence of Platelet Membrane Sialic Acid and Platelet-Associated IgG on Ageing and Sequestration of Blood Platelets in Baboons

“…The exponential correlation between the shortening of MPLS and the amount of sialic acid removed (Fig.2) probably has little resemblance to the normal process of in vivo platelet aging. It is probable that treatment with neuraminidase removes more sialic acid than is necessary to signal senescence (2,21). The correlation nevertheless implies that sialic acid plays a part in the determination of MPLS, and thus in the mechanism of platelet senescence.…”