Increased proteolytic activity of erythrocyte membrane in spur cell anaemia

Abstract

In a case of 'spur cell anaemia' (SCA) a reduced esterified/free cholesterol ratio was found in plasma, in LDL and HDL fractions and an increased cholesterol/phospholipid (C/PL) molar ratio in erythrocyte membrane. Cation transport was normal with the exception of Li-Na counter-transport was decreased. An increased intrinsic membrane proteolytic activity (IMPA) was demonstrated by the generalized reduction or, sometimes, disappearance of protein bands on SDS-PAGE in patient ghosts when the proteolysis was allowed. This characteristic was found to be transferable to normal cells by incubation in SCA-plasma; moreover membrane C/PL molar ratio was augmented after incubation. Normal plasma was not able to normalize IMPA of SCA cells 'in vitro', even if it induced a remarkable decrease of membrane C/PL molar ratio. Nevertheless IMPA normalization did occur 'in vivo', when the SCA cells were exposed to therapeutic 'plasma exchange' (3.3 litre/week). The results suggest the following conclusions: (a) in our SCA patient there is an increased IMPA; (b) this feature, as well as membrane lipid alteration, is transferable to normal erythrocytes; (c) this case seems to demonstrate, for the first time in our knowledge, a modulating effect of plasma on IMPA in erythrocytes.

In vitro Proteolysis of the Red Cell Membrane in Patients with HIV Infection

“…Provided that, in different acquired or congenital red cell defects, in vitro proteolysis of the RBC membrane may be regarded as a marker of lesions induced in vivo from several injuries to the erythrocyte membrane [l l, [13][14][15], the results of this study seem to suggest that con ditions damaging the RBC membrane should exist during HIV infection. Therefore, we tried to correlate the proteo lysis index with some conditions previously reported to induce direct or indirect lesions on red cells or their pro genitors.…”

“…The degree of positivity was graded according to LaPierreet al [17], Erythrocyte Membrane Preparation and Study o f Proteolytic Ac tivity in RBC Membranes. Erythrocyte membranes were prepared as described elsewhere [ 13] and summarised here. Blood samples were processed by filtration through a-and mycrocristalline cellulose (ac cording to Bcutler et al [ 18]) in the presence of phenylmethylsulphonylfluoride (PMSF) 0.2 mmol/1 (final concentration).…”

“…The effects of autoantibod ies to erythrocytes (frequently reported in HIV infection) upon red blood cell (RBC) survival are poorly investi-adversely affect the maturation or survival of early erythroblasts [8], It has been shown that at least two of these conditions (splenomegaly and antibody coating of red cells) are associated with membrane architecture instabil ity in several red cell disorders [9][10][11][12], Recent reports have suggested that in vitro proteolysis of RBC mem brane proteins from some congenital or acquired red cell diseases could principally depend on alterations in mem brane architecture, induced in vivo during erythrocyte maturation or circulation. Consequently, the study of in vitro red cell membrane proteolysis could be used to eval uate possible damage to membrane stability by various injuries occurring during the red cell lifespan [13][14][15].…”

Erythrocyte Endogenous Proteinase Activity during Blood Bank Storage

“…Protein content of each sample was 40 pg, as deter mined by the method of Lowry et al [17]. Gels were stained with Coomassie brilliant blue [14], The areas under the peaks, correspond ing to the principal membrane proteins, were quantified by laser densi- proteolysis on the day of the collection and after 35 days of storage, and (B) with proteolysis permitted throughout the storage period.…”

“…Erythrocyte membranes were prepared as described elsewhere [14] and summarized here. Blood samples were processed by filtration through a-and mycrocristalline cellulose [according to Beutler.…”