Platelet discoid shape is known to correlate with in vivo viability after transfusion. Measurement of shape change requires invasive sampling and laborious assays, which is difficult to perform in a blood transfusion center as a routine test for quality control of stored platelets. The objective of this study was to establish suitability of swirling assessment in stored platelet suspension as a routine test for quality check, by comparing platelet shape change measurement carried out in parallel. The study was done in two types of bags obtained from different manufactures (Groups 1 and 2). Platelet concentrates (PC) were stored for 120 h and samples drawn at 24-h intervals, optical analysis at 540 nm was carried out to quantify shape change in response to an agonist adenosine diphosphate (ADP). The same bags were subjected to swirling assessment, by two blood bank personnel independently and graded as positive (+, ++, +++) or as negative, based on the silky appearance of the suspension. Swirling negative platelets were prepared by storing platelets at 4 degrees C for 24 h and were compared with swirling positive platelets. Other parameters studied in the samples drawn at 24-h intervals were platelet count, mean platelet volume, and blood gases. Swirling assessment results correlated well with shape change measurement at each study period with a P value significant at 0.02 and 0.04 for group 1 and 2 bags, respectively. In the negative swirling controls, extent of shape change was lower than the extent in test bags, showing reduced capacity to respond to ADP at 4 degrees C. The results of the study indicate that by simple swirling measurements, stored PC can be monitored for loss of discoid shape before they are transfused. Gas tension and pH were with in permissible limits. Therefore, inspection of swirling can be a reliable method of quality control as it correlates with platelet function. The platelets that retain the discoid shape in vitro at the time of transfusion are expected to be functional in vivo.
Normal human plasma antibody that recognizes beta-linked glucoside moiety was purified by affinity chromatography on cellulose. The anti-beta-glucoside antibody had three times higher IgA to IgG ratio and substantially higher polymeric IgA content than total serum immunoglobulins. Cellobiose and other beta-glucosides were best inhibitors of its binding to polystyrene microwell-coated polysaccharides. In synthetic glycoproteins made by conjugating disaccharides to hemoglobin or bovine serum albumin, cellobiose, unlike lactose or maltose, was sugar-specifically recognized by the antibody. It also recognized polystyrene well-coated beta1-->3 linked glycans of Saccharomyces cerevisiae, Candida albicans and of barley in decreasing order of affinity. Its sugar-binding site could thus accommodate beta-glucoside with or without substitution at C4 and C3. High IgA content along with the capacity to bind common microbial and dietary antigens pointed to the immune inflammatory potential of the antibody.
Accurate Rh testing can be difficult if the red cells are heavily coated with IgG anti D antibodies - a phenomenon called blocked D. Repeatedly, Rh D negative blood group report was obtained in a newborn male baby with severe haemolytic disease and features of kernicterus born to a 2nd gravida B Rh D negative mother. On investigation, the baby was grouped as B Rh D negative by direct grouping, but after elution, D antigen was detected and phenotyped as CcDe. Antibody was identified as anti D. All D antigens of the baby were fully saturated with anti D leaving any antigen to bind with antisera. Direct Coombs test was strongly positive even after three exchange transfusions. The baby also had free antibody apart from the red cell bound and the red cell eluate, gave a titre of 512. The mother was grouped as B Rh D negative and phenotyped as ce. She had IgM and IgG class of anti D with titres 32 and 1024 respectively. She also had IgM anti C (only in neat) and IgG anti-A with a titre of 512.
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