Rare and transient anti-D antibody response in D(-) liver transplant recipients transfused with D(+) red blood cells.

A retrospective analysis was conducted on 20 D(-) liver transplant (LT) recipients transfused with D(+) RBCs perioperatively and screened for RBC antibodies between 2 and 6 months later. None developed anti-D detectable by the indirect antiglobulin test. Two patients produced weak anti-D that reacted only with papain-treated RBCs at 10 and 11 days without any sign of immune haemolysis. Antibodies became quickly undetectable. These data suggest an unusual pattern of alloimmunization in LT recipients with rapid, weak and transient antibody response and support the safety of transfusing D(+) RBCs in most of D(-) patients during LT surgery.

In vitro characteristics of cryopreserved platelet concentrates reconstituted by fresh frozen or lyophilized plasma.

BACKGROUND AND OBJECTIVES: Six percent dimethyl sulfoxide (DMSO) cryopreservation of platelet concentrates (PCs) allow longer storage of PCs but require time-consuming post-thaw washing. An alternative process based on removing supernatant before freezing has been implemented in several centres worldwide. We assessed the in vitro characteristics of cryopreserved PCs (CPPs) prepared according to this latest process using either French lyophilized plasma (FLyP) or fresh frozen plasma (FFP) for reconstitution. FLyP provides additional benefits to the process due to its logistical constraints and quick availability. MATERIALS AND METHODS: Apheresis PCs (n=16) and buffy coat PCs (n=16) were cryopreserved in 6% DMSO. After storage at -80°C, PCs were thawed and reconstituted with FFP or FLyP. Volume, residual leukocytes, total platelet counts (TPCs), post-thaw recovery, biochemical parameters, and DMSO concentration were assessed. Platelet functions were analysed by swirling index, viscoelastometric assay and CD62P quantification. RESULTS: After reconstitution, TPC was above 2.1011/CPs; recovery was 78±14% with no significant difference between FFP and FLyP. Glucose and lactate levels were not different between plasmas, whereas FLyP-CPPs exhibited a significant increase in LDH and significantly lower pH. Residual DMSO was 8±4G/L. Functional analysis revealed significant differences between FFP and FLyP-CPPs, with lower clot firmness and increased clot initiation. Activation of platelets was not higher in FLyP-CPPs. CONCLUSION: Preparing CPPs according to this "new" process fulfilled the French legal criteria regardless of the type of plasma. Differences highlighted between FFP-CPPs and FLyP-CPPs were unlikely to be of clinical relevance.

Removing IgG antibodies from intact red cells: comparison of acid and EDTA, heat, and chloroquine elution methods.

BACKGROUND: To accurately phenotype red cell from patients with a positive direct antiglobulin test (DAT), nonlytic elution procedures were assessed for their ability to dissociate IgG from antibody-coated red cells without altering red cell antigen expression. STUDY DESIGN AND METHODS: Antibodies coating red cells that were sensitized in vivo (warm-reactive autoantibodies: 8 patients) or in vitro (42 alloantibodies) were eluted by using glycine-HCl and EDTA (acid/ EDTA), heat (56 degrees C, 10 min), or chloroquine method. RESULTS: Acid/EDTA elution gave the best results, reducing DAT positivity to microscopic levels or rendering the DAT negative in 48 of 50 instances, whereas 4 samples remained resistant to heat elution and 24 to chloroquine. Standard DAT agglutination scores demonstrated that both acid/EDTA and heat elution were superior to the chloroquine method (p < 0.0001). With the gel low-ionic-strength saline indirect antiglobulin test, acid/ EDTA was superior to heat (p < 0.001). Overall, acid/ EDTA elution dissociated more antibodies than heat (p < 0.0001), especially for Kell system (K, k, Kpa, Kpb) alloantibodies. Common red cell antigens, other than Kell system antigens, were unaffected by acid/EDTA elution. In contrast, the expression of most blood group antigens was diminished after heat elution. However, it was possible to type red cell antigens by using gel low-ionic-strength saline indirect antiglobulin tests or tube agglutination methods. CONCLUSION: Although heat elution may be used on a limited basis, the acid/EDTA method appears to be the procedure of choice for typing red cell coated with warm-reactive IgG alloantibodies or autoantibodies.

A microtiter plate assay for measurement of serum alanine aminotransferase in blood donors.

BACKGROUND: Alanine aminotransferase (ALT) testing in blood donors is required in many countries as a surrogate test for viral hepatitis. Current automated ALT assays do not fulfill some operational requirements of blood banks. STUDY DESIGN AND METHODS: The standard ALT measurement method of the International Federation of Clinical Chemistry was adapted to the 96-well microtiter plate to obtain optimal conditions. The method was compared with a reference biochemical method using an analyzer on 251 serum samples. RESULTS: The analytical variability was minimal (2.3% for an ALT level of 59 IU/L and 3.6% for an ALT level of 33 IU/L) after a total analysis time of 8 minutes and a time of 7 minutes before the first reading. With these measures, a linear standard curve was obtained in the range of 10 to 130 IU per L.A computerized validation procedure allowed rejection of samples with high ALT levels. Comparison with the analyzer gave a correlation coefficient, r = 0.935. The method proved to be efficient and time-saving in routine use over an 8-month period. CONCLUSION: The microtiter plate ALT assay is helpful in allowing the simultaneous distribution of ALT and immunoenzymatic assays. It provides accurate results and a minimal risk of false-negative results.

Detection of HIV-1 RNA in two consecutive blood donations screened negative for HIV antibodies.

BACKGROUND AND OBJECTIVES: An unusual serological pattern of HIV-1 seroconversion in a blood donor is described. The seroconversion panel was used to investigate the sensitivity of existing screening assays. MATERIALS AND METHODS: A volunteer blood donor who had given blood 79 times was diagnosed anti-HIV-1-antibody-positive. The heteroduplex mobility assay identified a subtype B HIV-1 strain. The frozen plasmas from the last four blood donations had been kept at -30 degrees C. They were thawed and aliquoted for subsequent testing. RESULTS: The last two blood donations contained HIV-1 RNA, 2,800 copies/ml (October 26) and 170 copies/ml (November 23). Weak anti-p24 antibodies were detected by Western blot in the October 26 sample, and a clear p24 reactivity along with a faint gp160 reactivity was observed on November 23. HIV p24 antigen was undetectable in both samples. Out of 13 screening assays, only 6 gave positive results on the November sample and 7 negative results which were obtained by 1 competitive enzyme immunoassay (EIA) and 6 of the 9 sandwich EIAs. CONCLUSION: Most sandwich EIAs gave prolonged false-negative results in the present case. p24 antigen testing was negative and would not have reduced the risk of HIV transmission.