Transfusión de hematíes D positivo a pacientes seleccionados D negativo / Transfusion of D positive red cells to selected D-negative patients

INTRODUCCIÓN: La transfusión isogrupo ABO D es la práctica transfusional habitual, sin embargo, cuando no se dispone de sangre D negativo puede ser preciso transfundir concentrados de hematíes D positivo a pacientes D negativo. Estos pacientes pueden desarrollar aloanticuerpos anti-D en los siguientes 3 meses a la exposición. MATERIAL Y MÉTODO: En los últimos 18 años, hemos experimentado situaciones de escasez de sangre D negativo, en las que hemos aplicado un protocolo clínico asistencial, seleccionando s los pacientes según el riesgo de aloinmunización y de requerimientos transfusionales crónicos. Se realizó una recogida prospectiva de estos pacientes, analizando principalmente la aloinmunización y la mortalidad. RESULTADOS: Tras las aplicación del protocolo se han transfundido unidades D positivo al 3% de los pacientes D negativo, con una tasa de aloinmunización conocida del 12,3%, siendo mayor en los pacientes más jóvenes y en aquellos que han recibido mayor número de unidades. No se detectaron complicaciones secundarias a la inmunización y la mortalidad en este grupo fue menor. CONCLUSIÓN: La transfusión de hematíes D positivo a pacientes D negativo no solo es una práctica segura para pacientes seleccionados, sino que además permite optimizar el uso de un producto en situaciones de escasez

BACKGROUND: To transfuse packed red blood cells isogroup ABO D is a usual transfusion practice. However, when there is not enough D negative blood available, we can transfuse positive red blood cells to negative patients. Immunocompetent D negative individuals may develop serologically detectable anti-D antibodies within 3 months after exposure to D positive red blood cells. MATERIAL AND METHOD: Over the last 18 years, we have experienced situations of D negative blood cell scarcity. In these situations, we have applied a clinical assistance protocol, selecting patients with lower risk of alloimmunization and chronic transfusion requirements. We have retrospectively evaluated this policy for the use of D positive red blood cells in D negative patients, focussing on alloinmunization and mortality. RESULTS: Applying the protocol, 3% of D negative patients were transfused with D positive units, with an alloimmunization rate of 12.3%. The rate of alloimmunization was higher in the younger age group and in those transfused with more units. No haemolytic reactions were reported. Mortality in the alloimmunized group was lower. CONCLUSION: The use of D positive red blood cells in selected D negative patients does not induce adverse reactions, is a safe practice and allows saving of a product that is sometimes limited

Transfusion of D positive red cells to selected D-negative patients. / Transfusión de hematíes D positivo a pacientes seleccionados D negativo.

BACKGROUND: To transfuse packed red blood cells isogroup ABO D is a usual transfusion practice. However, when there is not enough D negative blood available, we can transfuse positive red blood cells to negative patients. Immunocompetent D negative individuals may develop serologically detectable anti-D antibodies within 3 months after exposure to D positive red blood cells. MATERIAL AND METHOD: Over the last 18 years, we have experienced situations of D negative blood cell scarcity. In these situations, we have applied a clinical assistance protocol, selecting patients with lower risk of alloimmunization and chronic transfusion requirements. We have retrospectively evaluated this policy for the use of D positive red blood cells in D negative patients, focussing on alloinmunization and mortality. RESULTS: Applying the protocol, 3% of D negative patients were transfused with D positive units, with an alloimmunization rate of 12.3%. The rate of alloimmunization was higher in the younger age group and in those transfused with more units. No haemolytic reactions were reported. Mortality in the alloimmunized group was lower. CONCLUSION: The use of D positive red blood cells in selected D negative patients does not induce adverse reactions, is a safe practice and allows saving of a product that is sometimes limited.

Identification of six new RHCE variant alleles in individuals of diverse racial origin.

BACKGROUND: The introduction of molecular methods into routine blood typing is prompting the identification of new blood group alleles. Discrepancies between the results of genotyping and serology or chance events uncovered during genotyping prompted additional investigations, which revealed six new RHCE variant alleles. STUDY DESIGN AND METHODS: Samples from eight blood donors, two patients (one prenatal), and a patient's relative, all of diverse racial origin, were analyzed by standard serology methods, targeted genotyping arrays, DNA sequencing, and allele-specific polymerase chain reaction. RESULTS: Six new RHCE alleles were identified, namely, RHCE*cE84A, RHCE*ce202G, RHCE*ce307T, RHCE*Ce377G, RHCE*ce697G,712G,733G,744C, and RHCE*Ce733G. CONCLUSION: While implementation of new assays in commercial genotyping platforms to detect the polymorphisms reported here may not be justified given their apparent rarity, software interpretative algorithms may benefit from the identification of new alleles for a more accurate determination of genotypes and prediction of phenotypes.

Screening for occult malignancy with FDG-PET/CT in patients with unprovoked venous thromboembolism.

Extensive screening strategies to detect occult cancer in patients with unprovoked venous thromboembolism (VTE) are complex and no benefit in terms of survival has been reported. FDG-PET/CT (2-[F-18] fluoro-2-deoxy-D-glucose positron emission tomography combined with computed tomography), a noninvasive technique for the diagnosis and staging of malignancies, could be useful in this setting. Consecutive patients ≥ 50 years with a first unprovoked VTE episode were prospectively included. Screening with FDG-PET/CT was performed 3-4 weeks after the index event. If positive, appropriate diagnostic work-up was programmed. Clinical follow-up continued for 2 years. Blood samples were collected to assess coagulation biomarkers. FDG-PET/CT was negative in 68/99 patients (68.7%), while suspicious FDG uptake was detected in 31/99 patients (31.3%). Additional diagnostic work-up confirmed a malignancy in 7/31 patients (22.6%), with six of them at early stage. During follow-up, two patients with negative FDG-PET/CT were diagnosed with cancer. Sensitivity (S), positive (PPV) and negative predictive values (NPV) of FDG-PET/CT as single tool for the detection of occult malignancy were 77.8% (95% CI: 0.51-1), 22.6% (95% CI: 0.08-0.37) and 97.1% (95% CI: 0.93-1), respectively. Median tissue factor (TF) activity in patients with occult cancer was 5.38 pM vs. 2.40 pM in those without cancer (p = 0.03). Limitation of FDG-PET/CT screening to patients with TF activity > 2.8 pM would improve the PPV to 37.5% and reduce the costs of a single cancer diagnosis from 20,711€ to 11,670€. FDG-PET/CT is feasible for the screening of occult cancer in patients with unprovoked VTE, showing high S and NPV. The addition of TF activity determination may be useful for patient selection.

Tumor necrosis factor-alpha inhibition reduces CXCL-8 levels but fails to prevent fibrin generation and does not improve outcome in a rabbit model of endotoxic shock.

The effects of a monoclonal antibody (mAb) to tumor necrosis factor-alpha (TNF-alpha) were examined in a rabbit model of endotoxic shock. Intravenous administration of lipopolysaccharide (100 microg/kg/hr) for 6 hours (n = 11) increased TNF-alpha levels. Fibrinogen was partially consumed, and fibrin deposits were seen in kidney and lungs at 24 hours. Mortality at 24 hours was 64%. Levels of interleukin-8 (aka CXCL-8) were notably increased. Mean arterial pressure (MAP) and leukocyte counts decreased, whereas creatinine levels were enhanced. The anti-TNF-alpha mAb (20 mg/kg i.v. bolus + 5 mg/kg/h i.v. for the first 90 minutes) (n = 10) efficiently inhibited the TNF-activity. Rabbits exhibited lower CXCL-8 levels; MAP improved, the decrease in leukocyte counts was partially prevented and creatinine levels were lower, but fibrinogen, fibrin deposits in kidneys and lungs and mortality, 55%, were similar to the LPS group. Rabbits that did not survive exhibited lower fibrinogen levels, more fibrin in kidneys and lungs and higher CXCL-8 and creatinine levels than survivors, while there were no differences in TNF-alpha, MAP and leukocytes. Thus, the inhibition of TNF-alpha, although beneficial through lowering CXCL-8 levels, is not enough to improve the outcome, which could be partly due to the inability to prevent the fibrin deposits formation in kidneys and lungs.

The endotoxin-induced plasminogen activator inhibitor-1 increase in rabbits is not tumor necrosis factor-alpha dependent and can occur in the absence of interleukin-1beta.

The plasminogen activator inhibitor-1 (PAI-1)-dependent fibrinolytic inhibition occurring in endotoxemia contributes to disseminated intravascular coagulation (DIC). Previous findings suggest that tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) are responsible for the increase in the level of PAI-1. These observations usually arose from mild endotoxemia models. We analyzed the effect of FR167653, an inhibitor of the TNF-alpha/IL-1beta production, on the PAI-1 levels in rabbits given endotoxin at a dose sufficient to induce DIC: the steep plasma PAI-1 increase was not attenuated by FR167653, in spite of achieving efficient inhibition of the TNF-alpha production. No IL-1beta was detected during endotoxemia. These results suggest that PAI-1 increase might be independent of TNF-alpha and IL-1beta. If these findings applied to humans, therapeutic intervention directing these cytokines would not be useful for the treatment of fibrinolysis in patients with severe sepsis.

Interleukin (IL)-8 and growth related oncogene-alpha in severe endotoxemia and the effects of a tumor necrosis factor-alpha/IL-1beta inhibitor on these chemokines.

FR167653 inhibits the production of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta, powerful inducers of CXC chemokines IL-8 and growth related oncogene (GRO)-alpha. The production of IL-8 and GRO-alpha was investigated and the effects of FR167653 were examined in a rabbit model of endotoxin shock. Male New Zealand rabbits were given endotoxin at a dose sufficient to induce DIC. Three groups of rabbits received FR167653 at different doses. TNF-alpha, IL-1beta, IL-8, and GRO-alpha levels were measured, several pathologic features were evaluated, and the results were compared with those obtained in control rabbits, which received only endotoxin. Endotoxin increased serum levels of IL-8 and GRO-alpha, which were associated with hypotension, renal dysfunction, and mortality, peaking at 4 h. FR167653 improved mortality, an event that was associated with decreased levels of not only TNF-alpha and IL-1beta but also IL-8 and GRO-alpha. TNF-alpha peaked at 2 h, at a time point before IL-8 and GRO-alpha reached their peak, and the TNF-alpha level was tightly correlated with that of IL-8 and GRO-alpha. Altogether, these data suggest the possible involvement of IL-8 and GRO-alpha in endotoxin shock, and FR167653 may foster a beneficial outcome in part by modulating the chemokines level by inhibiting TNF-alpha and IL-1beta.