Erythropoietin and inhibitors of in vitro erythropoiesis in the development of anemia in children with renal disease

The relative roles of erythropoietin and potential inhibitors of erythropoiesis in the development of anemia in children with renal disease have been studied. Thirty-five children with renal disease of varied origins and severity were compared with 30 children with anemia of similar severity and with normal renal function. Serum erythropoietin was measured by radioimmunoassay; erythroid (CFU-E) and granulocytic (CFU-GM) progenitor cell growth were assessed in fetal mouse liver cell and normal human bone marrow cell cultures, respectively. The degree of serum inhibition of in vitro CFU-E growth in children with renal disease correlated with both creatinine clearance (r = 0.59, P less than 0.001) and hematocrit level (r = 0.55, P less than 0.005). Serum from children with renal disease inhibited in vitro CFU-E growth in a dose-related manner. Normal serum did not inhibit CFU-E growth in culture. The mean serum erythropoietin concentration was significantly (P less than 0.025) higher in children with anemia of renal disease (32.4 +/- 2.4 mU/ml) in comparison with serum values in normal children (19.6 +/- 1.5 mU/ml), but serum erythropoietin levels did not correlate with hematocrit level, creatinine clearance, or serum inhibition of in vitro erythropoiesis. In contrast, children with anemia and normal renal function showed a significant (P less than 0.001) linear increase in serum erythropoietin concentration (range 28.7 to 327 mU/ml), increased reticulocyte count, and stimulation of CFU-E formation with decreasing hematocrit levels. Coincubation of human urinary erythropoietin in the presence of serum from patients with uremia revealed markedly less immunoreactivity in the radioimmunoassay and less biologic activity in the fetal mouse liver CFU-E assay for erythropoietin than when erythropoietin was incubated with normal human serum, suggesting some alteration of erythropoietin in the presence of uremic serum, which reduced both the immunologic and biologic activity of erythropoietin. Normal and uremic sera inhibited CFU-GM growth to the same degree in comparison with controls. In conclusion, relative erythropoietin deficiency, direct alteration in the biologic activity of erythropoietin by uremic toxins, and serum inhibition of erythroid progenitor cells in the bone marrow are probably important factors in the pathogenesis of anemia in children with renal disease.     

High anti‐HLA response in women exposed to intrauterine transfusions for severe alloimmune hemolytic disease is associated with mother–child HLA triplet mismatches,high anti‐D titer,and new red blood cell antibody formation

BACKGROUND: Women whose fetuses were treated with intrauterine transfusions (IUTs) for alloimmune hemolytic disease are high responders to red blood cell (RBC) antigens. We investigated the risk for HLA alloimmunization. STUDY DESIGN AND METHODS: Women and their children treated with IUT between 1987 and 2008 were included. Participants were HLA antigen typed and studied for the prevalence of HLA antibodies compared to age‐matched parous nontransfused blood donors. Anti‐D titer, the formation of new RBC antibodies after IUT, and the degree of fetomaternal HLA mismatches on HLA antibody formation and/or persistence were analyzed. RESULTS: A higher prevalence of HLA Class I antibodies was observed in these women compared to controls (41% vs. 23%). Both a higher anti‐D titer (>8000) and formation of new RBC antibodies after IUT were associated with increased HLA immunization. HLA antibody formation was associated with the number of fetomaternal triplet epitope mismatches. Antigens within HLA‐Bw4, HLA‐B35/51/52/53/18/78‐complex and A1/A9, were higher and mismatches within HLA‐C were less immunogenic than expected. HLA antibodies against the IUT‐treated fetus were more persistent than other antibodies. CONCLUSION: Women whose fetuses were treated with IUT had a high risk of developing and maintain fetal‐specific HLA Class I antibodies. Factors associated with increased HLA immunization were a higher amount of fetomaternal HLA triplet mismatches, higher anti‐D titer, and additional RBC antibody formation. We presume that the induction of HLA Class I antibodies is the result of increased fetomaternal hemorrhage during IUT, eliciting antibodies in women with an increased susceptibility to alloimmunization.     

Behavioural disturbance requiring medical referral: A case of anti‐N‐methyl‐D‐aspartate receptor encephalitis in the emergency department

A 17‐year‐old woman presented to the ED with behavioural disturbance and psychotic features. Brief dystonic jerks were noted so she was referred to the medical team. A diagnosis of anti‐N‐methyl‐D‐aspartate receptor encephalitis was made. Immunotherapy was instituted early and the clinical outcome was excellent. It is important to consider this condition in young women presenting with acute behavioural or psychotic symptoms.     

Life‐threatening hemolytic anemia due to an autoanti‐Pr cold agglutinin: evidence that glycophorin A antibodies may induce lipid bilayer exposure and cation permeability independent of agglutination

BACKGROUND: The hemoglobin of a 29‐year‐old man fell below 35 g/L over 5 days, despite 14 units of red blood cells (RBCs), due to an anti‐Pr cold agglutinin (CA). His hemolytic anemia necessitated respiratory support in intensive care for 4 weeks. STUDY DESIGN AND METHODS: The hemolysis was investigated by the effects on blood group–compatible RBCs of this anti‐Pr and an anti‐I CA and of a rabbit anti‐human glycophorin A (GPA) immunoglobulin G (IgG) antibody on Ca²⁺ permeability and of phosphatidylethanolamine (PE) exposure. 1) The anti‐Pr CA (in a plasmapheresis product from the patient) was absorbed and eluted from RBC ghosts and its immunophenotype was determined by agarose electrophoresis and immunofixation. 2) Ca²⁺ permeability was measured by the response of Fluo‐3–labeled RBCs to addition of external Ca²⁺. 3) Exposed PE was measured with streptavidin‐labeled biotinylated peptide Ro 09‐0198 (cinnamycin). RESULTS: 1) The patient's anti‐Pr CA was a polyclonal IgG. 2) The anti‐Pr and the rabbit anti‐human glycophorin IgG, but not an anti‐I CA, rapidly increased Ca²⁺‐dependent fluorescence upon addition of external Ca²⁺ in a fraction (15%‐25%) of RBCs that also became positive for cinnamycin. 3) Trypsin treatment of RBCs reduced the Ca²⁺ influx due to the anti‐Pr IgG, but neither trypsin nor neuraminidase changed the responses to the rabbit anti‐human GPA IgG. CONCLUSIONS: The anti‐Pr CA and rabbit anti‐human GPA increased exposure of PE and increased membrane Ca²⁺ permeability that may have caused hemolysis. The difference in the responses to these antibodies to enzyme treatment of RBCs suggests that they react with different epitopes on GPA.