Anti-HI can cause a severe delayed hemolytic transfusion reaction with hyperhemolysis in sickle cell disease patients.

BACKGROUND: Delayed hemolytic transfusion reaction (DHTR) is a life-threatening condition in sickle cell disease (SCD) patients that is frequently complicated by hyperhemolysis. Antibodies resulting from antigen disparity between donors of European ancestry and patients of African ancestry are common, but situations involving antibodies not classically of clinical significance are also encountered. Anti-HI is generally considered to be an innocuous naturally occurring antibody. STUDY DESIGN AND METHODS: We describe two cases of hyperhemolysis with anti-HI and provide details of the reported cases. RESULTS: Both SCD patients were polyimmunized and belonged to blood group B. They developed anti-HI that was reactive at 37°C, after the transfusion of group O red blood cell units matched for all known and produced antibodies classically considered to be clinically significant. Both patients developed DHTR with hyperhemolysis. In the first case, a pregnant woman, a second transfusion was unavoidable and the patient died from cardiac arrest. The state of the second patient improved without the need for further transfusion. CONCLUSION: Three other cases of DHTR with anti-HI have been described in the literature in SCD patients. The two additional cases reported here definitively demonstrate that anti-HI is dangerous in SCD patients. As a result, ABO-identical matching (including A1 status) must be considered in SCD patients with anti-HI.

A novel GYPB-A-B hybrid gene responsible for Ss and MN typing discrepancies.

BACKGROUND: Transfusion support of S-s- patients is very challenging but can now be alleviated by genotyping mutations in the GYPB gene to predict their U- or U+(var) phenotype. However, the phenotype predicted by genotyping does not always correspond to the observed phenotype of red blood cells (RBCs), which requires further investigation to avoid such a typing discrepancy in the future. In this study, we elucidated the case of an S-s- female patient of African origin who was predicted to be S+s- by our genotyping platform. STUDY DESIGN AND METHODS: Long-range polymerase chain reaction (PCR) amplification and extended Sanger sequencing were required. RESULTS: The Ss typing discrepancy in the proband resulted from a converted GYPB allele that encodes neither S nor s due to the replacement of Exon B4 of GYPB by the homologous Exon A4 of GYPA. In this novel GYPB-A-B hybrid gene, the GYPA segment actually starts just downstream of Exon B2, causing a MN typing discrepancy too. While the proband's RBCs were M+N-, the genotyping predicted the M+N+ phenotype. CONCLUSION: The reported GYPB-A-B hybrid gene constitutes a limitation for the accurate prediction of the MN and Ss phenotypes by current genotyping methods. A PCR assay was therefore developed to detect its presence.

RHD*DOL1 and RHD*DOL2 encode a partial D antigen and are in cis with the rare RHCE*ceBI allele in people of African descent.

BACKGROUND: Several studies showed in people of African descent the existence of a genetic linkage between RHD alleles encoding a variant D antigen and a given altered RHCE*ce allele. RHCE*ceBI is a rare allele encountered in people of African descent, that encodes a Hr- hr(S) - Rhce protein. Our study shows that RHCE*ceBI appears to be genetically linked to two very similar variant RHD alleles, RHD*DOL1 and RHD*DOL2, and demonstrates for the first time that DOL-2 is a partial D antigen. STUDY DESIGN AND METHODS: After finding out an individual with both RHCE*ceBI and RHD*DOL presumed to be in cis, we hypothesized a genetic linkage between those two genes. All individuals (n = 7) known to carry RHCE*ceBI in our laboratory, including the index case, were fully investigated at the serologic and molecular level. RESULTS: One individual with alloanti-D, being homozygous for RHCE*ceBI and RHD*DOL2, allowed us to confirm the genetic linkage between those two genes, as well as the partial D status of DOL-2. In the six RHCE*ceBI remaining individuals, three were found with RHD*DOL2 and 3 with RHD*DOL1, likely in cis. Three of them made an alloanti-D; one was DOL-1 and two were DOL-2. CONCLUSION: The rare RHCE*ceBI allele appears to be in cis either with RHD*DOL1 or with RHD*DOL2 in people of African descent. DOL-1 and DOL-2 must be considered as partial D antigens. We recommend a systematic search for RHD*DOL1 and RHD*DOL2 in people found to carry RHCE*ceBI and vice versa, especially in patients with sickle cell disease.

Survival response to B-cell receptor ligation is restricted to progressive chronic lymphocytic leukemia cells irrespective of Zap70 expression.

Despite very similar gene expression profiles, the clinical course of B-cell chronic lymphocytic leukemia (B-CLL) is heterogeneous. Immunoglobulin VH (IgVH) mutational status and expression of B-cell receptor (BCR) signaling mediators have been associated with disease progression. However, the consequences of BCR engagement on cell survival and evolution of the disease remain unclear. We show here that B-CLL cell survival is dependent on the threshold of BCR stimulation induced by immobilized antibody, in contrast to soluble anti-mu F(ab)'2 antibody, which leads to apoptosis. Measurement of metabolic activity and apoptotic response discriminated two subgroups. "Nonresponders" showed low metabolic activity and unmodified apoptotic response upon BCR stimulation. In contrast, "responders" exhibited increased metabolic activity and inhibition of spontaneous apoptosis. This survival advantage was associated to a BCR-dependent activation profile leading to induction of cyclin D2/cyclin-dependent kinase 4 (cdk4) expression and G1 cell cycle progression. The ability to respond to BCR ligation correlated with an unfavorable clinical course and allowed to define an additional group of patients among IgVH-mutated cases exhibiting a risk of progression. Remarkably, we show that Zap70 expression was neither mandatory nor sufficient to generate downstream survival signals and cyclin D2/cdk4 up-regulation. In conclusion, BCR engagement has a significant effect on B-CLL cell survival, activation, and G1 progression. Furthermore, our results provide new insights in the physiopathology of progressive IgVH-mutated cases.

Pure red-cell aplasia and antierythropoietin antibodies in patients treated with recombinant erythropoietin.

BACKGROUND: Within a period of three years, we identified 13 patients in whom pure red-cell aplasia developed during treatment with recombinant human erythropoietin (epoetin). We investigated whether there was an immunologic basis for the anemia in these patients. METHODS: Serum samples from the 13 patients with pure red-cell aplasia were tested for neutralizing antibodies that could inhibit erythroid-colony formation by normal bone marrow cells in vitro. The presence of antierythropoietin antibodies was identified by means of binding assays with the use of radiolabeled intact, deglycosylated, or denatured epoetin. RESULTS: Serum from all 13 patients blocked the formation of erythroid colonies by normal bone marrow cells. The inhibition was reversed by epoetin. Antibodies from 12 of the 13 patients bound only conformational epitopes in the protein moiety of epoetin; serum from the remaining patient bound to both conformational and linear epitopes in erythropoietin. In all the patients, the antibody titer slowly decreased after the discontinuation of treatment with epoetin. CONCLUSIONS: Neutralizing antierythropoietin antibodies and pure red-cell aplasia can develop in patients with the anemia of chronic renal failure during treatment with epoetin.

Deciphering leukemic B-cell chronic lymphoproliferative disorders.

Diagnosis of leukemic B-cell chronic lymphoproliferative disorders (B-CLPD) is a frequent challenge in hematology. In this multicentric study, we prospectively studied 165 new consecutive leukemic patients with B-CLPD selected on the basis of Royal Marsden Hospital scoring system < or =3. The primary aim of the study was to try to decipher the atypical cases and identify homogenous subgroups. Overall, morphological examination contributed to diagnosis in only 20% cases, all of them CD5 negative. Thirty additional cases were CD5 negative suggestive of leukemic marginal zone lymphoma in most cases. The significantly poorer survival of the 26 cyclin D1 positive cases justifies recommending its systematic determination among atypical B-CLPD. CD20 expression segregated clearly two subgroups among CD5 positive cyclin D1 negative B-CLPD. The 17 patients with the CD20 dim profile represent a homogeneous subgroup very close to typical B-cell chronic lymphocytic leukemia (B-CLL) on morphological, phenotypical and cytogenetical criteria. In contrast, the subgroup of 51 patients with a CD20 bright profile is heterogeneous. Their significantly lower p27 expression level suggest the presence of a proliferative component, underlying a more aggressive disease. Further genomic studies are warranted to establish their precise nature. These cases should not be included in the same therapeutic trials as B-CLL.