ALBERT

Beschreibung: Autologous stem cell transplantation has become an important therapy in multiple myeloma (MM). To develop adequate autograft purging methods, it is necessary to determine whether antigens expressed on early hematopoietic progenitors exist on malignant cells. The Ig heavy chain produced by the MM cells shows evidence of prior somatic mutation without intraclonal diversity. As a result, this sequence can be used as a specific marker to detect all members of the malignant clone. The Ig heavy chain sequence expressed by the MM cells was obtained in five patients with advanced disease. Patient specific oligonucleotide primers were designed based on the complementarity determining regions (CDR) of each MM Ig sequence and used to amplify DNA by polymerase chain reaction for the detection of malignant cells. A highly purified collection of CD34+ cells was obtained after passage of the initial bone marrow cells through an immunoadsorption column and fluorescence- activated cell sorting. Despite an assay sensitivity of 1 tumor cell in 2,500 to 44,000 normal cells, none of the CD34+ samples showed product with the myeloma-specific CDR primers. Therefore, positive selection for cells bearing this antigen should yield a tumor-free autograft capable of providing hematopoietic recovery after myeloablative chemotherapy.

Beschreibung: Unrelated donor marrow transplantation was undertaken in eight infants with severe combined immunodeficiency (SCID) and two children each with Wiskott-Aldrich syndrome (WAS) and Chediak-Higashi syndrome (CHS) who did not have histocompatible siblings. Donors for three patients were phenotypically matched at all HLA-A, B, Dr, and Dw loci, whereas nine donors were mismatched from the recipients at one of the HLA-A or B loci but phenotypically identical at evaluable D loci. All but one patient received conditioning chemotherapy and/or radiotherapy before infusion of donor marrow, which was not T-cell depleted. Prophylaxis for graft-versus-host disease (GVHD) consisted of methotrexate and prednisone combined with either cyclosporine A (six patients), antithymocyte globulin (five patients), or anti-CD5 ricin A chain immunotoxin (one patient). All patients engrafted with donor cells, and only 4 of 12 experienced any GVHD (1 of 8 SCID, 1 of 2 WAS, 2 of 2 CHS). Two children who developed grade II and two who developed grade III GVHD were successfully treated and all are now alive, off immuno- suppressive therapy, with no evidence of chronic GVHD greater than 18 months after transplant. Ten patients are alive with excellent immunoreconstitution greater than or equal to 1 year to greater than or equal to 3 years after transplant; actuarial survival is predicted to be 83% with a median follow-up of 2 years. Two children with SCID succumbed to pre-existing opportunistic infection early posttransplant. We conclude that closely matched unrelated donor bone marrow transplantation can correct congenital immunodeficiencies including variants of SCID, WAS, and CHS, with an acceptably low incidence of transplant-related complications, principally GVHD.

Beschreibung: Three Rh-related cDNAs have been isolated from a human bone marrow cDNA library and by polymerase chain reaction (PCR) amplification of human bone marrow and erythroblast mRNAs. They potentially encode a family of Rh protein isoforms that exhibit several unexpected structural properties as compared with the Rh polypeptide encoded by the cDNA clone identified previously. These modifications include several peptide deletions, the predicted alteration of Rh protein topology within the cell membrane, variations in the number and surface exposition of cysteine residues, and the generation of new C-terminal polypeptide segments caused by frameshift mutations. The four Rh mRNAs now described correspond to different splicing isoforms transcribed from the same Rh gene, and all exist in the same cell lineage (erythroid). Moreover, PCR experiments indicated that at least three of these RNA species exist in reticulocytes from donors with different commonly expressed Rh phenotypes. Although the translated proteins have not yet been characterized, these results suggest that the two genes at the RH locus may direct the synthesis of several protein species possibly corresponding to different Rh antigenic variants.

Beschreibung: Red blood cell deficiency of Rh proteins is associated with morphologic and functional abnormalities of erythrocytes and with a chronic hemolytic anemia of varying severity. Rh-deficiency may be the result of homozygosity either for a silent allele at the RH locus (Rhnull amorph type) or for a recessive inhibitor gene(s) at an autosomal locus unlinked to RH locus (Rhnull regulator and Rhmod). In this report, we investigated the RH locus structure of Rh-deficient individuals by Southern analysis using cDNA and exon-specific probes deduced from the recent cloning of Rh genes (CcEe and D). As expected from family studies indicating that Rhmod and Rhnull regulator individuals are unable to express Rh antigens but are able to convey functional Rh genes from one generation to another, no alteration of the Rh genes was detected in these variants. Although Rhnull of the amorph type arose by inheritance of a pair of silent alleles at the RH locus, the general organization of the unique CcEe gene in the genome of the particular individual under examination was apparently normal and indistinguishable from a Rh-negative chromosome. More surprisingly, no mutation could be detected by sequencing the polymerase chain reaction (PCR)-amplified reticulocyte mRNAs, suggesting that the RH locus of this patient might be altered in its transcriptional activity. Through hybridization with exon-specific probes, we were also able to determine the zygosity for the D gene in DNA samples from individuals of known genotypes; using this approach, we found that Rhnull regulator variants could be either of the DD, Dd, or dd genotypes. These findings suggest that the postulated inhibitor gene(s) can negatively suppress the RH locus expression from chromosomes carrying either one or two of the Rh genes.

Beschreibung: Mice homozygous for the scid (severe combined immunodeficiency) mutation are generally unable to produce B lymphocytes, a condition attributed to defective rearrangement of immunoglobulin genes in precursor B cells. Some early B-lineage cells are present in the bone marrow (BM), however. In scid mice, we defined three subsets of early progenitor B cells lacking mu heavy chains (pro-B cells) based on the expression of terminal deoxynucleotidyl transferase (TdT) and B220 glycoprotein: (a) early pro-B cells (TdT+B220-), (b) intermediate pro-B cells (TdT+B220+), and (c) late pro-B cells (TdT-B220+). Double immunofluorescence labeling of BM cell suspensions has shown normal numbers of early and intermediate pro-B cells, substantially reduced numbers of late pro-B cells, and an absence of pre-B cells and B cells. Early and intermediate pro-B cells accumulated in metaphase in near- normal numbers after intraperitoneal (IP) vincristine administration. B220+ pro-B cells have been localized in BM sections by the binding of intravenously (IV) administered 125I monoclonal antibody (MoAb) 14.8, detected by light and electron microscope radioautography. Many B220+ cells were located peripherally in the bone-lining cell layers associated with stromal reticular cells. More centrally located B220+ cells were frequently associated with macrophages containing prominent cytoplasmic inclusions. Occasional B220+ cells were present in venous sinusoids. These results demonstrate that many pro-B cells in scid mice occupy microenvironments in the BM near the surrounding bone. The pro-B cells maintain normal rates of production during stages of presumptive mu heavy-chain gene rearrangement, apparently unaffected by the absence of a mature B cell pool. Nearly all defective cells then abort at the late pro-B cell stage and are deleted, apparently by macrophages. The findings contribute to models of in vivo differentiation, regulation, localization, and selection of early B-lineage cells in the BM.

Beschreibung: Homozygous mutant rats at the newly found white spotting (Ws) locus were anemic and deficient in mast cells and melanocytes. Because the phenotype of Ws/Ws rats resembled the phenotype of mice possessing a double-gene dose of mutant alleles at the W locus and because the c-kit gene was mapped at the W locus of mice, we characterized the c-kit gene of Ws/Ws rats. The authentic sequence of the rat c-kit cDNA was determined by using a cDNA library prepared from the hippocampus of Sprague-Dawley rats. The c-kit cDNA of Ws/Ws and normal (+/+) control rats was obtained by reverse transcriptase modification of the polymerase chain reaction. When compared with the authentic sequence, a deletion of 12 bases was found in the c-kit cDNA of Ws/Ws rats. This change was shown to be a result of the deletion of the genomic DNA. Four amino acids encoded by the deleted 12 bases (ie, Val-Lys-Gly-Asn) were located at two amino acids downstream from the tyrosine autophosphorylation site in the c-kit kinase and were conserved not only in mouse and human c-kit kinases but also in mouse and human c-fms kinases (ie, receptors of colony-stimulating factor-1). Taken together, the Ws/Ws rat is the first characterized mutant of the c-kit gene in an animal species other than the mouse.

Beschreibung: Inbred Carworth Farms Nelson (CFN) congenitally hyperlipidemic rats had significantly shorter coagulation and prothrombin times and higher levels of coagulation factors, II, V, VII, VIII, and X than did controls. Conversely, congenitally hypolipidemic rats of the same strain had significantly longer coagulation and prothrombin times and lower levels of factors II, V, VII, X and XII and of blood platelets than did controls. A loop-shaped polyethylene cannula was inserted into the aorta to assess the potential for thrombosis. The hyperlipidemic group obstructed this significantly faster and the hypolipidemic group slower than did the controls. Normal CFN rats made hypertensive by unilateral renal artery clip developed hypertension together with significantly elevated serum cholesterol and factor VII and X levels. Rhesus monkeys with diet-induced hyperlipidemia showed shorter prothrombin times and higher factor X levels than did controls on normal diet. By selective breeding, two groups of squirrel monkeys were obtained. Both groups had similar serum cholesterol levels on a normal diet but one group (hyperresponders) showed higher serum cholesterol levels on a cholesterol-containing diet than did the other (hyporesponder) group. Both groups showed significantly elevated levels of factors II, V, VII, IX and X on a cholesterol-containing diet. There was good correlation between the levels of many coagulation factors and serum cholesterol in both rats and monkeys. If thrombosis is important in the genesis of atherosclerosis, these findings could indicate that elevation of plasma lipids may play a role, via the coagulation pathway, in the production of human vascular disease.

Beschreibung: The effect of differences in G gamma and A gamma fractions of fetal hemoglobin (HbF) on the kinetics of polymerization of HbS-HbF mixtures was studied. We also examined their effect on oxygen affinity, surface hydrophobicity, mechanical stability, and solubility of HbF. Differences in G gamma:A gamma ratio did not affect the polymerization of mixtures of HbF and HbS, suggesting that the inhibitory effect of HbF on the polymerization of HbS is independent of the G gamma:A gamma ratio of HbF and is totally dependent on the fraction of HbF in the mixture. The oxygen equilibrium curve of HbF was not affected by differences in the ratios of G gamma and A gamma in HbF. In contrast, surface hydrophobicity, mechanical stability, and solubility of HbF were affected by differences in the G gamma:A gamma ratio. The higher the G gamma:A gamma ratio, the smaller the elution volume on a TSK Gel SW hydrophobic column in high phosphate buffer. The mechanical stability of HbF was also dependent on the ratio of G gamma:A gamma; stability was greater at higher fractions of A gamma. Differences in the G gamma:A gamma ratio also affected solubility of HbF: HbF containing the higher fraction of G gamma was the more soluble. These data indicate that although alanine at the 136th position of the gamma chains has a stronger surface hydrophobicity than does glycine, this difference does not affect either the polymerization of HbS or the oxygen affinity of HbF.

Beschreibung: Homozygous mutant rats at the newly found white spotting (Ws) locus were anemic and deficient in mast cells and melanocytes. Because the phenotype of Ws/Ws rats resembled the phenotype of mice possessing a double-gene dose of mutant alleles at the W locus and because the c-kit gene was mapped at the W locus of mice, we characterized the c-kit gene of Ws/Ws rats. The authentic sequence of the rat c-kit cDNA was determined by using a cDNA library prepared from the hippocampus of Sprague-Dawley rats. The c-kit cDNA of Ws/Ws and normal (+/+) control rats was obtained by reverse transcriptase modification of the polymerase chain reaction. When compared with the authentic sequence, a deletion of 12 bases was found in the c-kit cDNA of Ws/Ws rats. This change was shown to be a result of the deletion of the genomic DNA. Four amino acids encoded by the deleted 12 bases (ie, Val-Lys-Gly-Asn) were located at two amino acids downstream from the tyrosine autophosphorylation site in the c-kit kinase and were conserved not only in mouse and human c-kit kinases but also in mouse and human c-fms kinases (ie, receptors of colony-stimulating factor-1). Taken together, the Ws/Ws rat is the first characterized mutant of the c-kit gene in an animal species other than the mouse.