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Biomedical subjects

L E Silberstein

Publications and source records attributed to L E Silberstein.

At least 55 records · Page 3Linked to original sources
PubMed1993

Naturally occurring anti-i/I cold agglutinins may be encoded by different VH3 genes as well as the VH4.21 gene segment.

In the current study, we wished to determine if the V regions encoding the naturally occurring anti-i/I Cold Agglutinins (anti-i/I CA) differ from pathogenic anti-i/I CA that are exclusively encoded by the VH4.21 gene. After EBV transformation of B lymphocytes, we generated one anti-I secreting clone from each of two individuals; clone 4G (individual CM, PBL) and clone Sp1 (individual SC, spleen). Clone 4G expresses a VH3 gene sequence that is 92% homologous to the germline gene WHG26. Clone Sp1 also expresses a VH3 gene that is 98% homologous to the fetally rearranged M85/20P1 gene. Another clone, Sp2 (anti-i specificity), from individual SC is 98% homologous to the germline gene VH4.21. For correlation, we studied anti-i/I CA fractions purified from 15 normal sera and found no or relatively small amounts of 9G4 (VH4.21 related idiotype) reactive IgM. Five cold agglutinin fractions contained large amounts of VH3-encoded IgM (compared to pooled normal IgM) by virtue of their binding to modified protein Staph A (SPA), and absorption of three CA fractions with modified SPA specifically removed anti-i/I binding specificity entirely. Collectively, the data indicate that naturally occurring anti-i/I CA may be encoded to a large extent by non-VH4.21-related genes, and that the VH4.21 gene is not uniquely required for anti-i/I specificity.

Agglutinins↗
PubMed1992

Variable region gene analysis of an isotype-switched (IgA) variant of chronic lymphocytic leukemia.

Chronic lymphocytic leukemia of B-cell origin (B-CLL) is generally thought to arise by neoplastic transformation of B lymphocytes, which express CD5 and have features of an early stage of B-cell differentiation. To study isotype-switched B-CLL as a potentially more differentiated variant, we performed genetic and functional immunoglobulin (Ig) gene analysis in two cases of CD5+ B-CLL in which the peripheral blood mononuclear cells (PBMC) secreted predominantly IgA (CLL-249) or IgG (CLL-412) when stimulated with pokeweed mitogen in vitro. By cDNA sequencing and by studies of CLL-heterohybridomas, CLL-249 expresses the heavy chain constant region C alpha as anticipated, while CLL-412 expresses C mu, not C gamma. In CLL-249, the expressed VH gene is 98% homologous to VH26, a germline VH3 gene that occurs frequently in the fetal repertoire, and which has been associated with anti-DNA specificity. The VL gene of CLL-249 is a lambda VL gene for which the germline sequence is not known. In CLL-412, the VH gene is 100% homologous to the VH1 gene of a published anti-DNA antibody (21/28), and is probably a germline gene sequence; the VL gene is 100% homologous to 15AVKI, also a germline gene. The supernatant antibody of the CLL-412 heterohybridoma is an IgM-kappa, which reacts with ssDNA and cardiolipin. The CLL-249 heterohybridoma secreted IgA-lambda, which bound none of the antigens tested, a finding that may be related to amino acid differences from the probable germline V genes. The demonstration of an in vivo isotype-switched variant, such as CLL-249, suggests that B-CLL may be a heterogeneous group of clonal disorders, of which less common variants may have features of more differentiated B-cell stages, such as isotype switching.

Amino Acid Sequence↗
PubMed1992

Leukocyte reduction in blood component therapy.

PURPOSE: To review methods of preventing or minimizing the adverse effects associated with the transfusion of passenger leukocytes present in cellular blood components and to define groups of patients who are at risk for adverse effects. DATA SOURCES: English-language articles on transfusion medicine. STUDY SELECTION: Original reports describing the pathogenesis of leukocyte-induced adverse effects in transfusion recipients and the influence of leukocyte-reduced blood components on these effects. DATA EXTRACTION: Evaluation of the diagnosis, transfusion history, and treatment of the study patients; the methods and results of leukocyte reduction; and specific outcomes, including development of alloimmunization to leukocytes, febrile reactions to transfusion, and platelet refractoriness. DATA SYNTHESIS: Passenger leukocytes are the chief cause of alloimmunization to human leukocyte antigen (HLA) and leukocyte-specific antigens in transfusion recipients. Alloimmunization may result in febrile transfusion reactions, platelet refractoriness, and acute lung injury. Leukocytes are also the vector for transfusion-associated cytomegalovirus infection. Technologic advances in the leukocyte reduction of cellular blood components have made it possible to reduce the number of leukocytes to fewer than 10(7) per transfusion. Findings suggest that the use of leukocyte-reduced cellular blood components may minimize or prevent recurrent febrile reactions and alloimmunization to leukocyte antigens. Cytomegalovirus may not be transmitted by blood components containing fewer than 10(7) leukocytes. CONCLUSIONS: Leukocyte reduction in red blood cell and platelet transfusions using third-generation filters is indicated for selected patients who are likely to receive long-term transfusion support, to prevent recurrent febrile reactions and to prevent or delay alloimmunization to leukocyte antigens. Leukocyte-depleted transfusions may also be indicated to delay or prevent refractoriness to platelet transfusion.

Blood Component Transfusion↗
PubMed1992

Reducing the risk for transfusion-transmitted cytomegalovirus infection.

OBJECTIVE: To define the groups of patients at risk for transfusion-transmitted cytomegalovirus infection and to define the methods to reduce this risk. DATA SOURCES: English-language publications on transfusion medicine. STUDY SELECTION AND DATA EXTRACTION: Studies were selected that described cytomegalovirus infection in transfusion-dependent patients. Special attention was paid to reports that included observations about the prevalence and clinical manifestations of cytomegalovirus infection and recommendations for the prevention of infection. DATA SYNTHESIS: Some patients with impaired immune responses who have never been exposed to cytomegalovirus are at risk for transfusion-transmitted cytomegalovirus infection. This infection, which is associated with substantial morbidity and mortality, can be avoided by additional screening of blood donors or by special processing of components for transfusion. CONCLUSIONS: Transfusion products that are unlikely to transmit cytomegalovirus infection can be prepared by filtration to remove leukocytes or can be obtained by selecting donors who are seronegative for antibodies to cytomegalovirus. These products are indicated for certain groups of immunosuppressed patients, including pregnant women who are cytomegalovirus seronegative, premature infants of low birth weight who are born to cytomegalovirus-seronegative mothers, cytomegalovirus-seronegative recipients of allogeneic bone marrow transplants from cytomegalovirus-seronegative donors, and cytomegalovirus-seronegative patients with the acquired immunodeficiency syndrome (AIDS).

Cytomegalovirus Infections↗
PubMed1992

Idiotypic heterogeneity of VKIII autoantibodies to red blood cell antigens.

VKIII light (L) chains are commonly expressed by human autoantibodies with diverse binding specificities, including red blood cell antigens. To better understand the physiologic and pathologic expression of these L chain variable region genes, we have created a panel of murine monoclonal anti-idiotypic antibodies by immunization with a human lymphoblastoid B cell line that secretes an IgM VKIII autoantibody specific for the I red blood cell carbohydrate determinant. The binding specificities of these nine murine monoclonal antibodies, termed IV.1-IV.9, were evaluated against a large panel of monoclonal Ig proteins and compared to two previously well-characterized monoclonal anti-idiotypes, 6B6.6 and 17.109; these two anti-idiotypes have been shown to primarily identify VKIII rheumatoid factors derived from the kv328 (VKIIIa) and kv325 (VKIIIb) genes, respectively. In contrast, our anti-idiotypic antibodies identified (public) cross-reactive idiotypes present on many VKIII proteins that included both anti-erythrocyte and rheumatoid factor autoantibodies. Certain anti-idiotypic antibodies (IV.2 and IV.6) were restricted to VKIIIa L chains but differed from the 6B6.6 anti-idiotype by binding to a larger subset of VKIIIa proteins representing the products of at least two VKIIIa genes. One antibody of our panel (IV.5) recognized a private idiotope expressed only by the immunizing antibody. Using the panel of anti-idiotypic antibodies to evaluate erythrocyte autoantibodies with different serologic specificities, we found striking heterogeneity of L chain idiotype expression, even among known VKIII anti-i/I autoantibodies. These findings differ from the recently described structural and idiotypic conservation associated with the H chain of anti-i/I autoantibodies. From correlations of idiotypic reactivity with L chains of known sequence, it is postulated that the observed heterogeneity of L chain idiotype expression is due to differences in the genetic origin and/or somatic diversification of L chain variable region genes. Furthermore, subtle variability of L chain structure may contribute in part to the differences in fine binding specificity among anti-I and anti-i autoantibodies.

Agglutinins↗
PubMed1991

Structural basis of a conserved idiotope expressed by an autoreactive human B cell lymphoma. Evidence that a VH CDR3 mutation alters idiotypy and specificity.

Our laboratory has previously investigated the relationship of autoimmune disease and B cell neoplasia in a patient with a diffuse, well differentiated splenic B cell lymphoma and associated autoimmune hemolysis due to an anti-Pr2 antibody. EBV-immortalized B cell clones, established from this lymphoma, were shown to secrete the same pathologic anti-Pr2 antibody. The antiidiotypic mAb, RI.1, defined a private Id (IdRI.1) of the anti-Pr2 antibody that was related to the Ag-binding site and was expressed by both the lymphoma and derived cell lines. This unique Id was expressed by the majority of splenic tumor B cells and also was conserved over a period of 4 yr. In this report, the structural basis of IdRI.1 expression was investigated by analysis of Id- variants isolated by flow microfluorimetry using RI.1. Six Id- cell lines that secrete IgM kappa but lack Pr2 specificity were generated from an Id+ cell line, LS2. These lines were shown to be related to LS2 and the lymphoma by karyotype and by restriction fragment analysis of Ig gene rearrangements. Shared and unshared nucleotide substitutions in the VH and VL regions of the six independent clones were used to construct a genealogic tree relating the Id- clonal members to a common Id+ precursor. The tree illustrates that the base changes occurred sequentially, suggesting that they were introduced by somatic point mutation. Only one VH CDR3 bp difference from the LS2 nucleic acid sequence is common to all Id- sequences, resulting in an amino acid substitution of cysteine 108 to tyrosine. Taken together, these findings suggest that both the expression of IdRI.1 and Ag binding are affected by a single mutation localized to the D region of the anti-Pr2 antibody.

Amino Acid Sequence↗
PubMed1991

Variable region gene analysis of pathologic human autoantibodies to the related i and I red blood cell antigens.

To investigate the molecular basis of the autoimmune response to the related i and I carbohydrate antigens, we studied cold agglutinins (CA) from B-cell clones and from the peripheral circulation of patients with lymphoproliferative syndromes. Sequence analyses of expressed variable region genes indicate that both anti-i and anti-I specificities from B-cell clones from two patients are encoded by the VH4.21 or a very closely related VH4 heavy chain gene, whereas the expressed light chain genes differed. The anti-i-secreting B-cells express unmutated germline-encoded VH4.21 and VKI gene sequences. The VH region gene encoding anti-I has the closest homology (97%) to the VH4.21 germline gene and differs at the protein level by only three amino acids. In contrast, while the VL region gene encoding anti-I is most homologous (96%) to the VKIII, kv328 germline gene, there are seven amino acid differences due to nonrandom replacement mutations, which suggests a role for antigen-mediated selection in the anti-I response of this individual. These studies were extended by a structural survey of 20 additional serum CA using antipeptide antibodies specific for determinants in VH and VL regions. All anti-I and anti-i CA were shown to express VH4 heavy chains, and 14 of 17 CA expressed a previously described VH4 second hypervariable region determinant, termed VH4-HV2a. We also found that 13 of 14 anti-I CA used VKIII light chains, while the anti-i CA used light chains from at least three VL families. Taken together, the data show that anti-i and anti-I CA probably both derive from the VH4.21 gene (or a closely related gene). Furthermore, the restricted VH and different VL gene use in anti-i and anti-I CA may reflect the close structural relationship of the i and I antigens.

Autoantibodies↗
PubMed1991

The role of clonal selection in the pathogenesis of an autoreactive human B cell lymphoma.

To study the association of autoimmunity and human B cell neoplasia, we have established a model of a B cell lymphoma which expresses a pathogenic autoantibody of defined specificity. The Ig VH gene expressed in this neoplasm was analyzed longitudinally using clinical specimens taken from the splenic lymphoma (S) at diagnosis and from lymph node relapses 3 and 4 yr later (N3 and N4). Southern analysis and oligonucleotide hybridization experiments demonstrated that clonally related predominant and minor tumor cell populations were present in S at diagnosis, and that the minor population became the predominant population in the relapse specimens, N3 and N4. Although the Ig specificity and idiotype were the same at diagnosis and at both relapses, analysis of the expressed VH gene sequences showed 14 base changes between S and N3, and 2 further changes at N4. Little sequence heterogeneity was observed at each sampling time, indicating that the ongoing mutation frequency was low. The relevant germline precursor VH gene was determined from autologous germline DNA and compared to the expressed genes. Based on the pattern of shared and unshared mutations, we were able to establish the genealogic relationship of the germline VH gene and the expressed clonotypes of S, N3 and N4. Taken together, the findings from Southern blotting, oligonucleotide hybridization, and sequence analysis permit us to describe a molecular aspect of tumor progression, "clonotypic shift", wherein subpopulations of the malignant clone, marked by different V gene clonotypes, emerge and predominate at different time points in the evolution of the lymphoma. Furthermore, the sequential and nonrandom pattern of the VH mutations, correlated with the observed conservation of autospecificity and idiotype, implies that clonal selection may have influenced the pathogenesis of the lymphoma.

Amino Acid Sequence↗
PubMed1990

Guidelines for transfusion support in patients undergoing coronary artery bypass grafting. Transfusion Practices Committee of the American Association of Blood Banks.

We have reviewed the impact of evolving issues in coronary artery bypass grafting (CABG) on transfusion support for these patients. Issues include increased awareness of transfusion risks, reappraisal of traditional indicators triggering transfusion, and evolving alternatives to homologous blood transfusion such as autologous blood and pharmacologic therapy. These issues have been prompted by programs, such as the National Institutes of Health Consensus Conferences, to provide physicians with guidelines for appropriate use of blood components. However, evidence suggests that transfusion practice in coronary artery bypass grafting procedures remains variable and does not take into account the results of recently published clinical studies. We have therefore developed guidelines and recommendations for transfusion support in patients undergoing coronary artery bypass grafting. In summary, they are the following. 1. Institutions with coronary artery bypass grafting programs should establish a multidisciplinary approach to use a combination of interventions designed to minimize homologous blood exposure. 2. Prophylactic transfusion of plasma and platelets are of no benefit and therefore carry an unnecessary risk to the patient. 3. Special request products such as designated blood donation from first-degree relatives should not be used because of the risk of transfusion-associated graft versus host disease. 4. For support of intravascular volume, crystalloids or colloids should be used because they do not have the potential to transmit infection.

Algorithms↗
PubMed1989

Strategies for the review of transfusion practices.

The intent of this report is to familiarize health care professionals with the concept of effective quality assurance in regard to blood use. Although evaluation of the appropriateness of transfusion therapy is now required by the Joint Commission on Accreditation of Health Organizations, health care facilities have little experience with this aspect of professional quality assurance. To this end, the Committee on Transfusion Practices of the American Association of Blood Banks, in Arlington, Va, in this report has provided examples of indications and audit criteria for individual blood components and products and commented on areas of controversy surrounding their use. Audit criteria from different institutions may vary because of differences in local interpretation of the indication, different patient populations, and, in some instances, the availability of blood and laboratory services. Several approaches to the review of transfusion practices are discussed in relation to clinical settings and pertaining to particular blood components. It is evident from these examples that there will be an increased need for trained personnel to perform the initial review process as well as for physicians trained in transfusion medicine to oversee the transfusions and provide the necessary consultation.

Blood Banks↗
PubMed1989

Relationship of variable region genes expressed by a human B cell lymphoma secreting pathologic anti-Pr2 erythrocyte autoantibodies.

To study the biology of cold agglutinin disease we previously established EBV-transformed B cell clones isolated from a patient with splenic lymphoma of an early plasmacytic cell type and immune hemolysis due to an anti-Pr2 cold agglutinin. These clones had an aberrant chromosomal marker identical to the patient's B cell lymphoma and each secreted IgMk anti-Pr2 similar to the pathologic autoantibody in the serum of the patient. In this study, we have further investigated the Pr2-specific autoimmune response through nucleotide sequencing of VH and VL region genes. We have shown that the seven clones share the same VDJ/VJ gene segments and junctional elements confirming their clonal origin. The VH sequences were 88% homologous to a VHI germline gene while the VL sequences were 97% homologous to a VkIII germline gene. Only 4 somatic mutations (3 silent and 1 conservative) were found in greater than 5,000 bp sequenced, suggesting that a low mutation rate existed. Based on a tumor mass of 10(12) cells and a minimum of 40 divisions, we estimated the somatic mutation rate to be 4.45 x 10(-5) m/bp/d. This somatic mutation rate is similar to those estimated for acute lymphocytic leukemia (pre-B cell) and chronic lymphocytic leukemia (intermediate B cell), but significantly lower than the mutation frequency in follicular lymphomas (activated B cell). We propose that the difference in somatic mutation frequency of a B cell tumor may be related to the stage of B cell differentiation. In addition, the low mutation frequency observed in the Pr2-specific B cell tumor may also reflect, in part, selection by autoantigen to conserve sIg structure and specificity.

Agglutinins↗
PubMed1988

Comparative biochemical and genetic characterization of clonally related human B-cell lines secreting pathogenic anti-Pr2 cold agglutinins.

To study the biology of cold autoimmune hemolytic anemia, Epstein-Barr virus (EBV)-transformed B-cell clones were established from a patient with splenic lymphoma associated with immune hemolysis due to an anti-Pr2 cold autoantibody. Studies were performed comparing the cold autoantibody present in culture supernatants of these cell lines to the pathogenic cold autoantibodies present in the patient's plasma. Cytogenetic studies of splenic lymphocytes demonstrated an abnormal karyotype (51XX, +3, +9, +12, +13, +18). After EBV transformation, eight clones secreting IgM, kappa anti-Pr were isolated; each clone had the same abnormal karyotype as above. DNA isolated from the clones and spleen was analyzed by Southern blot hybridization with JH, C mu, and C kappa probes; identical gene rearrangements were seen in each case. Anti-Pr antibodies, isolated from culture supernatant and serum were compared by isoelectric focusing (IEF) and demonstrated similar banding patterns. Distinctive binding patterns, however, were observed in 2/8 clones, suggesting structural differences. Adsorption studies with red blood cells further showed that the observed IEF banding patterns were solely due to anti-Pr cold autoantibody. With a thin-layer chromatography method, the biochemical determinants recognized by the cold autoantibodies were defined as glycolipids containing Neu Ac alpha 2-3Gal beta 1-4Glc sequences. The data demonstrate that the autoantibodies of the EBV-transformed B-cell lines were similar to the pathogenic monoclonal serum autoantibody in both structure and specificity. These clonal cell lines may thus serve to further study the biology of human B-cell lymphomas with defined autoantibody specificity.

Adult↗
PubMed1987

Cold hemagglutinin disease associated with IgG cold-reactive antibody.

Six patients with chronic idiopathic cold hemagglutinin disease were studied whose serum cold agglutinin was not inactivated or was incompletely inactivated with the IgM-reducing agent dithiothreitol. In five of these patients, isolation of the antibodies revealed that two patients had predominantly IgG cold-reactive antibody, which was associated with smaller amounts of IgM in one patient and with IgA in the other; two patients had predominantly IgM cold agglutinin with lesser amounts of cold-reactive IgG; and one patient had an IgG cold agglutinin only. Both patients with predominantly IgG cold-reactive antibodies were treated with splenectomy and subsequently had a rise in more than hemoglobin levels that has been maintained for over 36 months without additional therapy. Two of the other three patients were treated with glucocorticoids only and responded similarly. These data indicate that a subset of patients with cold hemagglutinin disease have IgG cold-reactive antibodies. In contrast to patients with typical cold agglutinin disease, this subset appears responsive to glucocorticoids and splenectomy.

Adolescent↗
PubMed1987

Efficacy of intensive plasmapheresis in thrombotic thrombocytopenic purpura.

Forty-one patients with thrombotic thrombocytopenic purpura were treated at the Hospital of the University of Pennsylvania, Philadelphia, between 1975 and 1985. Initially, early splenectomy was performed. However, since 1981, more intensive plasma exchange therapy (increase in frequency and size of exchange) has been used as the primary modality of treatment for this disorder. A reduction of the mortality rate over time has been observed. For the period 1975 to 1980, the mortality rate was 41% (seven of 17). In contrast, for the period 1981 to 1985, the mortality rate decreased to 17% (four of 24). These observations support the concept that the initial management of thrombotic thrombocytopenic purpura with intensive daily plasma exchange is associated with improved survival. The role of platelet inhibitors and corticosteroids needs yet to be defined.

Adrenal Cortex Hormones↗