Differential usage of an autoantibody-associated VH gene, VH4-21, by human B-cell tumors

Inflammatory myopathies and lymphoma

The inflammatory myopathies comprise a group of immune-mediated muscle diseases. Lymphoma is a term for a variety of lymphatic system malignancies. Autoimmune diseases and lymphoproliferative malignancies share a complex bidirectional relationship. A causal relationship between inflammatory mypathies and lymphoma has not been established. The diagnosis/treatment of inflammatory myopathy usually precedes the detection/diagnosis of lymphoma. Immune system dysregulation presumably underlies the evolution of lymphoma in patients with inflammatory myopathies. Inflammatory activity with chronic B-cell activation and/or antigen stimulation is deemed the major risk factor for lymphoma in patients with autoimmunity. A "paraneoplastic" phenomenon or the effects of immunosuppressive therapy may be alternative immune-based mechanisms. In chronic lymphocytic leukemia immune system disturbance rarely results in non-hematological autoimmune disease, including inflammatory myopathies.

B lymphocytes in systemic lupus erythematosus: lessons from therapy targeting B cells

Systemic lupus erythematosus (SLE) is a complex disease characterizedby numerous autoantibodies and clinical involvement in multiple organ systems. Autoantibodies are usually present in serum for years before the onset of clinical disease. Autoimmunity begins with a limited number of autoantibodiesand evolves to become progressivelymore diverse. Eventually clinical disease ensues. The immunological events triggering the onset of clinical manifestations have not yet been defined. While undoubtedly T cells and dendritic cells appear to play major roles in SLE, a central role for B cells in the pathogenesis of this disease has been brought to the fore in the last few years by work performed both in mice and humans by multiple laboratories.As a result, there is little doubt about the importance of B cells in the development of SLE. Yet much remains to be learned about their role in the ongoing disease process and the merit of targeting B cells for the treatment of SLE. This article will review the role of B cells in human SLE as well as the currently available data on the treatment of SLE by depleting B cells with anti-CD20 (rituximab).

[Clinical profile of autoimmune hemolytic anemia with monoclonal gammopathy IgMκ]

目的

探讨伴单克隆免疫球蛋白Mκ（IgMκ）血症的自身免疫性溶血性贫血（AIHA）临床特征。

方法

回顾性分析85例AIHA患者临床资料，观察伴单克隆IgMκ的AIHA患者一般临床特征、实验室检查特点及转归。

结果

85例AIHA患者中12例（14.1%）单克隆IgM κ阳性，其中4例温抗体型AIHA, 8例冷凝集素综合征（CAS）。4例温抗体型AIHA患者均为原发病例，免疫表型未见异常；8例CAS患者中，4例继发于小B细胞淋巴瘤，4例为原发CAS，免疫表型未见异常。4例温抗体型AIHA患者中2例TCR重排阳性；8例CAS患者中6例IgH重排阳性，1例TCR/IgH重排均阳性。4例温抗体型AIHA患者均给予糖皮质激素治疗，3例达完全缓解，1例部分缓解。8例CAS患者中3例给予小剂量利妥昔单抗治疗，2例部分缓解，1例无效；2例给予COP（环磷酰胺、长春新碱、甲泼尼龙）方案化疗，1例部分缓解，1例无效；2例HGB正常患者给予保暖对症治疗；1例院外行脾脏切除术，术后死于感染。

结论

CAS常伴有单克隆IgMκ，而温抗体型AIHA伴单克隆IgMκ较少见。

Lymphoma-associated dysimmune polyneuropathies

Lymphoma consists of a variety of malignancies of lymphocyte origin. A spectrum of clinical peripheral neuropathy syndromes with different disease mechanisms occurs in about 5% of lymphoma patients. There exists a complex inter-relationship between lymphoproliferative malignancies and autoimmunity. An imbalance in the regulation of the immune system presumably underlies various immune-mediated neuropathies in patients with lymphoma. This article reviews lymphoma and more-or-less well-defined dysimmune neuropathy subgroups that are caused by humoral and/or cell-mediated immune disease mechanisms directed against known or undetermined peripheral nerve antigens.

Molecular determinants of humoral immune specificity for the occupational allergen, methylene diphenyl diisocyanate

Methylene diphenyl diisocyanate (MDI), a low molecular weight chemical important for producing polyurethane foam, coatings, and elastomers is a major cause of occupational asthma, however, mechanisms of disease pathogenesis remain poorly understood. This study characterizes the rearranged germline and hypervariable region cDNA of new anti-MDI secreting hybridomas derived from mice immunized with MDI-conjugated to autologous serum proteins. Six IgG1 secreting clones were identified in initial screening ELISAs, based on differential binding to MDI conjugated human albumin vs. mock exposed albumin. The mAbs secreted by the hybridomas also recognized MDI conjugated to other model proteins (e.g. ovalbumin, transferrin), but did not bind unconjugated proteins, or protein conjugates prepared with other isocyanates (e.g. TDI, HDI). The mAbs displayed MDI-dose dependent binding in ELISA and Western blot, and exhibited varying degrees of cross-competition, suggesting differences in epitope specificity. The cDNA encoding the monoclonal antibodies reveal clonal differences in the CDR3 regions, germline gene usage, and patterns of somatic hypermutation related to epitope specificity. Together, the data provide new insight into the molecular determinants of humoral MDI specificity, and characterize anti-MDI IgG1 mAbs that may be developed into useful diagnostic reagents.

Autoimmune hemolytic anemias, Evans' syndromes, and pure red cell aplasia in non-Hodgkin lymphomas

We analyzed 108 cases of non-CLL non-Hodgkin lymphoma (NHL) associated with autoimmune hemolytic anemia (AIHA) (+/- pure red cell aplasia (PRCA)) or Evans' syndrome. The analysis was based on cases reported in the literature, which were retrieved by means of Pubmed and Medline searches and of an original series of 121 patients with NHL as well as reference lists of papers in the field. The number of cases in various NHL subtypes was small (n = 6-25). Nevertheless, interesting and sometimes unexpected differences in sex prevalence, temporal relationship between onset of lymphoma and AIHA, stage of lymphoma, relative frequency of warm antibody-AIHA (WA-AIHA) and cold antibody (CA-AIHA), association with PRCA and response of AIHA to treatments were noted for various lymphoma entities. WA-AIHA was more frequent in B-cell lymphomas, while CA-AIHA and PRCA predominantly occurred in T-cell lymphomas. Anti-lymphoma treatment seemed to be more effective against AIHA than conventional therapy with steroids or immunoglobulin. Although generated by a literature survey, this compilation of data indicates a complex relation of lymphoma and AIHA and warrants more attention and specific studies.

[Auto-immune manifestations in Non-Hodgkin's lymphoma]

PURPOSE

A wide spectrum of auto-immune manifestations is frequently reported in non-Hodgkin's lymphoma (NHL). The purpose of the review is to describe the immune manifestations observed in NHL, according to their histological subtype and to discuss the current physiopathological hypothesis with their therapeutic relevance.

CURRENT KNOWLEDGE AND KEY POINTS

Most of the organs can be targeted by an immune process due to the lymphoproliferative disease: they include skin diseases (paraneoplastic pemphigus, vasculitis, urticaria, acrosyndromes), peripheral and central nervous system involvement (polyneuropathy, multifocal neuropathy), haematological manifestations (immune cytopenia, acquired bleeding disorders), rheumatologic diseases (arthritis, systemic vasculitis, myositis) and renal lesion (cryoglobulinemia, glomerulopathies). A higher prevalence of autoantibodies, such as antinuclear antibodies, Antiphospholipid antibodies, or endomysium antibodies, is observed in NHL but usually without clinical manifestations. In B-cell NHL, clinical and biological immune manifestations are more frequently observed in indolent lymphoma than in aggressive NHL. In T-cell NHL, immune manifestations are frequent and polymorphous, preceding usually the diagnosis of lymphoma. The prognosis value of the immune manifestations in NHL is unclear. Immune manifestations can be also be related to the treatment procedure, including fludarabine, Interferon, autograft or Rituximab. The physiopathology of the immune manifestations may involve auto-antibodies production by natural CD5+ autoreactive B-cell from which is issue the proliferation, a lost of immune tolerance, an abnormality in the Fas/Fas Ligand pathway or a chronic antigenic stimulation.

FUTURE PROSPECTS AND PROJECTS

As observed in T-cell lymphoma cases, immunosuppressive treatment can control both immune manifestations and lymphoproliferation, suggesting that lymphoma and auto-immunity may be the two aspects of the same process. The monoclonal antibody anti-CD20 (rituximab), able to suppress the tumoral cells and change the B-cell repertoire is the most promising treatment to cure immune disorders related to NHL. So far, rituximab has been successfully used in mixed cryoglobulinemia and cold agglutinins secondary to NHL.

Primary diffuse large B-cell lymphomas of the central nervous system are targeted by aberrant somatic hypermutation

We have addressed whether aberrant ongoing hypermutation can be detected in the proto-oncogenes PIM1, c-MYC, RhoH/TTF, PAX5, and the tumor-suppressor gene CD95 in primary central nervous system lymphomas (PCNSLs) derived from immunocompetent HIV-negative patients. Nine of 10 PCNSLs analyzed harbored somatic mutations in the PIM1, c-MYC, RhoH/TTF, and PAX5 genes, but not in the CD95 gene, with 8 tumors carrying alterations in at least 2 of these genes. Furthermore, ongoing aberrant mutation was evidenced in a subset of PCNSLs (2 of 3). Although most of the mutations corresponded to base pair substitutions, deletions were also present. The mean mutation frequency was approximately 60-fold lower for these genes compared with the values obtained for immunoglobulin genes in PCNSL. They were increased 2- to 5-fold compared with extracerebral diffuse large B-cell lymphoma (DLBCL). In summary, our data demonstrate aberrant somatic hypermutations at high frequency in the PIM1, PAX5, RhoH/TTF, and c-MYC genes in most PCNSLs. These findings may indicate a pathogenic role for aberrant somatic hypermutation in PCNSL development. In contrast, although mutations were detected in exon 9 of the CD95 gene, the lack of mutations in the 5′ region provides no evidence for the CD95 gene as a target for aberrant somatic mutation.

The occurrence and significance of V gene mutations in B cell-derived human malignancy

The classification of B cell tumors has relevance for refining and improving clinical strategies. However, consensus has been difficult to establish, and although a scheme is now available, objective criteria are desirable. Genetic technology will underpin and extend current knowledge, and it is certain to reveal further subdivisions of current tumor categories. The Ig variable region genes of B cell tumors present a considerable asset for this area of investigation. The unique sequences carried in neoplastic B cells are easily isolated and sequenced. In addition to acting as clone-specific markers of each tumor, they indicate where the cell has come from and track its history following transformation. There is emerging clinical value in knowing whether the cell of origin has encountered antigen and has moved from the naive compartment to the germinal center, where somatic mutation is activated. This is amply illustrated by the subdivision of chronic lymphocytic leukemia into two subsets, unmutated or mutated, each with very different prognosis. Other tumors may be subdivided in a similar way. Microarray technology is developing rapidly to probe gene expression and to further divide tumor categories. All these genetic analyses will provide objective data to enhance both our understanding of B cell tumors and our ability to treat them.

Immunoglobulin variable region structure and B-cell malignancies

The enormous diversity of immunoglobulin (Ig) variable (V) gene sequences encoding the antibody repertoire are formed by the somatic recombination of relatively few genetic elements. In B-lineage malignancies, Ig gene rearrangements have been widely used for determining clonality and cell origin. The recent development of rapid cloning and sequencing techniques has resulted in a substantial accumulation of IgV region sequences at various stages of B-cell development and has revealed stage-specific trends in the use of V, diversity, joining genes, the degree of noncoding nucleotide addition, and the rate of somatic mutations. Furthermore, sequences from B-lineage malignant cells nearly reflect the characteristics of the normal counterpart at each respective stage of development. Alternatively, from the IgV region structure of the malignant cells, it is possible to speculate at which stage of B-cell development the cells were transformed. As the complete nucleotide sequences of the human Ig heavy and Ig light V region loci have now been determined, the study of Ig genetics has entered into the super-information era.

Analysis of the expressed immunoglobulin variable region heavy chain gene products in paraproteins from Iranian patients with multiple myeloma

The frequency of expression of immunoglobulin (Ig) variable region heavy (VH ) chain gene products was studied in 43 Iranian patients with mutiple myeloma (MM). The expressed VH gene families and associated cross-reactive idiotypes (CRI) were analysed by immunoblotting and ELISA, using peptide-induced polyclonal antibodies specific for VH 1-VH 6 gene families and monoclonal antibodies (MAb) recognising CRI linked to theVH 1, VH 3, VH 4 and VH 6 gene families. The results revealed that the VH 3 family (60. 5%) was the most predominant gene family. In contrast, no paraproteins were encoded by genes from the VH 2 gene family and only 2.3% were encoded by the VH 5 family. The panel of paraproteins tested rarely expressed the probed VH -associated CRI. Our results suggest that: 1-The Ig VH genes, may not be randomly expressed in the malignant plasma cells from Iranian patients with MM. 2- Some of the genes seem to be negatively selected or highly mutated, as evidenced by the lack of expression of the probed CRI.

Primary CNS lymphoma: clinical presentation, pathological classification, molecular pathogenesis and treatment

Primary CNS lymphomas (PCNSL) represent malignant non-Hodgkin's B cell lymphomas, which are confined to the central nervous system. They show a dramatic increase in frequency in the immunocompromised as well as in the immunocompetent population. Recent studies have identified germinal center B cells as the cellular origin of PCNSL; however, the details of their molecular pathogenesis still remain to be elucidated. Treatment recommendations are not clearly established. Radiotherapy (RT) is efficient in terms of tumor response, but not curative. Median survival after RT alone is about 1 year. According to the results of uncontrolled studies the combination of RT and chemotherapy based on high-dose methotrexate (HD-MTX) is most efficient in terms of survival rates. However, long-term neurotoxicity overshadows treatment efficacy, especially in patients over 60 years of age. The authors favor the systematic evaluation of chemotherapy alone with protocols including HD MTX, because unicenter results are promising in terms of both survival as well as quality of life in long term survivors.

Primary central nervous system lymphomas are derived from germinal-center B cells and show a preferential usage of the V4-34 gene segment

Primary central nervous system lymphomas (PCNSLs) have recently received considerable clinical attention due to their increasing incidence. To clarify the histogenetic origin of these intriguing neoplasms, PCNSLs from 10 HIV-negative patients were analyzed for immunoglobulin (Ig) gene rearrangements. All tumors exhibited clonal IgH gene rearrangements. Of the 10 cases, 5 used the V4-34 gene segment, and all of these lymphomas shared an amino acid exchange from glycine to aspartate due to a mutation in the first codon of the complementarity-determining region 1. No preferential usage of D(H), J(H), V(kappa), J(kappa), V(lambda), or J(lambda) gene segments was observed. All potentially functional rearrangements exhibited somatic mutations. The pattern of somatic mutations indicated selection of the tumor cells (or their precursors) for expression of a functional antibody. Mean mutation frequencies of 13. 2% and 8.3% were detected for the heavy and light chains, respectively, thereby exceeding other lymphoma entities. Cloning experiments of three tumors showed ongoing mutation in at least one case. These data suggest that PCNSLs are derived from highly mutated germinal-center B cells. The frequent usage of the V4-34 gene and the presence of a shared replacement mutation may indicate that the tumor precursors recognized a shared (super) antigen.

Non-antigen-specific B-cell activation following murine gammaherpesvirus infection is CD4 independent in vitro but CD4 dependent in vivo

The murine gammaherpesvirus MHV-68 multiplies in the respiratory epithelium after intranasal inoculation, then spreads to infect B cells in lymphoid germinal centers. Exposing B cells to MHV-68 in vitro caused an increase in cell size, up-regulation of the CD69 activation marker, and immunoglobulin M (IgM) production. The infectious process in vivo was also associated with increased CD69 expression on B cells in the draining lymph nodes and spleen, together with a rise in total serum Ig. However, whereas the in vitro effect on B cells was entirely T-cell independent, evidence of in vivo B-cell activation was minimal in CD4(+) T-cell-deficient (I-Ab-/-) or CD4(+) T-cell-depleted mice. Furthermore, the Ig present at high levels in serum was predominantly of the IgG class. Surprisingly, the titer of influenza virus-specific serum IgG in previously immunized mice fell following MHV-68 infection, suggesting that there was relatively little activation of memory B cells. Thus, CD4(+) T cells seemed both to amplify a direct viral activation of B cells in lymphoid tissue and to promote new Ig class switching despite a lack of obvious cognate antigen.

V(H) gene analysis of Burkitt's lymphoma in children from north-western Iran

Cases of Burkitt's lymphoma (BL) from north-western Iran were investigated for the usage and somatic mutational pattern of their immunoglobulin variable region genes. Potentially functional V(H) genes were amplified from 6/12 of the tumour masses and all of these were derived from the V(H)3 family, with 4/6 being derived from the most commonly used V(H)3 family member, V3-23. All of the tumour sequences were mutated from their germline counterparts, to varying degrees, with a mean level of 5.8%, indicating that the cell of origin had encountered the germinal centre. Intraclonal sequence heterogeneity was also evident in 4/6 of the lymphomas, showing that the tumour cells had undergone further somatic mutation following neoplastic transformation. Analysis of the five potentially functional mutated V(H) sequences showed a significant clustering of replacement mutations in the complementarity-determining region 2, consistent with a role for antigen in selection of tumour cell sequences. The pattern of extensive somatic mutation, and intraclonal variation, in these mainly EBV+ve tumours, was similar to that previously reported in V(H) sequences of EBV+ve endemic BL (eBL) and EBV-ve sporadic BL (sBL), with the mean level of somatic mutation lying between those reported for eBL (7.7%) and sBL (4.0%). However, VH gene bias and the distribution of mutations in the Iranian cases showed features which differed from those reported for endemic or sporadic BL.

Chronic lymphocytic leukemia B cells express restricted sets of mutated and unmutated antigen receptors

To better understand the stage(s) of differentiation reached by B-type chronic lymphocytic leukemia (B-CLL) cells and to gain insight into the potential role of antigenic stimulation in the development and diversification of these cells, we analyzed the rearranged VH genes expressed by 83 B-CLL cells (64 IgM+ and 19 non-IgM+). Our results confirm and extend the observations of a bias in the use of certain VH, D, and JH genes among B-CLL cells. In addition, they indicate that the VH genes of approximately 50% of the IgM+ B-CLL cells and approximately 75% of the non-IgM+ B-CLL cells can exhibit somatic mutations. The presence of mutation varies according to the VH family expressed by the B-CLL cell (VH3 expressers displaying more mutation than VH1 and VH4 expressers). In addition, the extent of mutation can be sizeable with approximately 32% of the IgM+ cases and approximately 68% of the non-IgM+ cases differing by > 5% from the most similar germline gene. Approximately 20% of the mutated VH genes display replacement mutations in a pattern consistent with antigen selection. However, CDR3 characteristics (D and JH gene use and association and HCDR3 length, composition, and charge) suggest that selection for distinct B cell receptors (BCR) occurs in many more B-CLL cells. Based on these data, we suggest three prototypic BCR, representing the VH genes most frequently encountered in our study. These data suggest that many B-CLL cells have been previously stimulated, placing them in the "experienced" or "memory" CD5(+) B cell subset.

Insight into Burkitt's lymphoma from immunoglobulin variable region gene analysis

Analysis of usage of V(H) and V(L) genes, and the degree and pattern of somatic mutation, has been used to investigate the cell of origin and clonal history in cases of Burkitt's lymphoma (BL). Tumor cell lines and biopsy material from patients with endemic, sporadic and AIDS-associated BL have been compared. V(H) genes were most commonly derived from the V(H)3 (52%) and V(H)4 (39%) families. This shows a similar gene usage of the V(H)3 family to that seen in the normal peripheral blood repertoire (55%), but a biased usage of the V(H)4 family (22% in normal). There was no restriction in V(L) gene usage. This overall distribution was similar in all subsets of BL. In all categories, there was significant somatic mutation in both V(H) and V(L) sequences. There was no evidence for accumulation of mutations in cell lines cultured in vitro indicating that all mutations in BL-derived cell lines have accumulated in vivo. The mean percentage level of mutation +/- standard deviation was greater in endemic BL (V(H) = 7.7 +/- 4.0, V(L) = 5.3 +/- 2.2) and AIDS-associated BL (V(H) = 7.5 +/- 3.6, V(L) = 3.9 +/- 1.9) than in sporadic BL (V(H) = 4.0 +/- 2.5, V(L) = 2.2 +/- 1.2). The pattern of somatic hypermutation was similar in V(H) and V(L) sequences of the different types of BL although the light chain genes were less mutated. Mutational patterns in the V(H) genes did not reveal a conventional role for antigen in selection of tumor cell sequences in 23/25 V(H) genes analysed. In contrast, patterns in V(L) sequences were consistent with a role for antigen in 8/13 sBL +/- eBL cases and 8/17 cases overall. The presence of EBV did not seem to influence the quantity or pattern of somatic mutations. Evidence for intraclonal variation was seen in uncloned cell lines from cases of eBL and AIDS-associated BL and confirmed in biopsy material in some, but not all cases of eBL, sBL and AIDS-associated BL examined. These common features indicate that the B-cells involved in all types of BL are derived from cells that have traversed the germinal centre, and that the somatic mutation mechanism may still be operative following neoplastic transformation. Overall, in 10/30 cases, there was evidence of significant clustering of replacement amino acids, in CDRs, particularly in V(L), indicating that the B-cell of origin is likely to have been selected by antigen.

De Novo CD5+ Diffuse Large B-Cell Lymphomas Express VH Genes With Somatic Mutation

To clarify the cellular origin of de novo CD5+ diffuse large B-cell lymphoma (CD5+ DLBL), particularly in comparison with other CD5+ B-cell neoplasms such as chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL), we analyzed the nucleotide sequence of the Ig heavy chain variable region (IgVH) genes of de novo CD5+ DLBL cases. All 4 cases examined had extensive somatic mutations in contrast with CLL or MCL. The VH gene sequences of de novo CD5+ DLBL displayed 86.9% to 95.2% homology with the corresponding germlines, whereas those of simultaneously analyzed CLL and MCL displayed 97.6% to 100% homology. The VH family used was VH3 in 1 case, VH4 in 2 cases, and VH5 in 1 case. In 2 of 4 examined cases, the distribution of replacement and silent mutations over the complementarity determining region and framework region in the VH genes was compatible with the pattern resulting from the antigen selection. Clinically, CD5+DLBL frequently involved a variety of extranodal sites (12/13) and lymph node (11/13). Immunophenotypically, CD5+ DLBL scarcely expressed CD21 and CD23 (3/13 and 2/13, respectively). These findings indicate that de novo CD5+ DLBL cells are derived from a B-1 subset distinct from those of CLL or MCL.

Differential Rates of Somatic Hypermutation in VH Genes Among Subsets of Chronic Lymphocytic Leukemia Defined by Chromosomal Abnormalities

Chronic lymphocytic leukemia (CLL) is a B-cell tumor involving small lymphocytes that generally express the CD5 antigen and low levels of surface Ig. Within this definition, there is heterogeneity among cases in cell morphology, karyotypic abnormalities, and clinical course. Trisomy 12, the most frequent karyotypic abnormality, is commonly found in a subset of CLL with atypical morphology. It has also been associated with advanced disease, and possibly with a less favorable prognosis. A further subset of cases with abnormalities involving chromosome 13q14 have typical lymphocyte morphology. Occasionally, the two abnormalities are found together. To assess the clonal history of the cell of origin in disease subsets defined by these two chromosomal abnormalities, we investigated the usage of VH genes and the pattern of somatic mutation in 10 cases of trisomy 12 with atypical morphology and eight cases of 13q14 abnormality with typical morphology. In addition, four cases with both chromosomal abnormalities were analyzed. Results confirm a common usage of the VH1 family in all subsets. However, the patterns of somatic mutation were distinct, with cases of trisomy 12 showing a minimal level of mutation (mean ± SD, 0.34% ± 0.86%) and cases of 13q14 abnormality showing significant levels (6.5% ± 1.67%). The four cases with both abnormalities showed a mixed pattern. All mutated cases had intraclonal homogeneity, and three of 10 had a pattern indicative of antigen selection. These results suggest that the clonal history of the two subsets of CLL may differ.