Utility of an immunoglobulin gene rearrangement assay based on multiplex PCR in detecting bone marrow involvement in B-cell non-Hodgkin lymphoma

No abstract available.

Presence of B-cell clones in angioimmunoblastic T cell lymphoma / 中华病理学杂志

<p><b>OBJECTIVE</b>To study the significance of B-cell clones in angioimmunoblastic T cell lymphoma (AITL) and the correlation with Epstein-Barr virus (EBV) and prognosis.</p><p><b>METHOD</b>The histopathologic features, T cell clonality and EBV positivity in 33 cases of AITL and 10 cases of peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) collected from May 2010 to February 2014 were analyzed by immunohistochemistry, PCR gene rearrangement and in situ hybridization. Follow-up data were also collected.</p><p><b>RESULTS</b>Of the 33 cases with AITL, seven cases (21.2%) exhibited clonal rearrangement of Ig genes; 21 cases (63.6%) were EBV positive. Seven cases had B-cell clones and all (7/7) were EBV positive; 14 of the 26 (53.8%) cases without B-cell clones were EBV positive. The difference between the two groups was statistically significant (P = 0.032). Four levels were made according to the number of EBV-labeled cells, Ig gene rearrangements, but there was no significant difference among levels 1, 2 and 3. There was no correlation between B-cell clones and prognosis (P = 0.263).</p><p><b>CONCLUSION</b>Clonal rearrangement of Ig genes is a common finding in AITL, and it is highly associated with EBV positivity, but not with the number of EBV-labeled cells. The clinical significance remains unclear; further study with more samples is warranted.</p>

Clinical Significance of Clonal Rearrangement of the Immunoglobulin Gene in the Bone Marrow of Patients with B-cell Non-Hodgkin Lymphoma

BACKGROUND: In the early stages of non-Hodgkin lymphoma (NHL), it can be difficult to recognize minimal morphological changes in the bone marrow (BM). In particular, when the quality of the BM biopsy is poor, determining BM involvement is limited to microscopic findings on BM aspiration. In this study, we compared the results of clonal immunoglobulin (IG) gene rearrangements with BM morphology results in B-cell NHL patients who underwent BM analysis as a staging workup and evaluated the usefulness of the clonal IG gene rearrangements for staging. METHODS: Forty two B-cell NHL patients were analyzed. Clonal rearrangements of the IG heavy chain (IGH), kappa light chain (IGK) and lambda light chain (IGL) genes were detected using the IdentiClone(TM) Clonality assay (InVivoScribe Technologies, USA). Clinical characteristics and outcomes were evaluated based on the detection of monoclonal IG gene rearrangements. RESULTS: Monoclonal IG gene rearrangements were found in 9 of 42 patients (21.4%). Microscopic BM involvement was found in only 2 of 42 patients (4.8%). The monoclonality rate of IG genes in BM was correlated with clinical stage and the international prognostic index (P<0.01). Patients with monoclonal IG gene rearrangements in BM had a significantly higher relapse rate (P=0.014) and poorer overall survival at 2 yr (P<0.01). CONCLUSIONS: Clonality analysis of BM in B-cell NHL can contribute to identification of patients with occult BM involvement with a significantly poorer overall survival despite normal BM histology.

Analysis of Immunoglobulin Gene Rearrangement: Comparison between BIOMED-2 Multiplex PCR and Conventional Nested PCR

BACKGROUND: Immunoglobulin (Ig) gene rearrangement analysis is a useful additional tool to detect clonality of B-lymphoproliferative disease and the method to detect immunoglobulin gene rearrangement is required the high sensitivity and specificity. BIOMED-2 multiplex PCR was designed for the evaluation of molecular clonality of lymphoid lesions. We evaluated the usefulness of the BIOMED-2 multiplex PCR by comparing it with conventional nested PCR. METHODS: Sixteen patients with malignant lymphoma and 5 with reactive lymph nodes were examined to assess the sensitivity, specificity, and accuracy between conventional nested PCR and BIOMED-2. All 3 tests performed using the BIOMED-2 kit for immunoglobulin (Ig) heavy chain (IGH) gene, Igkappa light chain (IGK) gene, and Iglambda light chain (IGL) gene, were used to analyze clonality. RESULTS: Both the methods showed 100% specificity (95% confidence interval, 56.6-100.0). The combination of IGH and IGK BIOMED-2 tests with or without IGL revealed the highest sensitivity (87.5%; range, 64.0-96.5%) and accuracy (90%; range, 0.70-0.97). Compared to the conventional method, the BIOMED-2 test for IGH showed a higher sensitivity (62.5%; range, 38.6-81.5%) and accuracy (71%, 0.50-0.86). CONCLUSIONS: These results suggest that, compared to the conventional method, BIOMED-2 has higher sensitivity and allows for easier interpretation while evaluating the clonality of B-lymphoproliferative disease.

Overrepresentation of specific gene segments of expressed immunoglobulin heavy chain variable region among unmutated and mutated patients with chronic lymphocytic leukemia / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the overrepresentation of specific gene segments of immunoglobulin heavy chain variable region (IgVH) among unmutated and mutated chronic lymphocytic leukemia (CLL) patients and its prognostic implication.</p><p><b>METHODS</b>Multiplex PCR was used to identify the expression of IgVH segment and its mutation status in CLL.</p><p><b>RESULTS</b>Analyses were successfully performed in 80 of 85 samples. Marked skewed IgVH families were disclosed. The most commonly used VH was VH3 (40.0%), followed by VH4 (30.0%), VHI (13.8%), VH2 (10.0%) and VH5, VH7 (2.5%). Fifty-six patients (70.0%) had mutated VH, 24 (30.0%) unmutated VH. Nine cases (11.3%) were with 100% germline sequence. Fifteen cases (15/24, 62.5%) in VH4, 29 (29/32, 90.7%) in VH3, and 4 (4/11, 36.3%) in VH1 had mutated VH. The most frequently used IgVH gene was VH4-39 (13.8%), and VH4-34 (8.8%). J4 (36/66, 54.5%) and D3 (25/66, 37.8%) were the most frequently used in J and D genes. The progression-free survival (PFS) was 82 and 17 months (P = 0.000), and the overall survival (OS) was 90 and 41 months (P = 0.009), respectively, for mutated and unmutated cases. Recurrent CDR3 sequences were found in our patients and 2 patients with VH1-69 had CDR3 sequences highly similar to those reported in literature.</p><p><b>CONCLUSION</b>There is difference in IgVH gene segment usage and mutational status in different area CLL patients. Recurrent CDR3 sequences were found in specific IgVH gene segments, which highlights the importance of immunoglobulin mediated stimulation in the development of CLL.</p>

Diffuse Large B-Cell Lymphoma Associated with Chronic Inflammation Manifested as a Soft Tissue Mass: Incidental Discovery on Histological Examination

We report an extraordinary case of diffuse large B-cell lymphoma arising in a cystic necrotic mass in a 35-year-old man who presented with a soft tissue mass at the site of previous surgery. A benign mass was surgically removed 17 years ago, after which a cystic lesion gradually developed at the same site. The resected mass appeared as a thick-walled cyst filled with brown necrotic and hemorrhagic material. On microscopic examination, the cyst wall was primarily necrotic tissue with some aggregates of large atypical lymphoid cells. These atypical cells were diffusely positive for CD20 and showed a high proliferation index, Epstein-Barr virus positivity, and clonal rearrangement of the immunoglobulin gene. His present condition was diagnosed as Epstein-Barr virus-associated diffuse large B-cell lymphoma arising from chronic inflammation. It is important to be aware of the clinical manifestations and histological features of this rare disease in light of diagnosis and treatment.

Assessment of BIOMED-2 assays for detection of clonal Ig gene rearrangements in mature B-cell lymphomas / 中华病理学杂志

<p><b>OBJECTIVE</b>To evaluate the efficiency of the BIOMED-2 PCR assay and its implication in the diagnosis of mature B-cell non-Hodgkin's lymphomas.</p><p><b>METHODS</b>Clinical, morphological and immunohistochemical features of 72 cases of non-Hodgkin's lymphomas were studied, including 25 reactive lymphoid hyperplasia, 37 diffuse large B cell lymphomas (DLBCL) and 35 extranodal marginal zone lymphomas of mucosa associated lymphoid tissues (MALT lymphoma and in addition, 25 cases of reactive lymphoid hyperplasia were used as the controls). DNA was exacted from the paraffin embedded formalin fixed tissue blocks and the quality of DNA was assessed using the BIOMED-2 specimen control reaction. Adequate samples were then analyzed by BIOMED-2 for immunoglobulin heavy and kappa light chain rearrangements.</p><p><b>RESULTS</b>Adequate DNA was obtained in 83 of 97 samples, including 60 mature B cell lymphomas and 23 reactive lymphoid hyperplasia. Clonal B-cell gene rearrangements were detected in 57 of 60 (95%) lymphomas. In contrast, clonal Ig gene rearrangements were not detected in any of the 23 cases of reactive lymphoid hyperplasia.</p><p><b>CONCLUSION</b>BIOMED-2 assay is highly sensitive and specific for the detection of clonal B cell gene rearrangement using routine paraffin embedded formalin fixed specimens.</p>

Construction of fusion gene between IgGHV and IL-2 as IgHV nucleic acid vaccine against lymphoma / 中国实验血液学杂志

The purpose of this study was to construct the IgHV and IL-2 coexpressed vector. The IgHV gene fragments were obtained from the peripheral blood of patients with lymphoma, and were cloned into eukaryotic expression vector. Meanwhile, the gene fragments of IgHV linked with gene of IL-2 were inserted into pcDNA3.0 to form a fusion gene of IgHV-IL-2. Then fusion genes were transfected into COS cells by Lipofectin and the expression of IL-2 was detected by ELISA. The results showed that the IgHV/pcDNA3.0 expression vector was successfully constructed. The 3' end of IgHV was linked to IL-2 gene, and IL-2 could be correctly expressed. In conclusion, the expression vector of IgHV-IL-2 can express IL-2 correctly in COS cells.

Patogênese da leucemia linfóide crônica / Pathogenesis of chronic lymphocytic leukemia

A leucemia linfóide crônica foi durante muito tempo entendida como uma doença relativamente homogênea causada pela acumulação de linfócitos B monoclonais, imuno-incompetentes e com graves distúrbios nos mecanismos normais de apoptose. Evidências recentes demonstram que as células leucêmicas LLC constituem-se em linfócitos B previamente expostos a antígenos, ou seja, provavelmente imunoðcompetentes. Além disso, ao contrário do que se acreditava, o aparato de apoptose destas células parece estar intacto. Pelo menos dois subgrupos distintos de LLC podem ser caracterizados por particularidades imunobiológicas, cursos clínicos e prognósticos distintos. A presença de mutações somáticas em genes da região variável de imunoglobulina define estes dois subtipos, onde o grupo não mutado apresenta melhor prognóstico, ao passo que o grupo com mutações indica cursa com pior prognóstico. A célula de origem da LLC, ou seja, a célula em que o evento leuceðmogênico inicial ocorre provavelmente é um progenitor linfóide, com boa parte da sua maquinaria transcipcinal comprometida com a linhagem B, mas com algumas características de linfócitos T anormalmente expressas. A progressão destas células para os linfócitos tipicamente LLC depende de estimulação antigênica. Tanto as formas não mutada como mutada expressam BCR, mas, aparentemente, as células com mutação são anérgicas. Células de LLC não mutada apresentam telômeros mais curtos que nos casos com mutação, indicando que os primeiros devem sofrer um número maior de divisões celulares e, portanto, uma maior probabilidade de adquirirem mutações. A expressão anômala de ZAP70, uma tirosina-quinase importante no processo de fosforilação de CD3 em linfócitos T, associa-se fortemente com o status não mutado e pode ser utilizado como um possível "surrogate" para a avaliação prognóstica. Alterações citogenéticas são freqüentes em LLC, mas provavelmente são fenômenos tardios da doença e a sua aquisição apresenta...

For decades, chronic lymphocytic leukemia (CLL) has been regarded as homogeneous entity caused by the accumulation of monoclonal and immunoincompetent B cells with dysfunctional apoptotic pathways. Recently, many of these certainties have been questioned by evidence that demonstrate that CLL cells have been previously challenged by antigens, and therefore are immunoðcompetent cells. Moreover, in proliferative compartments, like the mantle zone of lymphoid organs or pseudo-follicles in the bone marrow, defects in proliferation seems to be as important as apoptosis impairment in the pathogenesis of the disorder. Two distinct subgroups of CLL can be segregated based on immunoðbiologic characteristics, clinical course and outcomes. The two subgroups can be identified by the presence of somatic mutations in the variable region of the heavy chain gene. The unmutated group presents a better outcome and is probably composed of anergized B cells previously exposed to an antigen which frequently affects a common segment of the variable region. The mutated group courses with a poorer prognosis and commonly presents an abnormal expression of ZAP70, a typical T-cell tyrosine kinase. The cell which originates CLL is a very early lymphocyte that still bears some T-cell characteristics, such as CD5 and ZAP70 expressions, but with the transcriptional machinery committed to the B-lineage. The original genetic lesion in this CLL primary cell is unknown. Cytogenetic abnormalities are frequently seen in the circulating lymphocytes and are probably late events in the pathogenesis of CLL.

Receptor selection and B cell immune tolerance / 生物医学工程学杂志

The immune system of mammalian has developed sophisticated mechanism to deal with diverse unknown antigens by random rearrangement of V, D and J antigen gene fragments. The immune self-tolerance is the mechanism to avoid self-destruction by the gene rearrangement generated autoreactive lymphocytes. Until recently it was believed that autoreactive lymphocytes are either deleted or rendered unable to respond by the supposed cell or clone selection mechanism. However, recent findings from a number of laboratories suggest instead of cell selection but receptor selection plays an essential role in immune self-tolerance. Receptor selection is carried out by secondary or nested rearrangement of antigen receptor gene fragments, and can occur at different stages of lymphocyte differentiation. Furthermore, secondary rearrangement of receptor gene also plays an important role in shaping immune response after the interaction of receptor with antigen by altering its specificity.

Progress in single-domain antibody derived from heavy-chain antibody / 生物工程学报

Functional heavy-chain antibodies (HCAbs) lacking light chains occur naturally in camels. The variable domain of heavy chain of heavy-chain antibody is referred to VHH. The VHH gene family is homologous to human VH subgroup III. The single-domain VHH antibodies are constructed by cloning the variable domains of HCAbs. Compared to human VHs, VHH germ-line sequences contain some hallmark substitutions in framework region 2, including V37F(Y), G44 E, L45 R, W47G. The substitutions at positions 44, 45, 47 are often used to camelise the human VHs. Being a small binders, VHH antibodies are well expressed, extremely stable and very soluble. Camelised human VHs are proved to exhibit the same qualities as those of VHH antibodies. The single-domain VHH antibodies will be useful in the drug development and basic research.

Characteristics of immunoglobulin heavy chain variable region genes in childhood B-cell acute lymphoblastic leukemia / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the origin of childhood B-cell acute lymphoblastic leukemia (B-ALL) and its epitopes recognized by cytotoxic T lymphocytes (CTL) in immunoglobulin heavy chain variable region (IgHV).</p><p><b>METHODS</b>Seven IgHV gene families were respectively amplified by PCR and directly sequenced in 108 childhood ALL. The amino acid sequences were deducted from sequenced nucleotides. Bioinformatics was applied to analyses of recombination patterns, somatic mutations and germline gene segments usage, and to prediction of epitopes recognized by CTL.</p><p><b>RESULTS</b>IgHV gene rearrangements were identified in 66% of the cases, including 37 (52.1%) monoallelic rearrangements, 26 (36.6%) biallelic rearrangements and 8 (11.3%) oligoclonal rearrangements. Among the obtained 40 B-ALL IgHV gene sequences, 8 (20.0%) were in frame rearrangements without stop codons. V(H3) (11/40), V(H4) (11/40) and V(H1) (8/40) amounted to 75% rearranged V(H) families. V(H)(4-59) and V(H)(4-34) were the most frequently rearranged V(H)(4) family gene segments. Usage of D2 and D3 families was most prominent (35.9% and 28.2%, respectively). Increased frequency of D7-27 (15.4%) was found as compared to that of normal peripheral B lymphocytes (P = 0.02). J(H)(6) was found in 47.5% rearrangements followed by J(H)(4) (27.5%). 8/40 (20.0%) DJ(H) junctions lacked N nucleotides, which was higher than that reported for normal peripheral B lymphocytes (P = 0.02). 17.5% B-ALL IgHV contained scattered replacement mutations with replacement (R) to silent (S) substitution ratio (R/S ratio) <or= 1 in complementarity determining region (CDR). Above 80% potential HLA class I molecule-binding peptides were derived from framework regions of immunoglobulin heavy chains in 26 B-ALL cases and 1 - 2 peptides of the same IgHV family were shared by B-ALL.</p><p><b>CONCLUSION</b>B-ALL originated from progenitor or precursor B lymphocytes. B-ALL IgHV genes are of germline characteristics. Potential T cell epitopes were derived from framework regions 1 and 3 of immunoglobulin heavy chain in B-ALL.</p>

Detection of IgH gene rearrangement in B-cell non-Hodgkin's lymphoma and application of gel-scan method / 中华病理学杂志

<p><b>OBJECTIVE</b>To develop a protocol for gene rearrangement study in non-Hodgkin's lymphoma (NHL) by PCR-directed gel-scan method and to set up quantitative criteria for IgH gene rearrangement which can be applied in the follow up of lymphoma patients.</p><p><b>METHODS</b>IgH gene rearrangement studies were carried out in 96 cases of B-cell NHL. The detection rate of clonality was evaluated. Sixty-five cases of IgH gene rearranged cases proven by FR3A-directed PCR and PAGE and 8 cases of benign lymphoid tissues (5 cases of reactive lymphoid hyperplasia, 3 cases of chronic tonsillitis), 5 cases of normal peripheral blood mononuclear cells were analyzed by gel-scan method and the proportion of h1/h2 (heights of peak1 and peak2 of gel-scan) was calculated.</p><p><b>RESULTS</b>The detection rate of IgH gene clonality was up to 68% using primer FR3A in the 96 B-cell NHL cases. The detection rate was up to 61% using primer FR2A. With a combination of primers FR3A and FR2A, the detection rate increased to 83%. Gel-scan curve showed that the value of h1/h2 was greater than 3 in all the 65 cases with IgH gene rearranged. In the 8 benign lymphoid tissue cases showed h1/h2 < 1.5, 5 cases with normal peripheral blood mononuclear cells showed a bell-shaped curve.</p><p><b>CONCLUSIONS</b>In the gel-scan curve of gene rearrangement studies in non-Hodgkin's lymphoma samples, the value of h1/h2 greater than 3 represents a true clonal proliferation. The peaks with relative heights less than 1.5 may not be significant and likely represent polyclonal cell population. A value between 1.5 and 3 however requires clinical follow-up. The success rate of rearrangement studies in B-cell NHL can be increased by using a combination of primers FR3A and FR2A.</p>

A Case of Idiopathic Lymphocytoma Cutis

The pseudolymphoma of the skin has the architectural and cytological features of a neoplastic proliferation of lymphoid tissue but pursue a benign course. Cutaneous B cell pseudolymphoma (CBPL) shares many histopathologic and clinical features with cutaneous B cell lymphoma (CBCL). Therefore, the differentiation between CBPL and CBCL is often very difficult, but it is important because each of them has a different therapeutic consequence. Recently, immunoglobulin gene rearrangement is considered as a reliable technique for differentiation of CBPL with CBCL. We herein report a case of idiopathic lymphocytoma cuffs, showing a typical nodular infiltrate of lymphocytes that formed a follicular germinal center resembling reactive lymph nodes with numerous tingible bodies, and that revealed a polyclonality in the immunoglobulin gene rearrangement.

The role of complement in the modulation by fluid-phase IgG of the production of reactive oxygen species by polymorphonuclear leukocytes stimulated with IgG immune complexes

The production of reactive oxygen species (ROS) by polymorphonuclear leukocytes (PMN) can be induced by immune complexes and is an important component of phagocytosis in the killing of microorganisms, but can also be involved in inflammatory reactions when immune complexes are deposited in tissues. We have observed that fluid-phase IgG can inhibit the generation of ROS by rabbit PMN stimulated with precipitated immune complexes of IgG (ICIgG) in a dose-dependent manner, acting as a modulatory factor in the range of physiological IgG concentrations. This inhibitory effect is compatible with the known affinity (Kd) of monomeric IgG for the receptors involved (FcRII and FcRIII). The presence of complement components in the immune complexes results in a higher stimulation of ROS production. In this case, however, there is no inhibition by fluid-phase IgG. The effect of complement is strongly dependent on the presence of divalent cations (Ca2+ or Mg2+) in the medium, whereas the stimulation of ICIgG (without complement) does not depend on these cations. We have obtained some evidence indicating that iC3b should be the component involved in the effect of complement through interaction with the CR3 receptor. The absence of the inhibitory effect of fluid-phase IgG in ROS production when complement is present in the immune complex shows that complement may be important in vivo not only in the production of chemotactic factors for PMN, but also in the next phase of the process, i.e., the generation of ROS.

Cell biology, molecular embryology, Lamarckian and Darwinian selection as evolvability

The evolvability of vertebrate systems involves various mechanisms that eventually generate cooperative and nonlethal functional variation on which Darwinian selection can operate. It is a truism that to get vertebrate animals to develop a coherent machine they first had to inherit the right multicellular ontogeny. The ontogeny of a metazoan involves cell lineages that progressively deny their own capacity for increase and for totipotency in benefit of the collective interest of the individual. To achieve such cell altruism Darwinian dynamics rescinded its original unicellular mandate to reproduce. The distinction between heritability at the level of the cell lineage and at the level of the individual is crucial. However, its implications have seldom been explored in depth. While all out reproduction is the Darwinian measure of success among unicellular organisms, a high replication rate of cell lineages within the organism may be deleterious to the individual as a functional unit. If a harmoniously functioning unit is to evolve, mechanisms must have evolved whereby variants that increase their own replication rate by failing to accept their own somatic duties are controlled. For questions involving organelle origins, see Godelle and Reboud, 1995 and Hoekstra, 1990. In other words, modifiers of conflict that control cell lineages with conflicting genes and new mutant replication rates that deviate from their somatic duties had to evolve. Our thesis is that selection at the level of the (multicellular) individual must have opposed selection at the level of the cell lineage. The metazoan embryo is not immune to this conflict especially with the evolution of set-aside cells and other modes of self-policing modifiers (Blackstone and Ellison, 1998; Ransick et al., 1996. In fact, the conflict between the two selection processes permitted a Lamarckian soma-to-germline feedback loop. This new element in metazoan ontogeny became the evolvability of the vertebrate adaptive immune system and life as we know it now. We offer the hypothesis that metazoan evolution solved this ancient conflict by evolving an immunogenetic mechanism that responds with rapid Lamarckian efficiency by retaining the ancient reverse transcriptase enzyme (RNACopyright DNA copying discovered by Temin in 1959 (see Temin, 1989) and found in 1970 in RNA tumor viruses by Temin and Baltimore), which can produce cDNA from the genome of an RNA virus that infects the cells. It seems that molecular

Evidence for V(H) Gene Replacement in Human Fetal B Cells

BACKGROUND: In contrast to evidences of Ig H chain receptor editing in transformed cell lines and transgenic mouse models, there has been no direct evidence that this phenomenon occurs in human developing B cells. METHODS: V(H)DJ(H) rearrangements were obtained from genomic DNA of individual IgM- B cells from liver and IgM+B cells from bone marrow of 18 wk of gestation human fetus by PCR amplification and direct sequencing. RESULTS: We found three examples of H chain receptor editing from IgM+ and IgM+human fetal B cells. Two types of V(H) replacements were identified. The first involved V(H) hybrid formation, in which part of a V(H) gene from the initial VDJ rearrangement is replaced by part of an upstream V(H) gene at the site of cryptic RSS. The second involved a gene conversion like replacement of CDR2, in which another V(H) gene donated a portion of its CDR2 sequence to the initial VDJ rearrangement. CONCLUSION: These data provide evidence of receptor editing at the H chain loci in developing human B cells, and also the first evidence of a gene conversion event in human Ig genes.

Isolation of Human scFv Antibodies Specific for House Dust Mite Antigens from an Asthma Patient by Using a Phage Display Library

BACKGROUND: In order to characterize human antibodies with specificity for mite allergens at the molecular level, a scFv phage display library was constructed using peripheral blood mononuclear lymphocytes from an asthma patient allergic to mite as Ig gene sources. METHODS: Immunoglobulin VH and V gene fragments were obtained by polymerase chain reaction, and randomly combined in pCANTAB-5E vector. The resulting human scFv phage display library had 3 X 10(4) independent clones, and biopanning was performed with house dust mite extracts. RESULTS: Four scFv clones specific for house dust mite extract were isolated. Immunoblot assay showed that our clones reacted to 25 kDa and 50~60 kDa proteins with unknown identity in mite extracts. Sequence analysis indicated that two clones (b7 and c15) are identical, and all clones belong to human VH3 subgroup. On the other hand, light chain usage was different in that two clones (a2 and b7/c15) belonging to V kappa 4 subgroup, but a4 used V kappa 1 light chain gene. CONCLUSION: Our approach should facilitate provision of useful information on the antibody responses against allergens at the molecular level in humans.

Isolation of Mouse Ig Heavy and Light Chain Genomic DNA Clones, and Construction of Gene Knockout Vector for the Generation of Humanized Xenomouse

BACKGROUND: Monoclonal antibodies (mAb) of rodent origin are produced with ease by hybridoma fusion technique, and have been successfully used as therapeutic reagents for humans after humanization by genetic engineering. However, utilization of these antibodies for therapeutic purpose has been limited by the fact that they act as immunogens in human body causing undesired side effects. So far, there have been several attempts to produce human mAbs for effective in vivo diagnostic or therapeutic reagents including the use of humanized xenomouse that is generated by mating knockout mice which lost Ig heavy and light chain genes by homologous recombination and transgenic mice having both human Ig heavy and light gene loci in their genome. METHODS: Genomic DNA fragments of mouse Ig heavy and light chain were obtained from a mouse brain lamda genomic library by PCR screening and cloned into a targeting vector with ultimate goal of generating Ig knockout mouse. RESULTS: Through PCR screening of the genomic library, three heavy chain and three light chain Ig gene fragments were identified, and restriction map of one of the heavy chain gene fragments was determined. Then heavy chain Ig gene fragments were subcloned into a targeting vector. The resulting construct was introduced into embryonic stem cells. Antibiotic selection of transfected cells is under the progress. CONCLUSION: Generation of xenomouse is particularly important in medical biotechnology. However, this goal is not easily achieved due to the technical difficulties as well as huge financial expenses. Although we are in the early stage of a long-term project, our results, at least, partially contribute the successful generation of humanized xenomouse in Korea.