Chemical shift differences between free and Fab-bound peptide correlate with a two-stage selection of peptide sequences from a random phage display library to delineate critical and non-critical residues for antibody recognition

Epitope libraries provide a method to identify peptide ligands for antibodies, receptors or other binding proteins. As such, they provide a powerful tool to rapidly identify lead ligands in the drug discovery process. In an attempt to correlate structural information with the results from peptide screening, we have used NMR spectroscopy of peptide/antibody complexes to demonstrate that core residues identified through a two-stage selection process undergo a larger structural change upon binding antibody than do positions in the peptide amenable to a variety of side chains. The model system used was the M2 monoclonal antibody/Flag? octapeptide epitope system. We have analyzed two peptides: Ac-Asp-Tyr-Lys-Leu-Gly-Asp-Asp-Leu-NH₂ (peptide l), which contains several non-core positions randomized, and Ac-Asp-Tyr-Lys-Asp-Asp-Asp-Asp-Leu-NH₂ (peptide 2), which closely corresponds to the original Flag? sequence. Enrichment of the peptides with ¹⁵N facilitated the investigation by permitting spectral editing of the peptide resonances in the presence of antibody. For peptide 1 the absolute shifts for the free vs. Fab-bound peptide were found to be largest for the amide groups of Asp-1 and Asp-6, in agreement with classification of these residues as critical by the phage display library selection process. For peptide 2 the largest absolute shifts were observed for Asp-1 and Asp-4, with the other aspartic acid residues also showing significant but smaller changes. © Munksgaard 1995.     

Immunohistochemical differentiation of metastases of renal carcinomas versus other carcinomas with anti-γGT monoclonal antibody 138H11

Aims : Adenocarcinomas account for about 60% of metastatic cancers of unknown primary (CUP) site. In such a clinical CUP situation, histopathologists are challenged to differentiate renal cell carcinomas (RCC) from other adenocarcinomas with similar immunophenotypes, especially chemotherapeutically treatable mammary and ovarian carcinomas. Methods and results : Recently, we produced a monoclonal antibody (mAb), designated 138H11, against human gamma-glutamyltransferase (γGT), which stained over 98% primary clear cell and chromophilic RCC on frozen sections. The 138H11 epitope could not be stained using conventional techniques in most paraffin-embedded sections of the same origin, due to destruction by formalin fixation below the detection level. Here, we demonstrate that mAb 138H11 can specifically stain γGT in paraffin-embedded primary and metastatic RCC after enhancement with an ultrasensitive immunohistochemical method. We analysed a selected subgroup of adenocarcinomas with immunophenotypes which would not allow a differentiation from RCC in a CUP situation. We found a predominantly membranous expression of the 138H11 target antigen in 26/51 primary RCC and 15/34 metastatic RCC. In contrast, all 43/43 primary ovarian and bronchial carcinomas as well as 54/54 metastases of ovarian, mammary, bronchial and gastric carcinomas were negative for mAb 138H11. Conclusions : The data suggest that mAb 138H11 is useful for the immunohistochemical differentiation of RCC from other metastatic adenocarcinomas if the primary site of the tumour is not known.     

Characterization of Monoclonal Antihuman-B-Cell Antibody BL13 as an Anti-C3d-Receptor (CR2) Antibody

BL13, a mouse monoclonal IgG1 antibody raised against human B cells, blocked the function of the C3d receptor (CR2) and bound with high affinity (5 X 10(8) L M-1) to CR2 on B lymphoma cells. Following capping with the second antibody, BL13 inhibited C3d-dependent rosette formation of Daudi and Raji cells and C3b-dependent CR2-mediated rosette formation with B lymphoma cells, but did not inhibit CR1-mediated rosettes between C3b-bearing cells and peripheral blood lymphocytes. Competitive binding experiments between biotinylated BL13 or anti-CR2 antibody HB-5 and unlabelled antibodies demonstrated that BL13 bound to an epitope that is distinct from that recognized by HB-5, and closely associated with that recognized by monoclonal antibody anti-B2. BL13 only reacted with some B cells and follicular dendritic cells in germinal centres in human lymph nodes, whereas HB-5 strongly reacted with circulating B cells and bound to most cells in the follicles. These results demonstrate the heterogeneity of antigenically defined CR2.     

Phenotypical and Functional Differentiation of CD4+ CD45RA+ Human T Cells Following Polyclonal Activation

Human CD4+ T cells differ in their expression of the leucocyte common antigen. Antibodies detecting certain forms (CD45RA and CD45RO) of this antigen have been used to identify and isolate subpopulations of the CD4+ T cells. These isolated subsets have been shown to have different abilities concerning lymphokine production and provision of help to B cells for Ig production. When these T-cell subsets were activated in vitro with polyclonal activators, the production. When these T-cell subsets were activated in vitro with polyclonal activators, the CD45RA+ cells lost this marker and gained the expression of CD45RO. This was true for all mitogens used in this report, i.e. accessory cell-dependent stimulation with SEA and accessory cell-independent activation with PMA or PHA. A correlation between proliferation and differentiation was observed, but this was probably not causative as stimulation with PMA in the absence of DNA synthesis resulted in the acquisition of CD45RO and loss of the CD45RA antigen. Moreover, cells proliferating vigorously for long periods of time expressed both markers at significant levels, which suggests that proliferation did not automatically result in complete loss of the CD45RA marker. The phenotypical differentiation was associated with a functional differentiation which induced the stimulated cells' ability to act as helper cells for Ig production and to produce gamma interferon (IFN-gamma). The results obtained in this study support the contention that the CD45RA+ cells are precursors of the CD45RO+ cells and that the two subsets represent different maturational stages of the same lineage.     

The LFA-3 Adhesion Pathway is Differently Utilized by Superantigen-Activated Human CD4+ T-Cell Subsets

The superantigen SEA binds to MHC class II molecules and activates a large fraction of T cells as a result of interaction with particular TCR-V beta sequences. MHC class II transfected CHO cells induce a marginal CD4+ T-cell proliferation in the presence of SEA. CHO cells transfected with both MHC class II and LFA-3 (HLA-DR4/LFA-3 double transfectants) supported a vigorous T-cell proliferation and required 1000-fold lower SEA concentration than DR4-transfected cells. DR4/LFA-3 double transfectants presenting SEA to CD4+ T cells induced large amounts of IFN-gamma, while single DR4 transfectants failed to elicit IFN-gamma production. CD4+45RA+ naive T cells proliferated much more strongly compared with CD4+45R0+ memory T cells when SEA was presented by the DR4/LFA-3-transfected cells. In contrast, IFN-gamma production was only detected in CD4+45R0+ memory cells. The enhanced proliferation by the CD4+45RA+ naive T cells was not due to a stronger binding to the accessory DR4/LFA-3 cells. Human CD4+ T-cell lines mediated a low level of SEA-dependent cell-mediated cytotoxicity (SDCC) against DR4 target cells, whereas a strong SDCC was mediated against DR4/LFA-3-expressing target cells. These results demonstrate that superantigen-activated human CD4+ T cells require the adhesion molecule LFA-3 for optimal stimulation and that the CD4+ naive and memory T-helper cells are different in their response to LFA-3 as an accessory molecule.     

Comparative anticoagulant activity and influence on thrombin generation of dextran derivatives and of a fucoidan fraction

CMDBS compounds are synthetic dextran derivatives with a random distribution of glucosyl units substituted with carboxymethyl, benzylamide, sulfonate, and sulfate groups. Fucoidans are sulfated polysaccharides extracted from brown seaweeds. CMDBS and fucoidans exhibit anticoagulant activity which depends on their chemical composition and molecular weight. Tested with purified proteins, these compounds catalyse thrombin (EC 3.4.21.5) inhibition mainly via heparin cofactor II (HCII). We investigated the mechanism involved in the anticoagulant activity of these polysaccharides relative to that of heparin. Three CMDBS with different chemical compositions were studied to evaluate the effect of sulfate and sulfonate groups on the anticoagulant activity. The fucoidan fraction was extracted from the brown seaweed Ascophylum nodosum. The clotting assays (activated partial thromboplastin time, thrombin time, prothrombin time) were significantly prolonged in the presence of CMDBS and fucoidan, which were less active than heparin. To investigate the action mechanism of these polysaccharides, thrombin generation tests (TGT) were performed on human plasma in the presence of several CMDBS and a fucoidan fraction. The results showed an inhibition of thrombin generation in contact-activated plasma in the presence of both polysaccharides, with a prolonged lag phase preceding the burst of thrombin generation. In thromboplastin-activated plasma, thrombin generation was inhibited by CMDBS and fucoidan, with a prolonged lag phase only in the presence of CMDBS. The data obtained with each polysaccharide, compared to those obtained with heparin (our study) and hirudin (published data), led to hypothesize that fucoidan could act, like heparin, by forming complexes with the inhibitor (although antithrombin (AT) in the case of heparin, and HCII for fucoidan), while CMDBS could act, like hirudin, by forming complexes with thrombin.     

Joint health and functional ability in children with haemophilia who receive intensive replacement therapy

Summary. Joint physical examination is an important outcome in haemophilia; however its relationship with functional ability is not well established in children with intensive replacement therapy. Boys aged 4–16 years were recruited from two European and three North American treatment centres. Joint physical structure and function was measured with the Haemophilia Joint Health Score (HJHS) while functional ability was measured with the revised Childhood Health Assessment Questionnaire (CHAQ₃₈). Two haemophilia‐specific domains were created by selecting items of the CHAQ₃₈ that cover haemophilia‐specific problems. Associations between CHAQ, HJHS, cumulative number of haemarthroses and age were assessed. A total of 226 subjects – mean 10.8 years old (SD 3.8) – participated; the majority (68%) had severe haemophilia. Most severe patients (91%) were on prophylactic treatment. Lifetime number of haemarthroses [median = 5; interquartile range (IQR) = 1–12] and total HJHS (median = 5; IQR = 1–12) correlated strongly (ρ = 0.51). Total HJHS did not correlate with age and only weakly (ρ = ?0.19) with functional ability scores (median = 0; IQR = ?0.06–0). Overall, haemarthroses were reported most frequently in the ankles. Detailed analysis of ankle joint health scores revealed moderate associations (ρ = 0.3–0.5) of strength, gait and atrophy with lower extremity tasks (e.g. stair climbing). In this population, HJHS summating six joints did not perform as well as individual joint scores, however, certain elements of ankle impairment, specifically muscle strength, atrophy and gait associated significantly with functional loss in lower extremity activities. Mild abnormalities in ankle assessment by HJHS may lead to functional loss. Therefore, ankle joints may warrant special attention in the follow up of these children.     

The burden of HCV treatment in patients with inherited bleeding disorders

Summary. Many patients with inherited bleeding disorders are infected with hepatitis C virus (HCV). Antiviral treatment, consisting of pegylated interferon and ribavirin, has many side‐effects. The aim of the study was to prospectively assess the occurrence and course of side‐effects and changes in health‐related quality of life (HRQoL) during antiviral treatment in patients with inherited bleeding disorders and chronic HCV. Forty‐seven patients were followed during antiviral treatment. Side‐effects of treatment were recorded, and the Beck Depression Inventory and the RAND‐36 HRQoL questionnaire were administered at regular intervals. Frequently reported side‐effects were fatigue (100%), headache (94%), pruritus and skin rash (94%), concentration problems (89%), decreased appetite (89%), fever, irritability and hair loss (all 85%). Many side‐effects disappeared soon after end of treatment, but 4 weeks after cessation fatigue, concentration problems and sleeping problems were still present in more than 30% of patients. Dose reduction was necessary in 21 patients (45%), mostly because of decreasing weight or haemoglobin levels. Two patients stopped treatment prematurely because of side‐effects. Depression was present in 28 patients (60%). HRQoL decreased significantly during treatment in all RAND‐36 domains, and increased again within 4 weeks after treatment. Major side‐effects were similar in patients with successful (n = 31, 66%) and unsuccessful antiviral treatment. In patients with inherited bleeding disorders and chronic HCV, antiviral treatment has many, but mostly transient side‐effects and a significant impact on quality of life. Careful follow‐up and management of side‐effects will ensure optimal compliance and treatment results.     

bcl-1 REARRANGEMENT AND CYCLIN D1 PROTEIN EXPRESSION IN MANTLE CELL LYMPHOMA

Centrocytic lymphoma, or mantle cell lymphoma (MCL), is characterized by a chromosomal translocation t(11;14) (q13;q32) involving the bcl-1 locus on chromosome 11. Cyclin D1 is a cell-cycle regulatory protein essential for G1–S transition and has been identified as a potential transforming gene affected by the translocation. In this study, 32 cases of MCL were analysed for the bcl-1 rearrangement and cyclin D1 protein expression. In 17 cases, a rearrangement at the major translocation cluster of bcl-1 could be detected. Twenty-four cases exhibited nuclear cyclin D1 expression that was not detectable in other B-cell lymphomas ( n =40) or in normal B-cells. In nine MCL samples, cyclin D1 was expressed without a detectable bcl-1 rearrangement. The detection of a t(11;14) by means of classical cytogenetics in one of these cases, however, may suggest that this discrepancy could be due to chromosomal breakages outside the typical translocation cluster region. In two cases, a bcl-1 rearrangement was not accompanied by cyclin D1 expression. This study provides further evidence that cyclin D1 is involved in the pathogenesis of MCL and can be exploited as a diagnostic marker in the differential diagnosis of B-cell lymphomas and in the identification of MCL.