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At least 19 recordsLinked to original sources
PubMed1977

Novel idiotypic and antigen-binding characteristics in two anti-dinitrophenyl monoclonal antibodies.

Monoclonal anti-dinitrophenyl antibodies generated in the splenic focus system from B cells of adult BALB/c mice were studied for the presence or absence of murine anti-T15 (M anti-T15) reactivity and for their ability to bind phosphorylcholine (PC). Two foci of the 680 clones analyzed bound PC, and one of these antibodies reacted with M anti-T15 and anti-Fab on a 1:1 weight basis. The discovery of a clonotype reactive with M anti-15 but not with rabbit anti-T15 (R anti-T15) serum, the converse of the R anti-T15+, M anti-T15- clonotype identified in the PC-specific repertoire, points to the novel idiotypic relationships which may be found among homogeneous antibodies binding diverse antigens. The R anti-T15-, M anti-T15+ clonotype may represent a distinct set of hypervariable region sequences inserted into the T15 framework or may be a somatic variant of the T15 germ-line sequence. In addition, the maximum frequency with which this clonotype occurs within the B-cell pool is estimated.

Animals↗
PubMed1979

Separation of functional subsets of human T cells by a monoclonal antibody.

A monoclonal antibody was produced to human peripheral blood T cells. This hybridoma antibody, termed OKT4, was reactive by indirect immunofluorescence with only 55-60% of the peripheral blood T cell population (OKT4+) and unreactive with normal B cells, null cells, and macrophages. The OKT4- T cell population contained the previously described TH2+ subset that has been shown to contain cytotoxic/suppressor cells. With cell-sorter separation of OKT4+ and OKT4- cells, it was shown that these T cell subsets were functionally discrete. Both gave proliferative responses with concanavalin A, alloantigens, and phytohemagglutinin although OKT4+ cells were much more responsive to the latter. OKT4+ cells alone responded to soluble antigens whereas OKT4- cells alone were cytotoxic after alloantigenic sensitization of unfractionated T cells. However, both OKT4+ and OKT4- cells were required during sensitization for optimal development of cytotoxicity. These data suggest that the OKT4+ subset represents a helper population and that the OKT4- subset contains the cytotoxic effector population. OKT4 could be a valuable reagent for determining alterations of these functional subsets in human diseases.

Antibody Specificity↗
PubMed2026

Systematic review of the mutations in the active antigenic site Ø of the prefusion F protein of the Respiratory Syncytial Virus (RSV) following the implementation of monoclonal antibody prophylaxis.

BACKGROUND: Monoclonal antibody (mAb) nirsevimab, which targets the antigenic site &#xd8; of the prefusion F protein (pre-F) of RSV, was introduced for RSV prophylaxis in several countries. METHODS: A systematic search was conducted between January 1, 2022, and July 31, 2026 for studies analyzing substitutions within the epitope of pre-F RSV protein, which is the target of nirsevimab, after the implementation of the mAb. We searched across PubMed, Scopus, Web of Science and ClinicalTrial.gov for studies involving children with confirmed RSV infection, that conducted genomic analysis. RESULTS: Seven studies (five observational and two randomized controlled trials) including 2156 RSV-positive samples (RSV-A: 1347, RSV-B: 809) were analyzed. RSV-A strains showed limited variability within antigenic site &#xd8;, with K65R being the most common substitution and K209E being the only intermediate-resistance RSV-A substitution. RSV-B strains demonstrated substantially higher substitution frequencies, particularly involving I206M, Q209R, and S211N. Most identified substitutions appeared to represent naturally occurring polymorphisms and retained susceptibility to nirsevimab, while multiple RSV-B substitutions and combinations involving residues 64-68 and 204-208 demonstrated reduced susceptibility or high-level resistance. Resistance-associated variants were detected in 28 of 2156 (1.3%) RSV-positive samples and exclusively among nirsevimab breakthrough infections. In a sub-analysis restricted to nirsevimab-treated individuals, resistance-associated variants were significantly more frequent among RSV-B than RSV-A (9.8% vs 0.5%; p&#xa0;<&#xa0;0.001). CONCLUSION: Most substitutions that were detected within the nirsevimab antigenic site reflect ongoing natural RSV evolution and do not significantly affect nirsevimab susceptibility. However, detection of resistance-associated variants highlights the importance of continuous genomic and phenotypic surveillance.

Humans↗
PubMed1979

Analysis of HLA-D region-associated molecules with monoclonal antibody.

A group of monoclonal antibodies directed against nonpolymorphic HLA-D antigens (human Ia antigens) was produced by somatic cell hybridization. One of these antibodies was used to analyze the two-dimensional polyacrylamide gel electrophoretic pattern of the HLA-D alloantigens from different HLA-D homozygous B-cell lines. Two-dimensional gels of [35S]methionine-labeled cell extracts immunoprecipitated by a monoclonal antibody directed against HLA-D antigens showed a complex set of spots whose electrophoretic pattern varied according to the HLA-D type. The major HLA-D-related electrophoretic polymorphism was found in the basic and smaller (26,000-28,000 daltons) HLA-D polypeptides. These patterns represent allele-specific "fingerprints" of different HLA-D genotypes. There are striking similarities with respect to number, size, and charge spectrum among HLA-D polypeptides and the murine I-A and I-E subregion polypeptides, suggesting a similar genetic organization and molecular complexity in both species.

Cell Line↗
PubMed1979

A human thymus-leukemia antigen defined by hybridoma monoclonal antibodies.

A series of mouse hybridomas producing monoclonal antibodies against human acute lymphocytic leukemia (ALL) cells was generated and screened for tumor specificity. Among 1200 primary cultures, 60 produced an antibody that could distinguish between the immunizing leukemia cells and an isologous B lymphoblastoid cell line. Of these, two produced an antibody that detects an antigen expressed preferentially on ALL cells and on a subpopulation of normal cells found in the cortex of the thymus. Other normal human lymphoid cells from lymph nodes, spleen, bone marrow, and peripheral blood express only low levels of this antigen. High levels of this "thymus-leukemia" antigen were found on T-ALL cells, T-ALL-derived cell lines, and some "null" ALL cells. By contrast, B-cell leukemias, B lymphoblastoid cell lines, and normal and malignant myeloid cells contain either low or undetectable amounts of this antigen. The thymus-leukemia antigen has been isolated from the membranes of leukemia cells by detergent solubilization and subsequent immunoprecipitation with the monoclonal antibody. Preliminary biochemical characterization shows the antigen to be associated with a polypeptide of Mr approximately 28,000.

Antibody Specificity↗
PubMed1978

Antigenic drift in influenza A viruses. I. Selection and characterization of antigenic variants of A/PR/8/34 (HON1) influenza virus with monoclonal antibodies.

Antigenic variants of A/PR/8/34 [HON1] influenza virus were selected after a single passage of the parent virus in embryonated chicken eggs in the presence of monoclonal antibodies to this virus. The monoclonal antibodies were produced by a hybridoma and were specific for an antigenic determinant on the HA molecule of the parent virus. Seven antigenic variants were analyzed with 95 monoclonal anti-HA antibodies prepared in vitro in the splenic fragment culture system. Three subgroups of antigenic variants were distinguished. The antigenic changes were primarily recognized by monoclonal antibodies to the strain- specific determinants of the parental hemagglutinin (HA) molecule. Monoclonal antibodies to HA determinants shared (in an identical or cross-reactive form) by parental virus and more than three heterologous viruses of the HON1 and H1N1 subtypes were unable to recognize the antigenic change on the variants. Similarly, heterogeneous antibody preparations could not differentiate between parental and variant viruses. The results are compatible with the idea that the HA of PR8 has available a large repertoire of antigenic modifications that may result from single amino acid substitutions, and that antigenic changes can occur in the strain- specific determinants on the HA molecule in the absence of concomitant changes in the cross-reactive HA determinants. The findings suggest that antigenic drift, in order to be epidemiologically significant, probably requires a series of amino acid substitutions in, or close to, the antigenic area on the HA molecule.

Antibodies, Viral↗
PubMed1977

The in vitro antibody response to cell surface antigens. II. Monoclonal antibodies to human leukemia cells.

A method has been developed for the production of monoclonal mouse antibody responses in vitro against human cell surface antigens. Limiting numbers of immune spleen cells were transferred to syngeneic, irradiated recipients whose spleen fragments were then cultured in vitro and stimulated to produce antibody. The majority of the antibody from any one fragment culture was likely to be the product of a single donor B cell and thus monoclonal. Evidence for this included a linear relationship between donor cell transferred and spleen fragments producing antibody, extremely restricted isoelectric focusing patterns of the individual antibody products, and unique reactivity patterns of these antibodies against a panel of human lymphoid cells. Different human B leukemia cells were seen as immunogenically distinct by the mouse. By using the monoclonal mouse antibodies as probes, a fine analysis of cell surface antigens is jow possible.

Animals↗
PubMed2026

A CHO-Derived Matrix Attachment Region Enhances Transgene Dosage, SATB1 Recruitment, and Monoclonal Antibody Expression in a Dual-Promoter Vector System.

The production of monoclonal antibodies (mAbs) in Chinese hamster ovary (CHO) cells is often affected by position-effect variegation and the gradual loss of transgene expression over time. Hence, we have designed a dual-promoter IgG expression vector and compared versions that either contained or lacked a CHO-derived matrix-attachment region (MAR). Stable CHO-S pools, cultured in serum-free conditions, revealed that the MAR-containing construct produced higher and more consistent antibody levels across ten passages, as confirmed by Western blot and Protein A Octet analysis. Product-quality analysis by size-exclusion chromatography and reducing SDS-PAGE confirmed formation of properly assembled, mainly monomeric antibodies in both cases. Quantitative PCR indicated greater transgene copy numbers in MAR pools (+&#x2009;48% for the light chain and&#x2009;+&#x2009;71% for the heavy chain), and RT-qPCR showed roughly fourfold higher transcript levels for both chains relative to controls. Bioinformatic analysis revealed several SATB1 binding motifs within the MAR sequence, and ChIP-qPCR demonstrated SATB1 association with the MAR-linked transgene locus. Overall, the data suggested that a CHO-native MAR could enhance transgene dosage and transcriptional activity, while preserving product integrity, possibly through SATB1-mediated chromatin organization. Ongoing work includes chromatin-mark profiling and process-level productivity measurements to better define the impact of MAR-based vector design on biomanufacturing performance.

Animals↗
PubMed1979

Characterization of a monoclonal antibody directed against mouse macrophage and lymphocyte Fc receptors.

To investigate the antigenic relationship between the macrophage and lymphocyte Fc receptors (FcR), a monoclonal antibody capable of blocking mouse macrophage Fc receptors was selected. Hybrids were formed by fusing the P3U1 mouse myeloma and spleen cells from a rat immunized with the mouse macrophage-like cell lines J774 and P388D1. The Fab fragment of the monoclonal IgG secreted by clone 2.4G2, inhibited the trypsin-resistant Fc receptor II (FcRII), which is specific for immune aggregates of mouse IgG1 and IgG2b, but had no inhibitory effect on the trypsin-sensitive Fc receptor I (FcRI), which binds monomeric IgG2a and erythrocytes coated with IgG2a. Thus, the monoclonal 2.4G2 IgG appeared to be specific for macrophage FcRII. Further evidence that the 2.4G2 IgG was directed against FcRII came from binding studies of the monoclonal antibody to J774 cells and a series of independently isolated variants which do not express FcRII. These variants of J774 bound 5% as much of the monoclonal antibody as the parent line, which bound 600,000 molecules of 2.4G2 IgG per cell. The antigenic relatedness of mouse lymphocyte FcR to mouse macrophage FcRII was demonstrated by the binding of 2.4G2 IgG to FcR-bearing lymphoid cell lines and the inhibition of the lymphocyte FcR by the monoclonal antibody. Preincubation of spleen cells and peritioneal cells with 2.3G2 IgG likewise inhibited rosette formation with ox erythrocytes coated with rabbit IgG. The ability of the hybridoma IgG to inhibit mouse FcRII was independent of the major histocompatibility complex. The 2.4G2 IgG antigenic determinant was not present on rat, guinea pig, rabbit, or human FcR-bearing cells.

Animals↗
PubMed2026

Hex-MASP for mapping the whole-tissue spatial proteome and the intrabrain distribution of monoclonal antibodies.

Whole-tissue level spatial proteomics provides critical insights into region-specific biological regulations but remains challenging. Previously, we introduced the micro-scaffold assisted spatial proteomics (MASP) concept for whole-tissue mapping. However, this prototype required substantial development in spatial resolution, practicality, and throughput for practical application. Here we present a next-generation MASP technique (hex-MASP) featuring i) a new design of hexagonal-micro-wells fabricated with optimized projection micro-stereolithography 3D-printing, achieving high spatial resolution, sampling robustness, and mechanical strength for reproducibly compartmentalizing even tough tissues; ii) enhanced throughput/effectiveness in sample preparation and LC-MS analysis with high quantitative quality. Applied to mouse brain, hex-MASP achieved in-depth, whole-tissue mapping for >6,000 proteins in mouse brains, with high spatial accuracy and excellent data quality. The substantially improved resolution revealed critical regional details across the entire brain, that were not previously captured, enabling precise depiction of protein distribution heterogeneity. This technique enabled the identification of many unreported regionally enriched proteins across brain structures. We further applied hex-MASP to investigate the intrabrain distribution of intracerebroventricularly dosed antibody therapeutics and related proteins, which enabled whole-tissue mapping of protein drugs revealed insights into antibody brain penetration and distribution. Hex-MASP represents a robust, scalable platform for whole-tissue spatial proteomics.

Animals↗
PubMed1978

Monoclonal antibodies against rabies virus produced by somatic cell hybridization: detection of antigenic variants.

Somatic cell hybrids (hybridomas) between mouse myeloma cells and spleen cells derived from BALB/c mice immunized with inactivated rabies vaccine were found to produce antibodies to rabies virus. Monoclonal antibodies with different specificities were obtained either from the mass culture directly after fusion or from clones derived from a single-cell cloning procedure. Several strains of fixed or street rabies virus were analyzed by virus neutralization procedures which demonstrated differences in their antigenic composition. Hybridoma antibodies were able to protect experimental animals from lethal rabies virus infection.

Antibodies, Viral↗
PubMed1979

Monoclonal antibodies reacting with murine teratocarcinoma cells.

Monoclonal antibodies were produced in vitro by fusing mouse myeloma cells with spleen cells from a rat immunized with the C3H mouse teratocarcinoma C86-S1. After the fusion two clones were chosen for further analysis. The first clone, 3C4-10, produced an antibody recognizing an antigen with a distribution restricted to teratocarcinoma cell lines, an endoderm cell line, and a neuroblastoma. The second clone, 4A1-9, produced an antibody that reacted with all cultured murine cells tested and adult brain. Neither antibody reacted with preimplantation embryos. The 3C4-10 antibody recognized an antigen associated with proteins. The apparent molecular weight of the 3C4-10 antigen was greater than 100,000.

Animals↗
PubMed1979

Properties and applications of monoclonal antibodies directed against determinants of the Thy-1 locus.

Fusion of cells of the mouse myeloma line, P3/X63-Ag8 with spleen cells from AKR/J mice immunized against C3H thymocytes or from (BALB/c x BALB.K)F1 mice immunized against AKR/J thymocytes gave rise to hybrid cell lines that continuously secrete antibodies specific for the Thy-1.2 and Thy-1.1 antigens, respectively. Monoclonal antibodies from four such cell lines were analyzed in detail. All were 19S IgM, and, in the presence of complement (C), had high lytic titers on T cells of the appropriate antigenicity. Their specificity was shown by lysis of thymocytes from Thy-1 congenic mouse strains, A/J(Thy-1.2) and A. Thy 1.1. Furthermore, they lyse only 60 to 70% of lymph node cells, suggesting cytotoxicity for mature T cells and not B cells. Treatment of peripheral lymphocyte populations with monoclonal antibody plus C eliminated effector cytotoxic T lymphocytes, their precursors, and the mitogenic response to Con A, but did not affect the response to LPS. Purified, fluorescein-labeled monoclonal anti-Thy-1 antibody could be used to distinguish T and B cells. Purified antibody coupled to Sepharose 6MB was used to separate viable T and B cells. Two independently isolated anti-Thy-1.2 hybridomas are indistinguishable and bind the same determinant whereas a third is unique and may bind a separate site.

Animals↗
PubMed1978

Interspecies spleen-myeloma hybrid producing monoclonal antibodies against mouse lymphocyte surface glycoprotein, T200.

A cell hybrid has been selected from fusion of a mouse myeloma and rat spleen cells immunized against mouse lymphoma cells that produces monoclonal antibody against the mouse lymphocyte surface glycoprotein, T200. Antibody binding assays employing the monoclonal antibody show that there are about 50,000-100,000 molecules of T200 glycoprotein on mouse thymocytes and that similar antigens are present on spleen and bone marrow but not detected on nonlymphoid tissues. Examination of the labeled molecules precipitated from detergent extracts of spleen cells and thymocytes iodinated by the lactoperoxidase technique by SDS-PAGE confirm that there are structural differences between the antigens found on B and T lymphocytes. The B-cell glycoprotein consists of at least one component of apparent mol wt 220,000 on SDS-PAGE, while the T-cell glycoprotein has an apparent mol wt of about 190,000.

Animals↗
PubMed1978

T-lymphocyte heterogeneity in the rat: separation of functional subpopulations using a monoclonal antibody.

W3/25 antibody is the monoclonal product of a hybrid cell resulting from the fusion of a mouse myeloma cell line with spleen cells from a mouse immunized with rat thymocytes. Pure clones have been derived, and segregants free of parental myeloma chains have been isolated. Previous studies have shown that this antibody recognizes a subpopulation of T cells among rat thoracic duct lymphocytes. In the work reported here, three T-cell functions were assayed after separating rat thoracic duct lymphocytes on the fluorescence-activated cell sorter on the basis of labeling with W3/25 antibody. Two of the functional activities appeared to be completely segregated by this procedure. Thus, helper cell activity for an anti-hapten plaque-forming cell response was confined to the labeled population, whereas the allogeneic suppressive effect produced in a parental vector F1 adoptive transfer was mediated by cells in the unlabeled fraction. The third function, graft-versus-host activity, was almost entirely contained within the labeled subpopulation. It is concluded that the antigenic determinant recognized by the monoclonal antibody W3/25 is a differentiation marker for T-cell functional subpopulations.

Animals↗
PubMed2025

Nebulization of an mRNA-encoded monoclonal antibody for passive immunization of foals against Rhodococcus equi.

Inhalation of Rhodococcus equi causes severe pneumonia in humans and animals worldwide, most commonly affecting horse foals. The standard for preventing R. equi pneumonia in foals is transfusion of hyperimmune plasma, which is expensive and carries the risk of adverse effects. Our goal was to passively immunize foals against R. equi by nebulizing mRNA encoding an equine monoclonal antibody (mAb) against the virulence-associated protein A (VapA) directly into the lungs. VapA-specific memory B cells from an immunized horse were used to identify and select the sequence for an equine immunoglobulin (Ig)G1 mAb. In vitro-transcribed mRNA encoding this sequence expressed full-length, VapA-specific mAbs in vitro and safely and effectively produced intrapulmonary mAb in foals for at least 5 days following nebulization. These findings establish a platform to generate mRNA-encoded mAbs for immunotherapeutic and immunoprophylactic applications in horses and demonstrate the feasibility of delivering nebulized mRNA-mAb for intrapulmonary mAb expression in neonates.

Animals↗