The use of in vitro immunisation, as an adjunct to monoclonal antibody production, may result in the production of hybridomas secreting polyreactive antibodies

Generation of Mouse Monoclonal Antibodies Specific to Chikungunya Virus Using ClonaCell-HY Hybridoma Cloning Kit

Monoclonal antibodies offer high specificity and this makes it an important tool for molecular biology, biochemistry and medicine. Typically, monoclonal antibodies are generated by fusing mouse spleen cells that have been immunized with the desired antigen with myeloma cells to create immortalized hybridomas. Here, we describe the generation of monoclonal antibodies that are specific to Chikungunya virus using ClonaCell-HY system.

Polyreactivity of monoclonal antibodies made against human erythrocyte membranes with various pathogenic bacteria

Glycophorins comprise the major sialoglycoproteins of the human erythrocyte membrane. Several years ago we described a murine monoclonal antibody (MAb), designated 124,D-7 (IgM), developed by in vitro immunization with human erythrocyte membranes as antigen. We found the MAb reacted with a neuraminidase-dependent epitope on glycophorin A. Recent findings using ELISA with various bacteria as coating antigens have demonstrated strong cross-reactions of MAb 124,D-7 with some bacteria like Legionella and no reaction with bacteria such as Streptococcus pneumoniae. A second MAb, 130,E-4 (IgM), generated by the in vitro immunization technique, agglutinated human red cells irrespective of blood groups. This MAb showed strong cross-reactions with bacteria different from those being positive with MAb 124,D-7. The broad cross-reactivities of the two MAbs suggested that they are polyreactive antibodies. Sequencing of the V(H) and V(L) genes of MAb 124,D-7 showed germ-like sequences characteristic of polyreactive antibodies. The nucleotide sequences of the V(H) and V(L) genes of MAb 124,D-7 matched sequences coding for antibodies against CD34 and cross-reacting streptococcal antibodies. For Legionella pneumophila, the main interacting band on immunoblots was identified as the major outer membrane protein by mass spectrometry after separation by isoelectric focusing followed by SDS-PAGE. Flow cytometry showed that the epitope for MAb 124,D-7 was not displayed on live L. pneumophila but became exposed after heat treatment. Studies with one of the control MAbs, 145,F-2, directed against phosphorylcholine, which is known to be present on erythrocytes and some bacteria, showed that the epitope is deeply buried in the human erythrocyte membrane as neither neuraminidase nor papain exposed the epitope. The positive control MAb 3/1 directed against an epitope on LPS of L. pneumophila revealed weak cross-reactions with Pseudomonas aeruginosa.

Surface plasmon resonance imaging detection of silver nanoparticle-tagged immunoglobulin

The detection sensitivity of silver nanoparticle (AgNP)-tagged goat immunoglobulin G (gIgG) microarrays was investigated by studying surface plasmon resonance (SPR) images captured in the visible wavelength range with the help of a Kretchmann-configured optical coupling set-up. The functionalization of anti-gIgG molecules on the AgNP surface was studied using transmission electron microscopy, photon correlation measurements and UV-visible absorption spectroscopy. A value of 1.3×10(7) M(-1) was obtained for the antibody-antigen binding constant by monitoring the binding events at a particular resonance wavelength. The detection limit of this SPR imaging instrument is 6.66 nM of gIgG achieved through signal enhancement by a factor of larger than 4 owing to nanoparticle tagging with the antibody.

Antigen-Based Immunofluorescence Analysis of B-Cell Targeting: Advanced Technology for the Generation of Novel Monoclonal Antibodies with High Efficiency and Selectivity

On the basis of immunofluorescence analysis, an entire pathway of B-cell targeting was successfully identified, which can drive selective production of monoclonal antibodies with high efficiency and selectivity. The technique comprises three critical steps, antigen-based preselection of B lymphocytes, formation of antigenselected B lymphocyte and myeloma cell complexes, and selective fusion of B-cell-myeloma cell complexes with electrical pulses. Intriguingly, expression of surface immunoglobulin receptors on B lymphocytes was recognized even after immunization in vitro. The number of the antigen-selected B lymphocytes after in vitro immunization was in fact higher than that obtained after in vivo immunization, suggesting that such shortterm immunization is applicable for B-cell targeting. Immunofluorescence analysis revealed the targeting technique to demonstrate fivefold to tenfold higher efficiency for formation of hybridoma cells than a polyethylene glycol (PEG)-mediated method. This efficiency is in good agreement with production of hybridoma cells secreting desired monoclonal antibodies determined by an enzyme-linked immunosorbent assay (ELISA). The addition of a low concentration of PEG brought about enhanced fusion efficiency and reduced cell damage at even electric intensities as high as 4.0 kV/cm and 5.0 kV/cm. Here we demonstrate that immunofluorescence analysis can successfully clarify an entire pathway of B-cell targeting and provide advantages over the PEG-mediated method. This advanced technology may be applicable for rapid production of monoclonal antibodies based on in vitro immunization.