Immunoglobulin double isotype-producing hybridomas isolated from an autoimmune (NZB x NZW)F1 mouse

Oral λ-carrageenan intake alleviates skin symptoms in a hapten induced atopic dermatitis-like model

Lambda carrageenan is a widely used food additive. It has been shown that its oral intake induces suppression of T cell proliferation and antibody-mediated and cell-mediated immune response in experimental animals. In this study, we estimated the effect of oral ingestion of 0.001% λ-carrageenan on trinitrochlorobenzen-induced atopic dermatitis model mouse. Oral carrageenan ingestion alleviated ear swelling of hapten challenged mice and significantly suppressed mast cell hyperplasia in the topical skin. Serological analysis revealed that the treatment suppressed total IgE and antigen-specific IgG, and also suppressed both allergy driving cytokine interleukin-4 and counter-acting cytokine interferon-γ levels. It is suggested that the oral ingestion of λ-carrageenan may suppress the immunological response to the allergen and might be useful to treat atopic dermatitis.

Carbohydrate Specificity and Isotypes of Monoclonal and Polyclonal Antibodies to Conjugated Tetrasaccharide, a Synthetic Analogue of Repeating Unit of Capsular Polysaccharide of Streptococcus Pneumoniae Serotype 14

We studied carbohydrate specificity and isotypes of antibodies to BSA-conjugated tetrasaccharide, a repeating unit of the capsular polysaccharide of Streptococcus pneumoniae serotype 14, in mouse polyclonal sera and hybridoma-synthesized products. Natural IgM antibodies to the tetrasaccharide containing epitopes similar to surface carbohydrate structures of mammalian and human cells in low titers were determined in native mouse serum by ELISA using biotinylated tetrasaccharide and synthetic capsular polysaccharide as the solid-phase antigens. Polyclonal sera to the conjugated tetrasaccharide contained IgM and all subclasses of IgG antibodies, which were detected in a higher titer when the biotinylated tetrasaccharide was used as a solid phase antigen compared to synthetic capsular polysaccharide. Monoclonal antibodies to S. pneumoniae serotype 14 tetrasaccharide were identified in an equivalent titer using either biotinylated tetrasaccharide or synthetic capsular polysaccharide. Monoclonal antibodies obtained in vitro belonged to IgM isotype and cross-reacted with secondary full-size IgG antibodies. In the serum of mice inoculated with hybridoma, IgM and IgG2a antibodies recognizing the tetrasaccharide epitope in the structure of synthetic capsular polysaccharide were simultaneously determined.

A mouse monoclonal antibody against Alexa Fluor 647

Fluorophores are essential tools in molecular and cell biology. However, their application is mostly confined to the singular exploitation of their fluorescent properties. To enhance the versatility and expand the use of the fluorophore Alexa Fluor 647 (AF647), we generated a mouse monoclonal antibody against it. We demonstrate its use of AF647 for immunoblot, immunoprecipitation, and cytofluorimetry.

Human IgG1/IgG3 cryoglobulin suggesting lack of allelic exclusion

Immunoglobulins undergoing cold-dependent precipitation are known as cryoglobulins. A type I cryoglobulin after Brouet et al. from serum of a patient with severe cutaneous vasculitis and membranoproliferative glomerulonephritis was purified by reversible temperature-dependent precipitation and analyzed using FPLC, Western blotting and peptide sequencing. The isolated cryoglobulin consisted of a single complex of a molecular weight of above 210kDa observed under non-reducing conditions in SDS-polyacrylamide gel electrophoresis (PAGE). Under reducing conditions, this complex resolved into three bands, two of which were reminiscent of Ig heavy (HC) chains and one of Ig-light chains (LC). The FPLC-purified type I cryoglobulin showed reversible precipitation analyzed by spectrophotometry. Delineation of the peptides involved in complex formation by immunoblot analysis and peptide sequencing revealed IgG3-V(H)4/Igkappa-VkappaIII/JkappaII and IgG1/V(H)3 molecules with evidence of somatic mutation. Coomassie blue-staining suggested that molar amounts of the IgG3-heavy chain were much higher than that of the IgG1-heavy chain. Treatment with SDS and boiling did not disrupt the unusually high molecular weight Ig complex. Pre-treatment of the cryoglobulin in 6M guadinium hydrochloride followed by gel filtration chromatography suggested covalent association of the IgG3, IgG1 and Igkappa molecules. Therefore, it might be that the cryoglobulin was produced by a single plasma B cell clone which passed immunological check-points in terms of B cell selection in the bone marrow in the absence of allelic exclusion, class switching and affinity maturation by somatic mutation.

Generation of sequence-specific, high affinity anti-DNA antibodies

By taking advantage of the extreme stability of a protein-DNA complex, we have obtained two highly specific monoclonal antibodies against a predetermined palindromic DNA sequence corresponding to the binding site of the E2 transcriptional regulator of the human papillomavirus (HPV-16). The purified univalent antibody fragments bind to a double-stranded DNA oligonucleotide corresponding to the E2 binding site in solution with dissociation constants in the low and subnanomolar range. This affinity matches that of the natural DNA binding domain and is severalfold higher than the affinity of a homologous bovine E2 C-terminal domain (BPV-1) for the same DNA. These antibodies discriminate effectively among a number of double- and single-stranded synthetic DNAs with factors ranging from 125- to 20,000-fold the dissociation constant of the specific DNA sequence used in the immunogenic protein-DNA complex. Moreover, they are capable of fine specificity tuning, since they both bind less tightly to another HPV-16 E2 binding site, differing in only 1 base pair in a noncontact flexible region. Beyond the relevance of obtaining a specific anti-DNA response, these results provide a first glance at how DNA as an antigen is recognized specifically by an antibody. The accuracy of the spectroscopic method used for the binding analysis suggests that a detailed mechanistic analysis is attainable.