A simple in vitro method for raising monoclonal antibodies to cochlear proteins

A Nobel-Winning Scientist: Aziz Sancar and the Impact of his Work on the Molecular Pathology of Neoplastic Diseases

Aziz Sancar, Nobel Prize winning Turkish scientist, made several discoveries which had a major impact on molecular sciences, particularly disciplines that focus on carcinogenesis and cancer treatment, including molecular pathology. Cloning the photolyase gene, which was the initial step of his work on DNA repair mechanisms, discovery of the "Maxicell" method, explanation of the mechanism of nucleotide excision repair and transcription-coupled repair, discovery of "molecular matchmakers", and mapping human excision repair genes at single nucleotide resolution constitute his major research topics. Moreover, Sancar discovered the cryptochromes, the clock genes in humans, in 1998, and this discovery led to substantial progress in the understanding of the circadian clock and the introduction of the concept of "chrono-chemoterapy" for more effective therapy in cancer patients. This review focuses on Aziz Sancar's scientific studies and their reflections on molecular pathology of neoplastic diseases. While providing a new perspective for researchers working in the field of pathology and molecular pathology, this review is also an evidence of how basic sciences and clinical sciences complete each other.

Characterization of Human Tissue Factor (TF)–Specific Monoclonal Antibodies Prepared Using a Rapid Immunization Protocol

Tissue factor (TF) plays an important, physiological role in hemostasis. Recent studies have demonstrated the over-expression of TF in a number of solid tumor types and its pathological roles in angiogenesis and tumor metastasis. In this study, we report the development and characterization of a panel of murine MAbs that are specific for human TF, but do not inhibit TF-mediated blood coagulation. By using a modified repetitive immunizations at multiple sites (RIMMS) protocol in conjunction with an efficient hybridoma cloning procedure, anti-TF MAbs were generated within a relatively short time frame of 5-6 weeks. Following primary screening by ELISA, the binding of the MAbs to the native form of human TF was demonstrated in flow cytometry using a stable cell line expressing human TF. Several of these TF-specific MAbs did not inhibit blood coagulation in a blood coagulation assay and bound with high affinity (0.5-2 nM) to human TF in BIAcore analyses. Importantly, this study represents an independent evaluation of the RIMMS strategy for MAb generation and demonstrates that class-switched, high-affinity MAbs can be generated rapidly and reliably using RIMMS.

A library of bacteriophage-displayed antibody fragments directed against proteins of the inner ear

Bacteriophage display of antibodies provides a method for the generation of immunological reagents against rare and uncharacterized antigens. To ascertain the usefulness of this approach for the characterization of inner-ear proteins, we produced a bacteriophage-displayed antibody-fragment library directed against proteins from the bullfrog's sacculus. This library was probed for bacteriophage that bound to proteins present in a lysate of hair cells, the sensory receptors of the inner ear. The predominant bacteriophage clone after selection expressed an antibody fragment that recognized a single protein in the inner ear. This antigen occurred in both the nonsensory and sensory epithelia of the sacculus. The specificity of the antibody fragment indicates that our bacteriophage-displayed library provides a useful source of immunological tools that should facilitate the identification and biochemical characterization of novel proteins in the inner ear.

A sugar transporter as a candidate for the outer hair cell motor

Forces developed by cochlear outer hair cells (OHCs) are responsible for the sharp tuning that underlies sensitivity and frequency selectivity in the ear. OHCs exhibit a voltage-dependent motility involving a 'motor' protein embedded in the basolateral membrane. The motor has so far resisted molecular identification. Here we provide evidence that it may be related to a fructose transporter. We show that OHCs are able to transport this sugar selectively and that the sugar alters electrical properties of the OHC motor. These data can be combined into an integrated model of a sugar carrier, that makes the novel prediction, demonstrated here, that such 'neutral' transporters can be voltage dependent.

Rapid development of affinity matured monoclonal antibodies using RIMMS

Affinity matured murine monoclonal antibody producing cell lines can now be rapidly generated using a novel repetitive, multiple site immunization strategy designated RIMMS. RIMMS capitalizes on rapid hypermutation and affinity maturation events which occur in B cell populations localized within secondary lymphatic tissue early in response to antigenic challenges. A murine myeloma cell line, P3XBcl-2-13, stably transfected with Bcl-2, enhances the outgrowth of hybridomas following somatic fusion with immune lymphocytes isolated from pooled peripheral lymph nodes (PLN) 8-14 days after the initial immunization. Immunizations somatic fusion, screening and isolation of affinity matured IgG secreting monoclonal antibody cell lines occur within a one month time period. By using RIMMS, we have been able to expedite the isolation of affinity matured monoclonal antibodies to numerous antigens, including a drug hapten.

Monoclonal antibody markers for early development of the stereociliary bundles of mammalian hair cells

Two monoclonal antibodies, SC1 and SC2, were raised in vitro against antigens from the stereocilia of guinea-pig hair cells. They both labelled stereociliary antigens that were not detected in any other cell within the cochlear duct or the vestibular epithelial. SC1 cross-reacted with the tectorial membrane in the cochlea and labelled both cochlear and vestibular hair cells from both the mouse and the rat. In the mouse the SC1 antigen was labelled from embryonic days 16-18, coincident with the development of the stereociliary bundles. SC1 cross-reacted with neuromuscular junctions from striated muscle and with basal keratinocytes in skin. SC2 did not cross-react cleanly with hair cells from the mouse or the rat but it cross-reacted with proximal tubules of the guinea-pig kidney. Both antibodies can be used as cellular markers within the guinea-pig cochlea and SC1 should be particularly useful for studies of hair cell differentiation in the mouse.

In vitro immunization: generation of neutralizing monoclonal antibodies to human interleukin-10

The potential of the in vitro immunization technique to evoke an immune response against an immunomodulatory protein was evaluated using, as antigen, human interleukin-10 (IL-10), a novel cytokine with pleiotropic effects on human and murine lymphocytes and macrophages. After pre-priming the support cells for 48 h and subsequent 3-day stimulation of splenocytes from a non-immune BALB/c mouse with recombinant human IL-10 (rhIL-10; 2 micrograms/ml), significant stimulation of splenocytes was observed. 7 days after fusion with the non-secreting myeloma line X63/Ag8.653, IL-10-specific antibodies were detected by ELISA and dot blot in more than 70% of the hybridoma supernatants. After limiting dilution of the hybridoma cells showing IL-10-neutralizing activity in a bioassay using murine MC/9 mast cells, the isotype of the monoclonal antibodies (mAbs) obtained was 20% IgM, 16% IgG and 6% IgA. All other antibodies elicited IgM as well as IgG isotypes. The neutralizing activity of the specific mAbs tested was dose-dependent. Our results show that in vitro immunization can be employed successfully to generate functional mAbs to immunomodulatory proteins, even if these exhibit cross-species activity.

Monoclonal antibodies specific for endoplasmic membranes of mammalian cochlear outer hair cells

Monoclonal antibodies were raised in vitro against an antigen associated with the lateral cisternal membranes of outer hair cells. Two of the antibodies were class IgM and one of these retained its specific reactivity in tissue fixed with aldehydes and embedded in the resin LR White. Immunogold labelling for electron microscopy showed that the antigen was closely associated with the membranes rather than the cytoplasmic or lumenal regions of the cisternae. The third antibody was an IgG. All three weakly labelled a protein band with an apparent molecular weight of about 60 kD on a Western blot. The antibodies did not cross-react with any other cell in the organ of Corti, including the inner hair cells. Furthermore, they showed no cross-reactivity with skeletal muscle, kidney, gut, brain, skin, blood or retina from the guinea pig. The results suggest that the lateral cisternae in outer hair cells may be functionally different from those of inner hair cells. The antibodies may provide useful markers for outer hair cells in studies of hair cell regeneration.