Differential distribution of mouse polymeric immunoglobulin receptor (mpIgR): Establishment of enzyme-linked immunosorbent assay system for mpIgR

In spite of the relevance of the mouse as an experimental animal for immunological research, there is no specific monoclonal antibody (MoAb) against mouse polymeric immunoglobulin receptor (mpIgR) molecule. The aim of this study was to generate MoAb against mpIgR and to develop an enzyme-linked immunosorbent assay (ELISA) system. For this purpose, a mammalian expression vector encoding the extracellular part of mpIgR cDNA (also known as mouse free secretory component: mfSC) was injected into rats and mice. Specific responses were induced in both animals. The lymphocytes were collected from immunized mice and fused with myeloma cells to establish hybridomas secreting a MoAb against mpIgR. The purified MoAb reacted with mpIgR specifically and could be used in several biochemical and morphological experiments, such as Western blotting, immunoprecipitation and cell staining. By combining the two different MoAb, clone No.7 and No.19, which recognize different epitopes on the mpIgR molecule, a sandwich ELISA system was established. With this system, the pIgR concentrations in homogenates of several different mice organs were estimated. As a result, the homogenates of the small intestine were shown to contain higher amounts of pIgR compared with those from the large intestine, the liver or the kidney. These results indicated a differential distribution of the mpIgR molecule along the intestinal tract. This ELISA system should expand our knowledge about the mucosal immune system in mice.