Specific pancreatic β-cell surface antigens recognized by a xenogenic antiserum
Summary, in English
An antiserum (R4) from a rabbit immunized with suspensions of C57BL/6J ob/ob mouse islet cells contains antibodies which in a 125I-protein A radioligand assay can be demonstrated to bind to single cell suspensions of normal Naval Medical Research Institute (NMRI) mouse islet cells. The binding of 125I-protein A to islet cells was about four times that of normal rabbit serum (NRS) after incubation at a 1/600 dilution of R4 antiserum quantitatively absorbed to mouse spleen lymphocytes (R4A antiserum) and hepatocytes. Subsequent absorption of the R4A antiserum to islet cells significantly reduced the binding of 125I-protein A to islet cells incubated with the doubly absorbed serum. Immunoprecipitation of radiolabeled islet cell lysates followed by SDS polyacrylamide gel electrophoresis and autoradiography suggested that the R4A antiserum recognized a Mr 40,000 glycoprotein. This glycoprotein was not detected in spleen lymphocytes. Electron microscope detection of gold-protein A complexes suggested that the binding of islet cell surface antibodies was cell specific. Islet cell suspensions incubated with R4A antiserum and gold-protein A showed that 86 ± 3 gold particles were bound per 100 β-cells (mean ± SE for six experiments). In contrast, the number of gold particles per 100 endocrine non-β-cells was 8 ± 1 which was similar to the number achieved with NRS (3 ± 1) on all endocrine islet cells. Our observations suggest that the pancreatic islet cells, in particular the β-cells, express a specific antigen.
- ISSN: 0021-9525