Search

The capacity of normal human T lymphocytes to form rosettes with sheep red blood cells can be inhibited by drugs or agents which induce elevations in intracellular levels of cyclic AMP. The effect is early in the presence of agents which elicit rapid elevations in intracellular cyclic AMP (isoproterenol, aminophylline) and occurs later in the presence of cholera toxin which induces a dalayed increase in endogenous cyclic AMP. Dibutyryl cyclic AMP is inhibitory, and the effects of dibutyryl cyclic AMP and the adenyl cyclase stimulators are potentiated by inhibition of phosphodiesterase. These data provide substantial evidence that elevation of intracellular cyclic AMP diminishes E rosette function of lymphocytes.

Factor VIII coagulant activity (VIIIC) and the von Willebrand's disease antigen (Factor VIII-like antigen, vW-Ag) are biologically linked, and it has been suggested that they reside on the same molecule. However, insolubilized human isoantibody to VIIIC and rabbit antiserum containing antibodies to VIIIC and vW-Ag differentially bind and remove these entities from plasma, thus physically segregating one from the other. These findings indicate that Factor VIII coagulant activity resides on a molecule distinct from that expressing the von Willebrand's antigen.

The pathogenetic mechanism involved in a form of experimental allergic glomerulonephritis induced by immunization of rats with renal tubular antigen has been investigated. A single immunization with less than a milligram of a crude renal tubular preparation, probably containing less than 25 µg of the specific nephritogenic antigen, is effective in the induction of this form of chronic membranous glomerulonephritis. In the nephritic kidney autologous nephritogenic tubular antigen is found in the glomerular deposits along with γ-globulin and complement. When large amounts of antigen are injected during induction of the disease the exogenous immunizing antigen can also be detected in the glomerular deposits. It appears that this disease results from the formation of circulating antibodies capable of reacting with autologous renal tubular antigen(s) and the deposition of these antibodies and antigen(s) plus complement apparently as immune complexes in the glomeruli. This pathogenetic system has been termed an autologous immune complex disease and the resultant glomerulonephritis has been similarly designated.

The nephritogenic antigen, responsible for the immunogenic stimulus in experimental allergic glomerulonephritis induced with tubular antigen, has been identified as a renal tubular epithelial (RTE)-specific antigen and has been isolated in a relatively purified form. This antigen, RTE-α5, is a distinct and antigenically specific lipoprotein of high density which is derived primarily from the brush border of proximal convoluted tubular epthelium of the rat kidney. It has been suggested that this molecule may be a plasma membrane subunit. Immunization of rats with as little as 3 µg N of RTE-α5 in complete Freund's adjuvant has effectively induced this form of membranous glomerulonephritis. RTE-α5 is not a constituent of normal rat glomeruli; however, with the onset of autologous immune complex nephritis it is deposited in a granular fashion along glomerular capillary walls indistinguishable from the deposits of γ-globulin and complement. The antigenic specificity of this antigen and its tissue derivation has been explored, and the observations support the autologous immune complex pathogenesis of the glomerulonephritis induced in rats by immunization with renal tubular antigen.

SH virus-associated antigens have been identified in the liver and blood by immunofluorescence. This antigenic expression of the hepatitis agent or its genome is found in the cytoplasm of hepatocytes and other cells of the liver. Acute hepatitis is associated with hepatocellular localization of SH antigen, whereas alternative or additional SH antigen in the cytoplasm of nonhepatocytes is observed in chronic or recurrent hepatitis. Persistent intrahepatic SH antigen has also been observed in conversion from acute to chronic hepatitis, and the persistence of this virus-associated antigen in the liver may serve a significant pathogenetic role in mediating direct anti-tissue responses as well as local immune complex reactions. Competitive inhibition studies of SH antigen suggest at least two antigenically and sterically independent determinants on the SH particle.