PubMed · 4775619
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R Armas Cruz. 1973. [Various comments on autoimmunity].. https://pubmed.ncbi.nlm.nih.gov/4775619/
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Myelin basic protein (MBP)-specific T cells were isolated directly from peripheral blood by stimulation either with native MBPp85-99 or altered peptide ligands (APLs) in which substitutions of the lysine were made at position 93, a TCR contact residue. We report here that the APL 93A could alter the cytokine profile of some autoreactive MBPp85-99 reactive T cell clones, switching them from a Th0 phenotype secreting high concentrations of IL-4, IL-5, and IFN-gamma into Th2 cells secreting significantly less IFN-gamma. However, in vitro stimulation with the 93A peptide, in some instances, induced T cells that responded better to the native MBPp85-99 peptide. Functionally, the APL 93A was shown to act as an antagonist for IFN-gamma secretion. Based on TCR sequencing and single cell cloning, this alteration in cytokine profile was determined to be the result of the differential activation of individual T cell clones. We discuss the implications of these data for the strength of signal model of T cell activation.
Acute as well as chronic infections by HBV and HCV can be associated with extrahepatic disease. As in liver disease of non-viral etiology, several extrahepatic manifestations can be observed that are non-specific for HBV or HCV, e.g. those clinical signs and symptoms frequently encountered when cirrhosis of the liver is present. In addition, distinct clinical conditions have been described in which the unterlying liver disease is specifically due to HBV or HCV infection. In chronic HBV infection, glomerulonephritis (of the membranous and of the membranoproliferative type) and polyarteritis nodosa have been observed. The pathogenesis of both conditions involves the deposition of circulating immune complexes. Although controlled trials are lacking, interferon therapy appears to be beneficial. The use of immunosuppressive drugs and of plasmapheresis should probably be limited to the initial phase of treatment. In chronic HCV infection, mixed cryoglobulinemia (and ensuing systemic vasculitis) is a frequent extrahepatic manifestation. The clinical presentation might include the presence of purpura, arthralgias, weakness and renal involvement. Nowadays, HCV can be regarded as the etiological agent of a form of mixed cryoglobulinemia formerly considered to be 'essential'. In addition, an association to lymphoma has been postulated recently. Interferon alpha has been used for treatment with similar response rates as those observed in HCV-infected patients without cryoglobulinemia. Interestingly, the antiviral activity of interferon, e.g. normalization of transaminases and loss of serum HCV RNA, was closely related to the beneficial effect on cryoglobulinemia. An association of Sjögren's syndrome and of porphyria cutanea tarda to HCV infection (though claimed before) remains questionable. Serological markers of autoimmunity, e.g. antinuclear antibodies or anti-LKM-1, are present in many patients with chronic HCV infection. The clinical relevance of this latter observation appears low however, particularly since the decision for interferon treatment is hardly influenced by their presence.