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Objectives: Recent interest has been expressed in rheumatic manifestations in hepatitis C virus (HCV)-infected populations. The aim of this study was to determine the prevalence and characteristics of the musculoskeletal manifestations and serological markers of autoimmunity in HCV-infected patients in Israel., Methods: Ninety anti-HCV-positive patients were consecutively interviewed and examined. The prevalence of autoantibodies and their association with rheumatologic symptoms were also determined., Results: Rheumatic manifestations were found in 28 subjects (31%), and included arthralgias (9%), arthritis (4%), cryoglobulinemia (11%), sicca symptoms (8%), cutaneous vasculitis (2%), polymyositis (1%), and antiphospholipid syndrome (1%). Rheumatic complications were not associated with liver disease severity, or subjects' gender. In addition, myalgia was reported by 22 patients (24%), and fibromyalgia was diagnosed in 14 (16%). Sixty-nine percent of the patients had at least one autoantibody detected in their serum, the most prevalent being rheumatoid factor (RF), 44%; antinuclear antibody (ANA), 38%; and IgM and IgG anticardiolipin antibodies (ac1), 28% and 22%, respectively. The frequency of autoantibodies was not associated with liver disease severity or rheumatic disorders., Conclusions: Musculoskeletal manifestations and autoimmune markers are common in HCV infection. An investigation of risk factors for HCV infection is pertinent in a patient presenting new rheumatic manifestations and should be included in the history of present illness. Future studies of these disorders may uncover the full spectrum of these associations and provide new insights into their operating mechanisms.

The present experiments were undertaken to delineate the role of LD and SD antigens in terms of memory in cell-mediated immune response (CML). Using recombinants that differ for either the H-2K or H-2D determinants (SD-different) and other recombinants differing for the central region of H-2 (LD-different), we have investigated this question. The results indicate that priming to SD determinants leads to a more rapid and higher response when cells are restimulated in vitro with either the same SD antigen alone or the same SD plus an LD antigen and tested on target cells that possess either the SD antigen alone or both the LD and SD antigen. Antigens in the central regions of H-2, which includes LD, serve as the stimulus both for the helper T cells and for the cytotoxic T lymphocytes. Priming with a high dose of LD antigens leads to memory in the cytotoxic T lymphocyte recognizing the cytotoxic target antigens coded by the central region of H-2. Nevertheless, memory could not be detected when priming was done under the same conditions as for SD antigens. Moreover, a primed helper T-cell response does not facilitate the development of increased CML on restimulation in vitro with the LD antigen used for priming and a new SD antigen. Thus, it seems that memory in CML is in the cytotoxic T lymphocyte and not in the proliferating helper cells.

Tolerance was induced against cytotoxic target determinants coded for by genes of the I region. Neonatal recipients were immunized with high doses of cells from an I region incompatible donor. Nonreactivity in adult life did not reflect extensive donor cell chimerism, since the great majority of cells in spleens of animals rendered tolerant were of host phenotype. Although specific nonresponsiveness in CML could be induced by these protocols, the MLC proliferative response was in most cases still present alghough very much decreased. In only a very occasional animal was complete nonreactivity in MLC seen. The nonresponse in CML was paralleled by acceptance of thyroid allografts as measured by radioactive iodine incorporation and morphological studies.

The LD and SD antigens of the major histocompatibility complex subserve differential roles in the induction of the proliferative phase in mixed lymphocyte culture and in the cytotoxic reaction seen in cell-mediated lympholysis. The present study suggests that they also behave differently in the neonatal induction of tolerance. SD antigens appear to induce tolerance in the cytotoxic T lymphocytes very effectively, whereas LD antigens (or the cytotoxic targets coded by genes in the I and/or S regions) are relatively ineffective in this regard. LD antigens presented neonatally are effective at inducing tolerance in the proliferating helper cells.