Effects of combined antiviral therapy on asymptomatic mixed cryoglobulinemia in naive patients with chronic hepatitis C virus infection: a preliminary study.

The clinical spectrum of mixed cryoglobulinemia embraces several manifestations: recurrent vascular purpura, weakness, arthralgia/arthritis, glomerulonephritis, peripheral neuropathies, and Raynaud's phenomenon. Mixed cryoglobulinemia is currently treated with steroids, low-antigen content diet, immunosuppressors, plasma exchange, and antiviral therapy, namely, alpha -interferon alone or, more recently, in association with ribavirin. In the present research, we verified the effectiveness of combined therapy with interferon and ribavirin on asymptomatic mixed cryoglobulinemia in naïve (never treated before) patients with chronic hepatitis C. We enrolled 50 consecutive patients, 31 males and 19 females, with chronic hepatitis C who showed a sustained response to combined antiviral therapy (interferon and ribavirin). Before treatment, cryoglobulins were detected in 25 subjects (50%). Only 1 of the 25 patients with asymptomatic mixed cryoglobulinemia had persistence of cryoglobulins at the end of the follow-up period. Unexpectedly, in 7 of 25 subjects without mixed cryoglobulinemia before treatment, cryoglobulins became detectable after antiviral therapy. Our present study first reports the onset of asymptomatic mixed cryoglobulinemia in hepatitis C virus patients after clearance of the virus from blood obtained with a combined antiviral treatment. Possible explanations are discussed. Our data also suggest that the appearance of a clinically evident mixed cryoglobulinemia cannot be excluded in this kind of subject.

Cl- regulates cryoglobulin structure: a new hypothesis for the physiopathological mechanism of temperature non-dependent cryoprecipitation.

Cryoglobulins are pathological cold-precipitable immunoglobulins associated with a number of infectious, autoimmune and neoplastic disorders. Patients, when exposed to low temperatures, show symptoms related to intravascular precipitation of such immunoglobulins. The formation of cryoaggregates induced by exposure to cold temperature is the key pathogenetic mechanism. The subsequent intravascular precipitation can account for some clinical signs of peripheral vasculitis, but fails to explain the precipitation of cryoglobulins in regions where no significant temperature changes take place. We studied, in vitro, the activity of different ions on temperature-dependent aggregation of cryoglobulins and found that the concentration of Cl- present in solution is the most important variable that controls the size and the rate of formation of aggregates, both at low temperature and at 37 degrees C. We suggest that chloride anion could be the most important factor involved in the pathogenesis of events in visceral regions, such as in the kidneys, where no temperature changes occur but where the local Cl- concentration changes to maintain blood electrolytic homeostasis and acid-basic equilibrium. Moreover, identification of a specific structural domain responsible for Cl- binding may provide new targets for drugs selectively designed to interfere with cryoglobulin aggregation.

Interference of rheumatoid factor activity by aspartame, a dipeptide methyl ester.

Circulating autoimmune complexes of IgM rheumatoid factors (RF) bound to the Fc portions of normal, polyclonal IgG antibodies are frequently present in humans with rheumatoid arthritis (RA). The sweet tasting methyl ester of L-Asp-L-Phe (aspartame or APM) was found to relieve pain and improve joint mobility in subjects with osteo- and mixed osteo/rheumatoid arthritis [Edmundson, A. B. and Manion, C. V. (1998). Clin. Pharmac. Ther. 63, 580-593]. These clinical observations prompted the testing of the inhibition by APM of the binding interactions of human IgM RFs with IgG Fc regions. The propensity of APM to inhibit IgM RF binding was assessed by competitive enzyme immunoassays with solid-phase human IgG. Ten RA serum samples and three purified monoclonal cryoglobulins, all of which had RF activity, were tested in this system. We found that the presence of APM significantly reduced the binding of IgM RFs. The inhibitory propensity of APM with monoclonal RF cryoglobulins was increased by the addition of CaCl(2) to the binding buffer. Similar inhibition of the binding of RA derived RFs to IgG was observed for Asp-Phe and its amidated derivative, indicating that the methyl ester is not required for APM's interaction with IgM antibodies. A human (Mez) IgM known to bind octameric peptides derived from the Fc portion of a human IgG(1) antibody was tested for binding of dipeptides by the Pepscan method of combinatorial chemistry. The relative binding constants of Asp-Phe and Phe-Asp were ranked among the highest values for 400 possible combinations of the 20 most common amino acids. Possible blocking interactions of APM were explored by computer-assisted docking studies with the model of a complex of an RF Fab with the Fc of a human IgG(4) antibody. Modeling of ternary immune complexes revealed a few key residues, which could act as molecular recognition sites for APM. A structural hypothesis is presented to explain the observed interference with RF reactivity by APM. Extrapolations of the current results suggest that APM may inhibit the binding of IgG in a substantial proportion of IgM RFs. Interference of RF reactivity, especially in RA patients, may alleviate the pain and immobility resulting from chronic inflammation of the joints.

Interference of rheumatoid factor activity by aspartame, a dipeptide methyl ester.

Circulating autoimmune complexes of IgM rheumatoid factors (RF) bound to the Fc portions of normal, polyclonal IgG antibodies are frequently present in humans with rheumatoid arthritis (RA). The sweet tasting methyl ester of L-Asp-L-Phe (aspartame or APM) was found to relieve pain and improve joint mobility in subjects with osteo- and mixed osteo/rheumatoid arthritis [Edmundson, A. B. and Manion, C. V. (1998). Clin. Pharmac. Ther. 63, 580-593]. These clinical observations prompted the testing of the inhibition by APM of the binding interactions of human IgM RFs with IgG Fc regions. The propensity of APM to inhibit IgM RF binding was assessed by competitive enzyme immunoassays with solid-phase human IgG. Ten RA serum samples and three purified monoclonal cryoglobulins, all of which had RF activity, were tested in this system. We found that the presence of APM significantly reduced the binding of IgM RFs. The inhibitory propensity of APM with monoclonal RF cryoglobulins was increased by the addition of CaCl(2) to the binding buffer. Similar inhibition of the binding of RA derived RFs to IgG was observed for Asp-Phe and its amidated derivative, indicating that the methyl ester is not required for APM's interaction with IgM antibodies. A human (Mez) IgM known to bind octameric peptides derived from the Fc portion of a human IgG(1) antibody was tested for binding of dipeptides by the Pepscan method of combinatorial chemistry. The relative binding constants of Asp-Phe and Phe-Asp were ranked among the highest values for 400 possible combinations of the 20 most common amino acids. Possible blocking interactions of APM were explored by computer-assisted docking studies with the model of a complex of an RF Fab with the Fc of a human IgG(4) antibody. Modeling of ternary immune complexes revealed a few key residues, which could act as molecular recognition sites for APM. A structural hypothesis is presented to explain the observed interference with RF reactivity by APM. Extrapolations of the current results suggest that APM may inhibit the binding of IgG in a substantial proportion of IgM RFs. Interference of RF reactivity, especially in RA patients, may alleviate the pain and immobility resulting from chronic inflammation of the joints.

Immune complex mediated vasculitis in hepatitis B and C infections and the effect of antiviral therapy.

Case reports of seven patients with vasculitis and past or present viral hepatitis infection are presented, including studies on circulating immune complexes (CICs) and cryoglobulins by sucrose density gradient centrifugation or gel filtration, before and after antiviral therapy. Three patients had unusual vasculitic manifestations: coronary, large vessel, and muscle vasculitis, respectively. All the patients had high levels of CICs by the above methods, but only two had CICs by the C1q binding and conglutinin methods. The CICs/ cryoglobulins contained HBV and/or HCV antibodies, antigens, and genome. The concentration of hepatitis antibodies in immune complex form was severalfold higher than in the free form in serum. In one patient, the HBs antigen was present only in the CICs and in another, only hepatitis antibodies (no antigen/genome) were present in the serum or the cryoglobulins. With antiviral therapy, six patients went into long-lasting remissions. There was a temporal relationship between the regression of the vasculitic lesions and the decline in the levels of CICs/cryoglobulins.

Prevalence of cryoglobulinemia in chronic hepatitis C virus infection and response to treatment with interferon-alpha.

Chronic hepatitis C virus (HCV) infection is associated with a variety of clinically important extrahepatic abnormalities. We have assessed the prevalence of cryoglobulinemia and of the clinical syndrome associated with it in patients with chronic HCV infection. We also have evaluated the clinical, serologic, and biochemical response to antiviral treatment with interferon-alpha (IFN-alpha). Eighty-one patients with chronic liver disease associated with HCV infection were included. Cryoglobulins were sought in the serum. All patients were examined carefully for clinical manifestations of cryoglobulinemia (e.g., palpable purpura, Raynaud's syndrome, arthritis, peripheral neuropathy, Sjögren's syndrome, glomerulonephritis). Antiviral treatment with IFN-alpha, at a dose of 3 to 5 million units, 3 times weekly, was given to 20 patients with cryoglobulinemia. Cryoglobulins were detected in 45.7% of patients. Signs and symptoms of the clinical syndrome associated with cryoglobulinemia were present in 12.3% of the entire group of patients (27% of the subgroup with detectable cryoglobulins). Patients with cryoglobulinemia were older (mean age, 56 +/- 15 vs. 44 +/- 16 years; p = 0.002) and had a higher rate of cirrhosis (48.6% vs. 18.2%, rate ratio = 4.26, 95% confidence interval = 2.11 to 8.58, p = 0.00005) compared to patients without cryoglobulinemia. Cryoglobulins disappeared from the serum in 13 (65%) of the 20 patients who were treated for 6 to 12 months with IFN-alpha. This effect was affiliated in most patients with resolution of the clinical findings associated with cryoglobulinemia and return of transaminases to normal levels. Recurrence of cryoglobulinemia was observed in two thirds of the patients who were observed after treatment with IFN-alpha. We conclude that cryoglobulins are present in 45.7% of patients with chronic HCV infection. Symptoms or signs or both associated with the presence of cryoglobulins develop in a high proportion (27%) of these patients. Antiviral treatment with IFN-alpha leads to resolution of both cryoglobulinemia and the symptoms associated with it in most patients who also show a biochemical response to antiviral treatment. Recurrence is frequent after treatment withdrawal.

Influence of fibronectin-containing blood products on lymphocyte reactivity.

Two fibronectin (FN)-containing blood products, human peripheral blood plasma and cryoprecipitate, were examined for their effect on mitogen-induced lymphocyte transformation in vitro. Responses of human peripheral blood lymphocytes to phytohemagglutinin (PHA) were depressed in the presence of a plasma concentration above that required for maximum DNA synthesis, and this concentration must be present in cultures prior to lymphocyte activation. The removal from the plasma of heparin-induced cryoprecipitate, a complex consisting of FN, heparin, and fibrinogen, resulted in a significant reduction in the inhibitory effect of the plasma on the PHA response. Plasma specifically depleted of FN by affinity chromatography on gelatin-agarose beads was 32 percent less inhibitory to the PHA-induced stimulation of cells than untreated plasma; the remaining inhibitory activity in the FN-depleted plasma samples was attributed to the presence of other normal immunosuppressive factors. The inhibitory capacity of FN in plasma was similar to that obtained with purified FN alone, which indicates that, unlike that of other known plasma inhibitors, the immunosuppressive activity of FN was not altered by the presence of other components of plasma. Cryoprecipitate used in the treatment of hemophilia contains high levels of FN, and, as anticipated, PHA-induced lymphocyte transformation was markedly depressed in the presence of solubilized cryoprecipitate. The contribution of FN to the T-cell abnormalities in patients chronically receiving cryoprecipitate and/or factor VIII concentrates derived from cryoprecipitate warrants further investigation.