Contribution of Hepatitis C Infection to a Large Cohort of Cryoglobulin-Positive Patients: Detection and Characteristics

Sequential central retinal artery occlusions associated with cryoglobulinemia

BACKGROUND

Cryoglobulinemia, the presence of serum cryoglobulins which are immunoglobulins or complement components that precipitate at temperatures below 37 °C, commonly present with cutaneous manifestations initially, but are more rarely associated with ocular manifestations. To our knowledge, we report the first case of a patient presenting with sequential central retinal artery occlusion (CRAO) associated with cryoglobulinemia.

CASE PRESENTATION

A 69-year-old female with a history of indolent B-cell lymphoma associated cryoglobulinemia, treated hepatitis B infection and CRAO in the left eye presented with acute vision loss and diffuse retinal whitening with a cherry red spot in her right eye, suggestive of sequential CRAO. Laboratory studies revealed a cryocrit of 55% (normal  < 1%), elevated titres of cryoglobulin IgG at 1.98 g/L and cryoglobulin IgM at 3.78 g/L (normal  < 0.3 g/L)⁹, and elevated kappa free light chain at 283.5 mg/L (normal  < 0.06 g/L). Such elevated tires of cryoglobulins in the context of the patient's CRAO raised suspicion of cryoglobulinemia associated CRAO. The patient was promptly referred to rheumatology and oncology and was admitted for treatment including intravenous methylprednisone, rituximab and bendamustine chemotherapy.

CONCLUSIONS

We report a patient with a complex medical history presenting with significant vision loss due to a sequential CRAO likely associated with cryoglobulinemia. Although a direct relationship between cryoglobulinemia and CRAO cannot be confirmed in this case, it highlights the importance of considering cryoglobulinemia in high-risk patients with prior history of hematological malignancy or chronic hepatitis infection.

Serum cystatin C is an early renal dysfunction biomarker in patients with hepatitis C virus

Background

Hepatitis C virus (HCV) may induce extrahepatic manifestations as acute or chronic renal dysfunction. The aim was to evaluate the diagnostic role of some biomarkers as cystatin C, cryoglobulins, rheumatoid factor (RF), and complement C3 for extrahepatic renal affection in newly diagnosed patients with HCV infection.

Methods

Blood and urine were collected from randomized individuals screened for new HCV infection (n=400). The studied populations were divided into 3 groups: control group I: thirty healthy individuals not suffering from either liver or kidney diseases, group IIa: thirty HCV patients who have positive HCV antibody test but showed negative PCR test, and group IIb: thirty HCV patients who showed positive results for both HCV antibody and PCR tests.

Results

In HCV group IIb, levels of serum total bilirubin, AST and ALT, and urine albumin/creatinine ratio were increased whereas serum albumin and creatinine clearance were decreased versus other groups. However, the levels of blood urea nitrogen and serum creatinine were still within the normal range in all groups. In HCV group IIb, cystatin C, cryoglobulins, and RF levels were increased; meanwhile, serum creatinine/cystatin C ratio and complement 3 levels were decreased compared to the other groups. HCV-infected patients significantly had higher serum cystatin C (>1.24 mg/L, P<0.001) and lower creatinine/cystatin C ratio (<70.1μMol/mg, P=0.002), and cystatin C was significantly correlated with liver and kidney parameters.

Conclusion

High serum cystatin C and low creatinine/cystatin C ratio may be early indicators of mild renal dysfunction with normal serum levels of creatinine in HCV-infected individuals.

Antibodies: Friends, Foes, or Both? Lessons From COVID-19 for the Rheumatologist

ABSTRACT

Antibodies are a fundamental tool to fight infections but are intrinsically built as a double-edged sword. One side recognizes the microbial antigen, and the other gives a call to arms to fight infection by recruiting immune cells and triggering inflammation. A balanced immune response must combine a potent neutralizing antibody and a swift disposal of the invading agent by innate immune cells with the least tissue damage possible. The longer the immune system takes to control the infection, the higher the possibility for a self-sustaining inflammatory process with potentially fatal consequences for the host. In addition to quantity, the quality of antibodies also matters, because posttranslational modifications altering the N-glycan composition in Fc fractions may help tilt the balance to the effector side, by modifying their affinity for Fc receptors in immune cells. The COVID-19 pandemic has provided a wealth of data bolstering our understanding of the rules governing the production of protective and nonprotective antibodies. Also, it has broadened our understanding of the role of viruses in triggering autoimmunity and inflammation, and widened our knowledge of the different mechanisms that can be activated by viral infection and lead to autoantibody production, inflammation, and progressive tissue damage. In addition, the COVID-19 infection has contributed a great deal to our comprehension of the role of antibodies in the causation of cytokine storms and systemic inflammatory response syndrome, also seen in patients with systemic autoimmune diseases.

Practical Details for the Detection and Interpretation of Cryoglobulins

BACKGROUND

Cryoglobulins are immunoglobulins that precipitate at low temperature. Strict preanalytical and analytical conditions are critical for the detection of cryoglobulins.

CONTENT

This review will focus on practical recommendations for detection and characterization of cryoglobulins and the technical problems that may be encountered. A laboratory report format is proposed for presentation of these results that includes the parameters necessary for an optimal interpretation by clinicians. The first step of detection of cryoglobulins can be performed in any laboratory that has a 37 °C incubator and temperature-controlled centrifuge. The second step is the characterization of cryoglobulins, and this often must be performed in more specialized laboratories. Characterization includes immunoglobulin typing, for the classification of cryoglobulins and potential underlying disease(s); quantification of immunoglobulins and rheumatoid factor in the cryoprecipitate to define the pathogenicity; and quantification of serum complement, which is useful for diagnosis.

SUMMARY

These practical recommendations will be useful for the accurate detection of cryoglobulins, an essential step for the diagnosis of cryoglobulinemic vasculitis, a rare but severe clinical manifestation of cryoglobulins.

Cryoglobulinemic vasculitis: pathophysiological mechanisms and diagnosis

PURPOSE OF REVIEW

Cryoglobulins (CG) are immunoglobulins that precipitate in the cold, and dissolve at 37°C. In vivo, in cold exposed tissues and organs, they can induce vasculitis and occlusive vasculopathy after deposition on vascular endothelium under low temperature and high concentration conditions. Clinical manifestations are cutaneous (purpura, ulcers, vasomotor symptoms, and livedo reticularis), rheumatological (arthralgia and arthritis), and peripheral neuropathy (paresthesia and pain in the lower limbs). In profound organs such as the kidneys, CG deposition is less temperature-dependent, favored by local protein and anion concentrations, and can lead to glomerulonephritis. This review will focus on cryoglobulinemic vasculitis and vascular lesion, and their diagnosis.

RECENT FINDINGS

The mechanisms of vascular lesions of pathogenic CG in function of CG type and their characteristics are better defined. Optimal conditions for CG detection are critical. The importance of looking for underlying diseases, especially hepatitis C virus status in mixed CG, is reminded.

SUMMARY

A decision diagram for CG vasculitis diagnosis based on clinical and biological parameters is proposed.