Practical Details for the Detection and Interpretation of Cryoglobulins

Cryoglobulinemia concurrent with Leishmania infantum infection in a dog and its interference with two automated hematology analyzers

A 6-year-old, intact male English Bulldog presented for evaluation of weakness. Physical examination revealed mildly pale mucous membranes and ophthalmologic alterations. A complete blood cell count was performed on the Urit Smart V5 and the Sysmex XN-1000V, and showed several hematologic discrepancies between the analyzers. The Urit reported marked leukocytosis and thrombocytosis, and the Sysmex reported marked thrombocytosis on the impedance and optical RET channel but mild thrombocytopenia on the optical PLT-F channel. On the blood smear examination, there was an abundant proteinaceous material compatible with cryoglobulins. The red blood cell exhibited a notable degree of poikilocytosis. The number of leukocytes was found to be correlated with the Sysmex total white blood cell count, while the platelet count demonstrated a better correlation with the optical PLT-F channel from the Sysmex. Centrifugation of the blood in a capillary tube (at room temperature) identified a cryoglobulin precipitate. Additionally, the blood was reanalyzed soon after warming it to 37°C, which partially corrected most of the interferences. The serum protein electrophoresis demonstrated a marked hyperproteinemia with mild hypoalbuminemia and a marked hypergammaglobulinemia. On diagnostic imaging, a mild splenomegaly was noted. Cytology of the spleen showed Leishmania infantum infection, plasma cell hyperplasia, and extramedullary hematopoiesis. This is the first description of a dog infected with Leishmania. infantum with concurrent monoclonal hypergammaglobulinemia and cryoglobulinemia. We present a detailed description of the interference of cryoglobulin with the Urit Smart V5 and the Sysmex XN-1000V, along with the usefulness of Sysmex PLT-F in this condition.

Cryoglobulinemia Associated With Multiple Myeloma in a Dog Presenting With Epistaxis and Skin Lesions

A 10-year-old female neutered Labrador Retriever presented with epistaxis, discoloration and crusting of the nose and a necrotic lesion on the lip. Bloodwork revealed pancytopenia, azotemia, hypoalbuminemia and hyperglobulinemia. Aggregates of amorphous basophilic material were seen in a room-temperature blood smear which were not present in the sample after warming to 37°C, and grossly a cryoprecipitate was noted in the patient's serum at 4°C. This was interpreted as cryoglobulin. Computed tomography showed multiple heterogeneous lesions in the spleen. Cytology of the splenic lesions revealed marked plasma cell infiltration, consistent with neoplasia. Bone marrow aspiration revealed an increased proportion of plasma cells (approximately 38% of the total cells). Serum protein electrophoresis showed a monoclonal spike in the gamma globulin region. A diagnosis of multiple myeloma associated with cryoglobulinemia was made. The patient received palliative care with prednisolone while the owner was considering chemotherapy. However, she rapidly deteriorated and was euthanized. The combination of cryoglobulin precipitation and hyperviscosity syndrome was considered responsible for the patient's original symptoms. Cryoglobulinemia is an extremely rare phenomenon that is often associated with lymphoproliferative disorders. This report describes its association with multiple myeloma in a dog presenting with atypical initial signs.

Evaluation of cryoprotein investigation using a digital external quality assurance scheme

Background: Robust preanalytical and analytical processes are critical for the detection of cryoproteins. There is significant variation in practice in the detection, analysis and reporting. Results: A survey in 2018 of 137 laboratories participating in the UK National External Quality Assessment Service (UK NEQAS) (6) quality control program showed significant variation in the laboratory processes which highlighted the need for standardisation of the detection, analysis and reporting of cryoglobulins.Conclusion: The first available EQA scheme aiming to harmonise practice for cryoprotein testing has been developed by UK NEQAS and laboratories should participate in an appropriate EQA scheme to fulfil requirements for ISO accreditation.

Insights into the immunological description of cryoglobulins with regard to detection and characterization in Slovenian rheumatological patients

The detection of cryoglobulins (CG) used to diagnose cryoglobulinemic vasculitis requires strict adherence to protocol, with emphasis on the preanalytical part. Our main objectives were to introduce a more sensitive and specific protocol for the detection of CG and to characterize CG in Slovenian patients diagnosed with cryoglobulinemic vasculitis, other vasculitides, connective tissue diseases or non-rheumatic diseases examined at the Department of Rheumatology (University Medical Centre Ljubljana). Samples were routinely analyzed for the presence of CG with the protocol using the Folin-Ciocalteu reagent. In the newly introduced protocol, the type of CG was determined by immunofixation on visually observed positive samples and the concentration of CG in the cryoprecipitate and rheumatoid factor (RF) activity were measured by nephelometry. RF, C3c and C4 were measured in patients` serum and a decision tree analysis was performed using all results. The agreement between negative and positive results between the two protocols was 86%. Of the 258 patient samples tested, we found 56 patients (21.7%) with positive CG (37.5% - type II, 62.5% - type III). The RF activity was observed in 21.4% of CG positive subjects. The median concentration of type II CG was significantly higher than that of type III CG (67.4 mg/L vs. 45.0 mg/L, p = 0.037). Patients with type II had lower C4 concentrations and higher RF compared to patients with type III CG. In the decision tree, C4 was the strongest predictor of cryoglobulinemia in patients. With the newly implemented protocol, we were able to improve the detection and quantification of CG in the samples of our rheumatology patients and report the results to adequately support clinicians.

Screening for and diagnosis of monoclonal gammopathy

Monoclonal gammopathy is a spectrum of disorders characterised by clonal proliferation of plasma cells or lymphocytes, which produce abnormal immunoglobulin or its components (monoclonal proteins). Monoclonal gammopathies are often categorised as low-tumour-burden diseases (eg, amyloid light chain (AL) amyloidosis), premalignant disorders (such as monoclonal gammopathy of undetermined significance and smouldering multiple myeloma), and malignancies (eg, multiple myeloma and Waldenström's macroglobulinaemia). Such diversity of concentration and structure makes monoclonal protein a challenging clonal marker. This article provides an overview on initial laboratory testing of monoclonal gammopathy to guide clinicians and laboratory professionals in the selection and interpretation of appropriate investigations.

Recent updates in the diagnosis and management of cryoglobulinemic vasculitis

INTRODUCTION

Cryoglobulinemic vasculitis (CV), also known as mixed cryoglobulinemic syndrome (MCS), is a systemic vasculitis that affects small blood vessels. It exhibits a wide range of clinical manifestations, making its treatment a continuing challenge for physicians.

AREAS COVERED

We conducted a comprehensive review to evaluate the current status of diagnosis, management, and treatment of mixed cryoglobulinemia (MC). The accurate clinical and serological evaluation plays a vital role in diagnosing MC, identifying potential comorbidities, and monitoring its main manifestations and complications. Treatment strategies should be individualized based on the underlying etiopathogenesis, the severity of organ involvement, and the associated underlying disease. At present, the two mainstays of CV treatment are direct antiviral agents (for HCV-related CV) and B-cell-targeted therapy.

EXPERT OPINION

MC remains one of the few autoimmune diseases where the etiology is known, at least for the majority of patients. Its pathogenetic mechanism offers a unique opportunity to investigate the interplay between infections and the immune system. Moving forward, the primary challenge will continue to lie in the treatment of resistant or refractory cases of CV, particularly those associated with autoimmune diseases, or cases classified as 'essential' CV.

Cryoglobulinemia in systemic lupus erythematosus: a retrospective study of 213 patients

Objectives

The clinical value of cryoglobulinemia (CG) in systemic lupus erythematosus (SLE) is largely unknown. The aim of this retrospective study was to describe the characteristics of CG in SLE, its impact on SLE phenotype, and the features associated with cryoglobulinemic vasculitis (CryoVas) in SLE patients.

Methods

This retrospective study conducted in a French university hospital reviewed the data from 213 SLE patients having been screened for CG between January 2013 and December 2017. SLE patients positive for CG were compared to SLE patients without CG. Patients were classified as CryoVas using the criteria of De Vita et al.

Results

Of the 213 SLE patients included (mean age 29.2 years, female sex 85%), 142 (66%) had at least one positive CG in their history, 67% of them having a persistent CG at follow-up. CG was type III in 114 (80%) cases and type II in 27 (19%) cases. The mean concentration of the cryoprecipitate was 40mg/L (range 0-228). Patients with CG had significantly more C4 consumption. Among patients with CG, 21 (15%) developed a CryoVas. The clinical manifestations of patients with CryoVas were mainly cutaneous (purpura, ulcers, digital ischemia) and articular, without any death at follow-up. Severe manifestations of CG included glomerulonephritis in 1/21 (5%) patients and central nervous system involvement in 4/21 (19%) patients. A response to first-line treatments was observed in 12/13 (92%) patients, but relapses were observed for 3 of them.

Conclusion

CG is frequent in SLE, but mostly asymptomatic. CryoVas features involve mostly joints, skin, and general symptoms. CryoVas in SLE appears to be a specific condition, with a low prevalence of neuropathy, membranoproliferative glomerulonephritis, and severe manifestations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02857-z.

• Cryoglobulinemia is frequent in SLE, but mostly asymptomatic.

• Sixty-six percent of SLE patients tested positive for cryoglobulins, and 15% of the SLE patients with cryoglobulinemia developed a cryoglobulinemic vasculitis.

• Features of the cryoglobulinemic vasculitis mainly involved skin, joints, and general signs. Severe manifestations of vasculitis were rare.