Cryoglobulins: Identification, classification, and novel biomarkers of mysterious proteins

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.

Thymic stromal lymphopoietin signaling in B cells from progenitors to plasma cells

Thymic stromal lymphopoietin is an established pleotropic alarmin cytokine that is generated at barrier tissues to induce type 2 immune responses, but its role in regulating the diversity of B cells is poorly understood. Here, we will highlight the key findings that underpin our limited understanding of the role thymic stromal lymphopoietin in modulating different stages of B cell development. We will also provide an overview of how thymic stromal lymphopoietin drives B cell-mediated immune disease and how novel thymic stromal lymphopoietin-blocking biologics could be used to modulate B cell responses. Thymic stromal lymphopoietin is critical for the regulation, diversity, and longevity of humoral immunity.

Acute Kidney Injury in Autoimmune-Mediated Rheumatic Diseases

Acute kidney injury (AKI) is increasingly affecting hospitalized patients worldwide. Patients with inflammatory rheumatic diseases, although primarily impacted by functional impairment and sometimes structural damage to joints, bones, and muscle tissue, may also develop AKI during the course of their disease. This narrative review aimed to summarize potential causes of AKI and the associated disease patterns. The following databases were searched for references: PubMed, Web of Science, Cochrane Library, and Scopus. The search period covered from 1958 to 2024. Certain inflammatory rheumatic diseases increase the risk of AKI due to specific types of kidney disease. However, the most common conditions, such as rheumatoid arthritis and spondylarthritis, rarely cause AKI directly. Among the medications used for pain and sometimes disease activity control, nonsteroidal anti-inflammatory drugs (NSAIDs) can potentially induce AKI, even progressing to acute tubular necrosis. There is evidence that certain rheumatic diseases are associated with increased risk of AKI, independently of directly affecting kidney function or structure. However, the data on this topic are quite limited. AKI is a potentially significant issue for patients with inflammatory rheumatic diseases. Additional data on the increased risk of AKI, independent of direct kidney involvement, are needed.

Identification of Key Predictors of Cryoglobulinemia Severity at Diagnosis: Threshold, Type, and Severity Score at Diagnosis

Background: Cryoglobulinemia (CG) syndrome is a heterogeneous condition characterized by the presence of cryoglobulins in serum, often leading to vasculitis with protean clinical manifestations. Understanding the presentation of cryoglobulinemia-related symptoms based on cryoprecipitate levels, GC type, and severity at diagnosis is essential for effective management. Hence, this study aimed to provide a comprehensive analysis of patients with positive cryoglobulin detection to investigate these aspects. Methods: We conducted a retrospective review of clinical charts from patients with positive cryoglobulin detection at Colmar Hospital between May 2015 and April 2019. Results: Among 166 patients with positive cryoglobulins, the median cryoprecipitate value was 37 mg/L [IQR: 25-70], with 62% of patients below the 50 mg/L threshold. High cryoprecipitate levels were associated with C-virus hepatitis (p = 0.0007), increased fatigue (p = 0.001), fever (p = 0.0013), weight loss (p = 0.028), and musculoskeletal symptoms (p = 0.002). These patients also exhibited decreases in complement fractions (p-values 0.017 to 0.006). At the end of the one-year follow-up, they required frequent renal replacement therapy (p < 0.0001) and had a higher mortality rate (p = 0.02). Based on the CG type, patients with type I GC had splenomegaly (p = 0.039) and hemopathy (p = 0.001). According to severity at initial presentation, the severe patients had more purpura (p < 0.001), Raynaud's phenomenon (p = 0.039), and leukocytoclastic vasculitis on skin biopsy (p < 0.001), along with higher cryoprecipitate levels (p = 0.011). Multivariate analysis identified purpura (OR: 10.25), hematological malignancy (OR: 7.06), Raynaud's phenomenon (OR: 6.41), and cryoprecipitate levels (OR: 1.02) as significant markers of disease severity serving for the development of a severity score for clinical practice. Conclusions: This study identifies severity markers in patients with positive cryoprecipitate and proposes a score related to severity at diagnosis.

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.

Clinical and Serological Profiles in Cryoglobulinemia: Analysis of Isotypes and Etiologies

Objectives: Cryoglobulinemia (CG) is marked by abnormal immunoglobulins (Ig) in serum, precipitating at temperatures below 37 °C. Current classification categorizes CG into three subtypes (types I, II, and III) based on Ig clonality. The features distinguishing patients with CG based on their etiology remain unidentified. Aiming to characterize clinical and serological profiles of CG individuals, we conducted an observational analysis of a large cohort of patients and compared their characteristics based on underlying causes: hepatovirus (HV) infections, rheumatic diseases (RD), hematological disorders, and unidentified etiology (essential CG). Methods: We analyzed 252 cryoglobulin-positive serum samples from 182 patients and classified these into the four etiological groups. A separate sub-analysis was carried out for 10 patients meeting criteria for multiple diseases. We collected demographic, clinical, and laboratory data: CG characterization, complement (C3 and C4) levels, antinuclear antibodies (ANA), and rheumatoid factor (RF). Kruskal-Wallis and Wilcoxon-Mann-Whitney U-tests were used for comparisons. Results: Most patients (93.3%) had mixed cryoglobulinemia (types II + III), with 6.7% having type I. HV infection, predominantly hepatitis C, was the main (52.9%) associated condition within the cohort, followed by rheumatic (27.3%) and hematological (9.8%) disorders. In our cohort, ANA were frequent (45.3%) and often associated with RF positivity (43.6%) and decreased complement levels (C3: 42.4%, C4: 32.5%). Essential CG and CG associated with RD had a higher prevalence of cutaneous manifestations (p < 0.01) and renal involvement (p = 0.017). Hematological disorder-related CG showed higher cryoglobulin and RF concentrations (p < 0.01), despite milder symptoms. Conclusions: Our study underscores a mixed prevalence of CG across disease subgroups, with hepatitis-C virus as the primary factor, followed by rheumatic and hematological disorders. Four clinical and serological profiles of CG were identified based on their etiologies.

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.

Unveiling Mixed Cryoglobulinemia in Suspected Sepsis Without a Source

Cryoglobulinemia is an uncommon condition characterized by the presence of cryoprecipitable immune complexes in circulation, leading to clinical symptoms like purpura, muscle weakness, and joint pain. Specifically, mixed cryoglobulinemia involves the formation of these complexes due to rheumatoid factors, mainly IgM, occasionally IgG or IgA. Previously, Hepatitis C (HCV) was a common cause of mixed cryoglobulinemia, as the chronic HCV infection triggered immune responses that resulted in cryoglobulin formation. However, the emergence of direct-acting antivirals (DAAs) for HCV treatment has shifted the landscape, with autoimmune and lymphoproliferative disorders becoming more prominent etiological factors for mixed cryoglobulinemia. This case report features a 67-year-old woman with a history of Hepatitis C-related cirrhosis. She presented at the emergency department with signs of septic shock and widespread joint pain, particularly in the knees, shoulders, and neck. Effective sepsis management was achieved using antibiotics, albumin infusion, and midodrine. Nonetheless, significant cervical and bilateral knee pain persisted. Further examination uncovered hypocomplementemia and positive results for rheumatoid factors (IgA, IgM, IgG) and cryoglobulin agglutination, confirming the diagnosis of mixed cryoglobulinemia. This case emphasizes the importance of considering mixed cryoglobulinemia in chronic Hepatitis C patients displaying fatigue and joint pain, even in the absence of the traditional clinical manifestations. Moreover, the case underscores the dual benefits of DAA treatment for Hepatitis C in individuals with mixed cryoglobulinemia by achieving viral eradication and alleviating cryoglobulinemia-related symptoms, thus preventing further organ damage.

Monoclonal Gammopathy of Undetermined Cardiovascular Significance; Current Evidence and Novel Insights

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant condition characterized by the presence of low levels of a monoclonal protein in the serum and a low percentage of clonal plasma cells in the bone marrow. MGUS may progress to multiple myeloma or other plasma cell disorders at a rate of 1% annually. However, MGUS may also have adverse effects on the cardiovascular system independent of its malignant potential. Emerging data have shown that MGUS is associated with cardiovascular disease. The mechanisms underlying this association are not fully understood but may involve genetic abnormalities, vascular calcification, cryoglobulinemia, cold agglutinin disease, autoantibodies and the direct or indirect effects of the monoclonal protein on the vascular endothelium. Herein, we review current evidence in this field and we suggest that patients with MGUS may benefit from regular cardiovascular risk assessment to prevent severe cardiovascular complications, in parallel with close hematological follow-up to monitor potential disease progression.

Cryoglobulinemia Leading to the Diagnosis of Low Grade Serous Ovarian Carcinoma

We present the case of a 64-year-old female who was referred by her oncologist to benign hematology clinic for persistent asymptomatic cryoglobulinemia. Workup led to diagnosis of a rare low grade ovarian serous carcinoma. We briefly review the pathophysiology and clinical significance of cryoglobulinemia and the diagnosis and management of low grade serous ovarian carcinoma.

Therapeutic Potential of Rituximab in Managing Hepatitis C-Associated Cryoglobulinemic Vasculitis: A Systematic Review

(1) Background. Hepatitis C infection often leads to extrahepatic manifestations, including cryoglobulinemic vasculitis. This systematic review aimed to assess the efficacy and safety of rituximab in treating hepatitis C-associated cryoglobulinemic vasculitis. (2) Methods. Following PRISMA guidelines, databases were searched for relevant studies. Eligibility criteria included studies on hepatitis C-associated cryoglobulinemic vasculitis treated with rituximab. (3) Results. Nine studies met the eligibility criteria and were included in this analysis. Rituximab was commonly administered at 375 mg/m2 weekly for one month. The results consistently demonstrated the efficacy of rituximab, whether as a standalone treatment or as part of a therapeutic regimen. The combination of rituximab with Peg-IFN-α and ribavirin significantly increased the complete response rate compared to Peg-IFN-α and ribavirin alone (54.5% vs. 33.3%, p < 0.05). The 3-year sustained response rate was notably higher in the rituximab combination group (83.3% vs. 40%). In another trial, rituximab achieved remission in 83.3% of patients at 6 months, compared to only 8.3% in the control group. The efficacy of rituximab was supported by long-term experience, with clinical benefits in patients with severe cryoglobulinemic vasculitis, including those resistant to standard therapies. Mild adverse events were generally reported, with rare severe reactions in some studies. (4) Conclusions: In conclusion, rituximab appeared to be effective and safe in managing hepatitis C-associated cryoglobulinemic vasculitis, either alone or with antiviral therapy.

Serological and Molecular Characterization of Hepatitis C Virus-Related Cryoglobulinemic Vasculitis in Patients without Cryoprecipitate

Prolonged B cells stimulation due to the Hepatitis C virus (HCV) can result in autoimmunity, stigmatized by rising levels of cryoglobulins (CGs), the rheumatoid factor (RF), and free light chains (FLC) of immunoglobulins (Ig) associated with a range of symptoms, from their absence to severe cryoglobulinemic vasculitis and lymphoma. Here, we aimed to identify an immunological signature for the earliest stages of vasculitis when cryoprecipitate is still not detectable. We firstly analyzed the IgG subclasses, FLC, and RF in 120 HCV-RNA-positive patients divided into four groups according to the type of cryoprecipitate and symptoms: 30 asymptomatic without cryoprecipitate (No Cryo), 30 with vasculitis symptoms but without CGs that we supposed were circulating but still not detectable (Circulating), 30 type II and 30 type III mixed cryoglobulinemia (Cryo II and Cryo III, respectively). Our results revealed that patients with supposed circulating CGs displayed a pattern of serological parameters that closely resembled Cryo II and Cryo III, with a stronger similarity to Cryo II. Accordingly, we analyzed the groups of Circulating and Cryo II for their immunoglobulin heavy chain (IgH) and T-cell receptor (TCR) gene rearrangements, finding a similar mixed distribution of monoclonal, oligoclonal, and polyclonal responses compared to a control group of ten HCV-RNA-negative patients recovered from infection, who displayed a 100% polyclonal response. Our results strengthened the hypothesis that circulating CGs are the origin of symptoms in HCV-RNA-positive patients without cryoprecipitate and demonstrated that an analysis of clonal IGH and TCR rearrangements is the best option for the early diagnosis of extrahepatic complications.

Collection and processing of hematopoietic progenitor cell products at risk of presenting with cold agglutination

BACKGROUND AIMS

Cold agglutinins are commonly identified in transfusion laboratories and are defined by their ability to agglutinate erythrocytes at 3-4°C, with most demonstrating a titer >64. Similarly, cryoglobulins can precipitate from plasma when temperatures drop below central body temperature, resulting in erythrocyte agglutination. Thankfully, disease associated from these autoantibodies is rare, but unfortunately, such temperature ranges are routinely encountered outside of the body's circulation, as in an extracorporeal circuit during hematopoietic progenitor cell (HPC) collection or human cell therapy laboratory processing. When agglutination occurs ex vivo, complications with the collection and product may be encountered, resulting in adverse events or product loss. Here, we endeavor to share our experience in preventing and responding to known cases at risk of or spontaneous HPC agglutination in our human cell therapy laboratory.

CASE REPORTS

Four cases of HPC products at risk for, or spontaneously, agglutinating were seen at our institution from 2018 to 2020. Planned modifications occurred, including ambient room temperature increases, tandem draw and return blood warmers, warm product transport and extended post-thaw warming occurred. In addition, unplanned modifications were undertaken, including warm HPC product processing and plasma replacement of the product when spontaneous agglutination of the product was identified. All recipients successfully engrafted after infusion.

CONCLUSIONS

While uncommon, cold agglutination of HPC products can disrupt standard processes of collection and processing. Protocol modifications can circumvent adverse events for the donor and minimize product loss. Such process modifications should be considered in individuals with known risks for agglutination going to HPC donation/collection.

Monoclonal Gammopathy of Thrombotic Significance

The current review provides an overview of the thrombotic risk observed in patients with MG who do not otherwise require treatment. We discuss clinical and biomarker studies that highlight the heterogenous hemostatic profile observed in these patients and how knowledge has evolved over the past 20 years. Biomarker studies suggest shared biologic features between multiple myeloma and monoclonal gammopathy of undetermined significance (MGUS), which involves both hypercoagulability and platelet activation. Hemostatic abnormalities identified in MGUS patients cannot be translated into clinical practice as they lack correlation to clinical events. The prothrombotic phenotype of MGUS patients has not been ascertained yet, but novel data on coagulation markers are promising. We also review rare conditions associated with the thrombogenic properties of the monoclonal protein that predispose to arterial, venous or microthrombotic events and demonstrate that the M-protein can be linked to clinically significant thrombotic events. Cryoglobulinemia, cryofibrinogenemia, cryo-crystaloglobulinemia and MG-related antiphospholipid syndrome are reviewed. We propose the new umbrella term "monoclonal gammopathy of thrombotic significance" (MGTS) to refer to significant, recurrent thrombotic events in patients with MGUS that provide a rationale for targeting the underlying plasma cell clone. Identifying MGUS patients at high risk for thrombotic events is currently a challenge.

Autoimmune Rheumatic Diseases and Vascular Function: The Concept of Autoimmune Atherosclerosis

Autoimmune rheumatic diseases (AIRDs) with unknown etiology are increasing in incidence and prevalence. Up to 5% of the population is affected. AIRDs include rheumatoid arthritis, system lupus erythematosus, systemic sclerosis, and Sjögren's syndrome. In patients with autoimmune diseases, the immune system attacks structures of its own body, leading to widespread tissue and organ damage, which, in turn, is associated with increased morbidity and mortality. One third of the mortality associated with autoimmune diseases is due to cardiovascular diseases. Atherosclerosis is considered the main underlying cause of cardiovascular diseases. Currently, because of finding macrophages and lymphocytes at the atheroma, atherosclerosis is considered a chronic immune-inflammatory disease. In active inflammation, the liberation of inflammatory mediators such as tumor necrotic factor alpha (TNFa), interleukine-6 (IL-6), IL-1 and other factors like T and B cells, play a major role in the atheroma formation. In addition, antioxidized, low-density lipoprotein (LDL) antibodies, antinuclear antibodies (ANA), and rheumatoid factor (RF) are higher in the atherosclerotic patients. Traditional risk factors like gender, age, hypercholesterolemia, smoking, diabetes mellitus, and hypertension, however, do not alone explain the risk of atherosclerosis present in autoimmune diseases. This review examines the role of chronic inflammation in the etiology-and progression-of atherosclerosis in autoimmune rheumatic diseases. In addition, discussed here in detail are the possible effects of autoimmune rheumatic diseases that can affect vascular function. We present here the current findings from studies that assessed vascular function changes using state-of-the-art techniques and innovative endothelial function biomarkers.