SARS-CoV-2 infection is not associated with the emergence of monoclonal gammopathies

BACKGROUND

Upon infection activated plasma cells produce large quantities of antibodies which can lead to the emergence of a monoclonal component (MC), detectable by serum protein electrophoresis (SPEP). This study aims to investigate any correlation between SARS-CoV-2 infection and MC development and, if identified, whether it persists during follow-up.

METHODS

SPEPs of 786 patients admitted to hospitals between March 01 2020 and March 31 2022 were evaluated. Positive (SARS-CoV-2+) and negative (SARS-CoV-2-) patients to nasopharyngeal swab for SARS-CoV-2 by RT-PCR were included. The persistence/new occurrence of MC was investigated for all patients during follow-up. Patient groups were compared by chi-square analysis.

RESULTS

MC was identified in 12% of all patients admitted to hospital, of which 28.7% were SARS-CoV-2+. The most common immunoglobulin isotype in both groups was IgG-k. There was no correlation between MC development and SARS-CoV-2 infection (p = 0.173). Furthermore, the risk of MC persistence in SARS-CoV-2-negative patients was revealed to be higher than in the SARS-CoV-2+ at follow-up (HR = 0.591, p = 0.05).

CONCLUSIONS

Our study suggests that the detection of MC during SARS-CoV-2 infection is most likely due to the hyperstimulation of the humoral immune system, as also occurs in other viral infections.

A new challenge for urinary free light chains: assessment of the upper reference limit in healthy subjects

OBJECTIVE

Free light chains (FLCs) can be measured in both urine (uFLC) and serum (sFLC) in immunochemistry. We aim to compare FLC levels in serum and urine assessed among healthy volunteers and measured upper reference limits (URLs) of urinary FLC to creatinine ratio (uFLC/uCr) in mg/g to compare with the manufacturer's recommended URLs.

PATIENTS AND METHODS

Eligibility criteria: normal serum and urine FLC measure and negative serum/urinary immunofixation. Immunoturbidimetry was used to assess both κ and λ FLCs. The URLs were calculated with the 97.5th percentile of uFLC concentrations according to the Clinical and Laboratory Standards Institute recommendations.

RESULTS

126 healthy subjects (median age 46 years, 62% females) met the inclusion criteria. Median concentrations of κ and λ sFLCs were similar both for males and females without significant differences. κ and λ uFLCs were significantly higher in males than in females (p < 0.001 and p = 0.004, respectively). Slower clearance for λ FLC compared to κ FLC was observed with an increased κ/λ uFLC ratio in both males and females. URLs for male and female subjects: κ uFLC mg/g uCr = 34.35 vs. 23.18, and λ uFLC mg/g uCr = 3.59 vs. 1.96, respectively compared well with manufacturer's URLs.

CONCLUSIONS

FLC catabolism is gender-dependent and occurs less rapidly in λ FLC than in κ FLC. The determination of the URL of uFLC, as uFLC/uCr, in healthy subjects in morning urine, proved to be consistent with the manufacturer's recommendations, but with a significant difference according to gender.

Prognostic Relevance of Multi-Antigenic Myeloma-Specific T-Cell Assay in Patients with Monoclonal Gammopathies

Multiple Myeloma (MM) typically originates from underlying precursor conditions, known as Monoclonal Gammopathy of Undetermined Significance (MGUS) and Smoldering Multiple Myeloma (SMM). Validated risk factors, related to the main features of the clonal plasma cells, are employed in the current prognostic models to assess long-term probabilities of progression to MM. In addition, new prognostic immunologic parameters, measuring protective MM-specific T-cell responses, could help to identify patients with shorter time-to-progression. In this report, we described a novel Multi-antigenic Myeloma-specific (MaMs) T-cell assay, based on ELISpot technology, providing simultaneous evaluation of T-cell responses towards ten different MM-associated antigens. When performed during long-term follow-up (mean 28 months) of 33 patients with either MGUS or SMM, such deca-antigenic myeloma-specific immunoassay allowed to significantly distinguish between stable vs. progressive disease (p < 0.001), independently from the Mayo Clinic risk category. Here, we report the first clinical experience showing that a wide (multi-antigen), standardized (irrespective to patients' HLA), MM-specific T-cell assay may routinely be applied, as a promising prognostic tool, during the follow-up of MGUS/SMM patients. Larger studies are needed to improve the antigenic panel and further explore the prognostic value of MaMs test in the risk assessment of patients with monoclonal gammopathies.

Analysis of cryoproteins with a focus on cryofibrinogen: a study on 103 patients

OBJECTIVES

Cryofibrinogen (CF) is an abnormal protein in plasma that precipitates at 4 °C and dissolves at 37 °C. Whilst serum cryoglobulins (CGs) analysis is common practice, CF investigation is rarely performed. This study aims to describe the testing methodology developed at our laboratory, potential pitfalls for all analytical phases, the distribution among hospital wards and clinical conditions underlying test requests and clinical conditions in which to order CF analysis is useful.

METHODS

Retrospective analysis of laboratory samples received between January 2019 and June 2021 with CF testing requests.

RESULTS

A complete protocol for CF pre-analytical, analytical and post-analytical phases are supplied. Most test requests were received from the rheumatology department for systemic sclerosis or liver transplant screening. Among the 103 in-patients included, CF+ was confirmed in 68 patients (66%). Of observed CF+ patients (n=68) most cases were CGs- (n=44, 67%). Isolated CF was found in 43% of the cases. Among CF- patients (n=35; 34%) only 2 patients had positive CGs (CGs+). Among rheumatology patients (n=66), isolated CF+ was observed in 45% (n=30/66), whilst among patients with systemic sclerosis with CF+ (n=19), isolated CF+ was detected in 79% (n=15/19).

CONCLUSIONS

Described analytical procedures may be used for the creation of harmonized recommendations and indications for CF analysis. Isolated CF positivity among hospitalized patients, predominantly rheumatology and systemic sclerosis patients, appears higher than rates previously reported in literature. We propose CF test recommendations should be included in investigation protocols for diseases where cryofibrinogenemia may occur.

The dark side of current analytic methods for Bence Jones Proteinuria

OBJECTIVE

Bence Jones proteinuria (BJP) refers to monoclonal free immunoglobulin light chains detected in urine, deriving from the clonal expansion of plasma cells in the bone marrow in patients with plasma cell dyscrasias, associated with monoclonal gammopathies of uncertain origin. This review summarizes routinely diagnostic procedures to assess BJP highlighting critical steps of pre-analytical, analytical, and post-analytical phases.

QUALITATIVE AND QUANTITATIVE METHODS

The best option for BJP detection is the first morning void urine sample and immunofixation electrophoresis detection technique (IFE) the recommended method, with the employment of specific polyvalent antisera. Other qualitative tests for a quick evaluation of BJP are currently available. Densitometric analysis performed on the 24-hour urine is the recommended method to quantify BJP. To overcome the 24-hour collection, it is possible to use morning urine sample and correlate the assessed value of BJP to creatininuria. In addition to the traditional ones, we here reviewed screening methods currently used to avoid false negatives and reduce the time around test (TAT), together with immunochemical quantification methods for increased sensitivity, after checking BJP by IFE. Mass spectrometry emerges as a new challenge in the determination of BJP.

CONCLUSIONS

The employment of different based-assays methods may be useful for diagnostic purposes to improve the accuracy of BJP monitoring in monoclonal gammopathies.

POS0896 CRYOFIBRINOGEN-ASSOCIATED SYSTEMIC SCLEROSIS: POSSIBLE CORRELATIONS WITH SCLERODERMA DIGITAL ULCERS AND PULMONARY ARTERIAL HYPERTENSION

Background

Cryofibrinogenemia (CF) is a rare disorder characterized by the presence of an abnormal protein in the plasma that precipitates when cooled and redissolves at room temperature (1). CF is rarely symptomatic, therefore it is often underestimated. Nevertheless, the cryoprecipitation of native fibrinogen could induce thrombotic occlusion of small and medium sized vessels; as a consequence, this condition could become potentially lethal without the proper treatments. CF is classified into an essential and secondary form. The association of CF with Systemic Sclerosis (SSc) is described in literature (2-4); however, the role of this phenomenon it is not completely clarified, especially because some clinical aspects could be similar in both conditions.

Objectives

The aim of our study was to analyze the clinical, laboratory, instrumental and therapeutic features of SSc patients with cryofibrinogenemia, with particular attention to the possible prevention strategy and appropriate therapy of SSc digital ulcers.

Methods

101 SSc patients (M:F 1:13) referring to the SSc Unit-Rheumatology Unit of our University Hospital have been tested both for cryofibrinogen and cryoglobulins from February 2020 to January 2022. Clinical, laboratory, instrumental features and ongoing therapies were collected.

Results

Patients with diffuse cutaneous form, limited cutaneous form, and sine-scleroderma subsets were 20 (19,8%), 79 (78,2%), and 2 (2,0%), respectively. The overall positivity for CF was 69,3%, of which 90,7% as isolated CF and 9,3% in addition to cryoglobulins. No correlation between CF positivity and positivity for rheumatoid factor, Scl-70, CENP B, anti-fibrillarin, anti-U1RNP, anti-Th/To, anti-Ku, anti-MDA5, anti-mitochondrial, anti-SSA, anti-SSB, anti-citrullinated peptide, anti-phospholipids, anti-CORE, and anti-HCV antibodies was observed. An inverse correlation trend between CF positivity and anti-RNAP3 antibodies positivity (OR=0.0577, 95% CI 0.0029-1.1537, p=0.0620) was noted. No significant correlation between CF positivity and interstitial lung disease, pulmonary arterial hypertension (PAH), history of digital ulcers, and amputation was recorded; however, considering cryocrit sample ≥1%, a correlation between the presence of an estimated pulmonary arterial systolic pressure (ePASP) higher than 30 mmHg and the positivity of CF was obtained (OR = 2.71, 95% CI 1.01-7.28, p=0.0482). The same association was achieved if we considered patients without endothelin receptor antagonist therapy (n=47) and CF positivity (OR=6.19, 95% CI 1.19-32.2, p=0.0304). Furthermore, no correlation between CF positivity and the presence of digital ulcers at the moment of the blood sampling was verified; however, if we stratified patients according to their ongoing treatments (absence of an endothelin receptor antagonists therapy plus PDE5 inhibitors), a significant correlation between digital ulcers and CF positivity emerged (OR=8.14, 95% CI 1.03-64,5, p=0.0470, n=91).

Conclusion

Our preliminary results on this issue are extremely interesting as they can open new perspectives on the identification of cryofibrinogen as possible prognostic marker that could be involved in the pathogenesis of scleroderma digital ulcers and PAH. Moreover, therapies which are currently used for the treatment of PAH and the management of digital ulcers, could determine circulating cryofibrinogen disappearance, with possible challenging future impact on SSc therapeutic approaches.

References

[1]Michaud M, Pourrat J. Cryofibrinogenemia. J Clin Rheumatol Pract Rep Rheum Musculoskelet Dis. aprile 2013;19(3):142–8.

[2]Kao L, Weyand C. Vasculitis in Systemic Sclerosis. Int J Rheumatol. 30 settembre 2010;2010:e385938.

[3]Kocoloski A et al, Successful management of secondary cryofibrinogenaemia using bosentan therapy. Rheumatol Oxf Engl. 1 ottobre 2018;57(10):1868–70.

[4]Barrett MC et al, Cryofibrinogenaemia and acute gangrene in systemic sclerosis. Postgrad Med J. ottobre 1986;62(732):935–6.

Disclosure of Interests

None declared

AB0525 NATURAL HISTORY OF CRYOGLOBULINEMIA FROM 2000 TO 2018 FROM THE LABORATORY POINT OF VIEW: AN ANALYSIS OF CRYOGLOBULIN CHARACTERISTICS IN A SINGLE CENTER

Background:

Big data refers to large amounts of information. With today’s ever-improving technologies created by the automation and digitization, it becomes easier to convert data into relevant information, which can be used to provide better patient management, especially when it occurs a rare condition such as cryoglobulinemia (CRG).

CRG is due to an immunoglobulins (Ig) that precipitate at low temperatures. There are 3 types of CRG: type I: monoclonal Ig; type II: monoclonal Ig + polyclonal Ig; type III: 2 polyclonal Ig.

Objectives:

The aim of this study was to analyse the available data coming to the Department of Laboratory Medicine of Modena to describe the population of patients suffering of CRG.

Methods:

Data from the Modena Labs network were extracted by means of the software “Pagoda”, for statistical purposes, directly connected to the Laboratories Information System (LIS). Considered time period 2000-2018

Results:

The analysed samples were 28,847, 4901 (17%) of which positive to the cryoglobulins (CR) detection. The typing positive CR were 4190 (85%): type 1 7.8 %, type II 48.54% and type III 43.8% The positive samples belonged to 2528 patients. Patients were 1563 (62%) women, average age 66±16, and 965 (38%) men, average age 62±16. (female/male ratio = 1.62) No statistically significant difference regarding sex and age between the 3 types. The cryoglobulinemia phenomenon is quite complex and the typing of monoclonal, polyclonal components of the Ig classes and chains has made it possible to identify 41 possible combinationsOut of 115 patients with Type 1 cryoglobulin, 73% had a monoclonal IgM and 36% monoclonal IgG; 11.2% both monoclonal IgG and IgM. The к light chain was the most frequent: 55,6% IgM-k and 23,4% IgG-k vs 29% IgM-λ and 18.2% IgG-λ. Two patients had an IgA-k cryoglobulin.

Patients with Type 2 cryo were 781: monoclonal IgM-k 587 (75.1 %), 126 IgM-λ (16.1 %), 52 IgG-k (6.6 %), IgG-λ (5%), 1 IgA-λ; 2.8% had both IgG and IgM. Out of 1204 patients with Type 3 cryo, 74.8% had both polyclonal IgG and IgM, 13,8% had isolated IgM or IgG (9%); 4.8 % IgG-IgA-IgM together, both IgG and IgA in only 0,5% of patients. Almost the 50% (1255) of the patients had a diagnosis supporting the request of CR:

HCV, 604 (48%); chronic hepatitis, 177 (14%); rheumatologic disorder, 107 (9%); autoimmune diseases, 83 (7%), nephropathy, 80 (7%); others, 204 (15%).

Genotyped HCV+ patients were 290 (48%), with the following results: 1b, 136 (47%); 2a/2c, 65 (22%); 3a, 26 (9%); others 63 (22%).

Conclusion:

The data show that CRG is a pathology which affects the elderly and especially women, as in autoimmune and rheumatological diseases. The predominant CRG type is the III and the most frequently related pathology to the request for CR is HCV+ and chronic hepatitis. The most common HCV genotype are 1b and 2a/2c The cryoglobulinemia phenomenon is complex and laboratory typing is intriguing.

Starting from this preliminary descriptive study, it will be possible, with the available data, to perform elaborations that allow to relate CRG with the diagnosis and verify the effect of therapy.

Big Data methods’ application represents an undeniable resource for public institutions when carrying out strategic decision-making processes.

Disclosure of Interests:

None declared