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In individuals who have once developed humoral immunity to an infectious/foreign antigen, the antibodies present in their body can mediate instant protection when the antigen re-enters. Such antigen-specific antibodies can be readily detected in the serum. Long term humoral immunity is, however, also critically dependent on the ability of memory B cells to engage in a secondary antibody response upon re-exposure to the antigen. Antibody molecules in the body are short lived, having a half-life of weeks, while memory B cells have a life span of decades. Therefore, the presence of serum antibodies is not always a reliable indicator of B cell memory and comprehensive monitoring of humoral immunity requires that both serum antibodies and memory B cells be assessed. The prevailing view is that resting memory B cells and B cell blasts in peripheral blood mononuclear cells (PBMC) cannot be cryopreserved without losing their antibody secreting function, and regulated high throughput immune monitoring of B cell immunity is therefore confined to—and largely limited by—the need to test freshly isolated PBMC. Using optimized protocols for freezing and thawing of PBMC, and four color ImmunoSpot® analysis for the simultaneous detection of all immunoglobulin classes/subclasses we show here that both resting memory B cells and B cell blasts retain their ability to secrete antibody after thawing, and thus demonstrate the feasibility of B cell immune monitoring using cryopreserved PBMC.

In individuals who have once developed humoral immunity to an infectious/foreign antigen, the antibodies present in their body can mediate instant protection when the antigen re-enters. Such antigen-specific antibodies can be readily detected in the serum. Long term humoral immunity is, however, also critically dependent on the ability of memory B cells to engage in a secondary antibody response upon re-exposure to the antigen. Antibody molecules in the body are short lived, having a half-life of weeks, while memory B cells have a life span of decades. Therefore, the presence of serum antibodies is not always a reliable indicator of B cell memory and comprehensive monitoring of humoral immunity requires that both serum antibodies and memory B cells be assessed. The prevailing view is that resting memory B cells and B cell blasts in peripheral blood mononuclear cells (PBMC) cannot be cryopreserved without losing their antibody secreting function, and regulated high throughput immune monitoring of B cell immunity is therefore confined to—and largely limited by—the need to test freshly isolated PBMC. Using optimized protocols for freezing and thawing of PBMC, and four color ImmunoSpot® analysis for the simultaneous detection of all immunoglobulin classes/subclasses we show here that both resting memory B cells and B cell blasts retain their ability to secrete antibody after thawing, and thus demonstrate the feasibility of B cell immune monitoring using cryopreserved PBMC. [ABSTRACT FROM AUTHOR]

A promising trend in the diagnosis of systemic autoimmune diseases is the multiplex immune assay (MIA) of autoantibodies and other laboratory biomarkers using microchips. The aim of the work was to study the diagnostic and prognostic significance of MIA antinuclear antibody (ANA) profiles in systemic lupus erythematosus (SLE). 94 patients with SLE, 70 patients with other rheumatic diseases and 30 healthy donors were examined. ANA (antibodies to doublestranded - dsDNA, Sm, SS-A/Ro, SS-B/La antigens, nucleosomes, ribosomal protein P-RibP and ribonucleoprotein - RNP-70) were determined in the serum by MIA using the xMAP technology. In MIA, antibodies to dsDNA, Sm and RibP have a high diagnostic specificity (Sp) (95.0-99.0%) and a likelihood ratio of positive results (LR+) (9.67-15.0), i.e. are the most "useful" diagnostic tests, and antibodies to RNP-70, SS-A/Ro and nucleosomes are classified as "useful" tests for the diagnosis of SLE (Sp: 84.0-95.0%, LR+> 2.0). Determination of profiles from 3 or more antigen-specific ANA by MIA increases the Sp method to 98.0-100%, and the LR+ - to the maximum values. Profiles from 7 subpopulations of ANA (antibodies to dsDNA, Sm, RibP, SS-A/Ro,SS-B/La, nucleosomes and RNP-70, 57.9%, 71.9%, 82.5%, 61.4 %, 84.2%, 50.9%, 84.2%) were found in the chronic variant of SLE. In the acute course of the disease, 4 subpopulations of ANA are simultaneously detected (antibodies to dsDNA, Sm, SS-A/Ro and nucleosomes, 77.3%, 45.5%, 40.9% and 72.7%); in subacute course there are 2 subpopulations of ANA (antibodies to dsDNA and nucleosomes, 53.3% and 46.7%). The activity index of SLEDAI-2K positively correlates with the concentration of antibodies to dsDNA (r = 0.55, p < 0.05), nucleosomes (r = 0.65, p < 0.05), RibP (r = 0.32; p < 0.05) and Sm (r = 0.36, p < 0.05) in the blood. There was no reliable relationship between the production of varieties of ANA and the index of organ damage. Mucocutaneous disorders, lupus-nephritis and neurolupus were most often associated with the detection of antibodies to dsDNA (53.2-64.0%), nucleosomes (55.3-66.0%), SS-A/Ro (38.0-40.4%) and Sm (27.8-36.2%). MIA of ANA profiles is an important tool for implementing a personalized approach to diagnosis, evaluation of activity, course and clinical and immunologic subtypes of SLE., Competing Interests: The authors declare no conflict of interest.