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Sarcoidosis is a systemic granulomatous disease that develops due to the Th1, Th17 and Treg lymphocytes disturbance. There is an assumption, that B cells and follicular T-helper (Tfh) cells may play an important role in this disorder, as well as in several other autoimmune diseases. The aim of this study was to determine CD19+ B cells subset distribution in the peripheral blood and to define disturbance in the circulating Tfh cells subsets in patients with sarcoidosis. The prospective comparative study was performed in 2016–2018, where peripheral blood B cell subsets and circulating Tfh cell subsets were analyzed in 37 patients with primarily diagnosed sarcoidosis and 35 healthy donors using multicolor flow cytometry. In the results of our study we found the altered distribution of peripheral B cell subsets with a predominance of “naïve” (IgD + CD27−) and activated B cell (Bm2 and Bm2′) subsets and a decreased frequency of memory cell (IgD+ CD27+ and IgD− CD27+) in peripheral blood of sarcoidosis patients was demonstrated. Moreover, we found that in sarcoidosis patients there are increased levels of B cell subsets, which were previously shown to display regulatory capacities (CD24+++ CD38+++ and CD5 + CD27−). Next, a significantly higher proportion of CXCR5-expressing CD45RA − CCR7+ Th cells in patients with sarcoidosis in comparison to the healthy controls was revealed, that represents the expansion of this memory Th cell subset in the disease. This is the first study to demonstrate the association between the development of sarcoidosis and imbalance of circulating Tfh cells, especially CCR4− and CXCR3-expressing Tfh subsets. Finally, based on our data we can assume that B cells and Tfh2- and Tfh17-like cells – most effective cell type in supporting B-cell activity, particularly in antibody production – may be involved in the occurrence and development of sarcoidosis and in several other autoimmune conditions. Therefore, we can consider these results as a new evidence of the autoimmune mechanisms in the sarcoidosis development.

Immunological testing for tuberculosis has been one of the most rapidly developing areas in the last decade. A new-generation immunological skin test, Diaskintest (DST), has been developed in the Russian Federation and successfully implemented into clinical practice since 2009. This article presents the results of a meta-analysis of publications reporting data on the use of the recombinant tuberculosis allergen DST (n = 121) from 2009 to 2019 included in Russian and international databases. The analysis included a total of 61 papers consistent with the study design, which cumulatively presented the results of 3,777,083 patients tested with DST (83.0%). The obtained data showed that the overall diagnostic sensitivity of the test in this population, regardless of age, was 86.0%, with 98.0% negative results. It was found that the intensity of the immune response of tuberculosis patients to specific ESAT-6 and CFP-10 antigens of DST may depend on the biological properties of the pathogen characteristic to various Mycobacterium tuberculosis genotypes, tuberculosis severity, and the presence of concomitant diseases. These factors are more prevalent in the adult population. In children, however, the test sensitivity reaches 100%. The proportion of positive DST results in HIV-positive patients tested for tuberculosis was 60.0%. The analysis showed that the accuracy (overall validity) of DST was 95.1% in the total studied population (95% confidence interval [CI]: 95.06-95.1) and 92.4% in HIV-positive patients (95% CI: 91.9-92.7).

Sarcoidosis and tuberculosis have many clinical and laboratory similarities, which allowed researchers to assume the presence of common pathogenetic mechanisms in the development of both diseases. Recently, much attention has been paid to investigate the autoimmune origins in these pathologies. The aim of this study is to find out the characteristics of the autoinflammatory immune response in sarcoidosis and tuberculosis. In patients with sarcoidosis (n = 93), tuberculosis (n = 28), and in healthy donors (n = 40), the serum anti-MCV concentration was measured by ELISA, and B cell subpopulations were analyzed by flow cytometry. Based on the results obtained, the formula ([B-naive%]\[B-memory%]) * ([B-CD38%] + [B-CD5%]) / [anti-MCV] was described. The increase in the calculated index by more than 5 units with a sensitivity of 80.00% and a specificity of 93.10% (AUC = 0.926) suggest the presence of the autoimmune component, which is more typical for sarcoidosis, rather than tuberculosis patients and may serve as a diagnostic criterion.

In the last 30 years, improvement of diagnostic methods enabled routine evaluation of small A-delta and C nerve fibers impairment, which results with the clinical condition known as a small-fiber neuropathy (SFN). This syndrome develops as a result of metabolic, toxic, immune-mediated, or genetic factors. The main clinical features include neuropathic pain and autonomic disturbance, which are occasionally disclaimed due to outstanding fatigue, daily performance decline, anxiety, and depression. As clinical, neurological, nerve conduction, and electromyography studies are commonly normal, diagnosis often depends on the finding of decreased intra-epidermal density of nerve fibers, per skin biopsy. This review highlights the etiology, clinical, diagnostic aspects, and SFN treatment.