The Role of the CD28 Family Receptors in T-Cell Immunomodulation.

The CD28 family receptors include the CD28, ICOS (inducible co-stimulator), CTLA-4 (cytotoxic T-lymphocyte antigen-4), PD-1 (programmed cell death protein 1), and BTLA (B- and T-lymphocyte attenuator) molecules. They characterize a group of molecules similar to immunoglobulins that control the immune response through modulating T-cell activity. Among the family members, CD28 and ICOS act as enhancers of T-cell activity, while three others-BTLA, CTLA-4, and PD-1-function as suppressors. The receptors of the CD28 family interact with the B7 family of ligands. The cooperation between these molecules is essential for controlling the course of the adaptive response, but it also significantly impacts the development of immune-related diseases. This review introduces the reader to the molecular basis of the functioning of CD28 family receptors and their impact on T-cell activity.

The role of the BTLA-HVEM complex in the pathogenesis of autoimmune diseases.

Autoimmune diseases constitute a heterogeneous group of disorders with one common feature - the loss of immune tolerance towards autoantigens. Due to the complexity of the pathogenesis of these diseases, there are still many open questions regarding their etiology. Therefore, scientists unceasingly search for new data hoping to detect dependable biomarkers and design safe and effective treatment. The research on immune checkpoints is in line with these scientific and clinical demands. Immune checkpoints may be the key to understanding the pathogenesis of many immunological disorders. BTLA-HVEM complex, the inhibitory immune checkpoint, has recently caught scientific attention as an important regulator in different immune contexts, including autoreactivity. So far, the BTLA-HVEM complex has been mainly studied in the context of cancer, but as numerous data show, it may also be a target in the treating of autoimmune diseases. In this review, we intend to focus on the mechanisms of BTLA-HVEM interactions in immune cells and summarize the available data in the context of autoimmunity.

T cells in IgA nephropathy: role in pathogenesis, clinical significance and potential therapeutic target.

BACKGROUND: Immunoglobulin A nephropathy (IgAN), the most frequent cause of primary glomerulonephritis worldwide, is an autoimmune disease with complex pathogenesis. In this review, we focus on T cells and summarize knowledge about their involvement in pathophysiology and treatment of IgAN METHODS: We reviewed the literature for (1) alterations of T cell subpopulations in IgAN, (2) experimental and clinical proofs for T cells' participation in IgAN pathogenesis, (3) clinical correlations with T cell-associated alterations, and (4) influence of drugs used in IgAN therapy on T cell subpopulations. RESULTS: We found that IgAN is characterized by higher proportions of circulatory Th2, Tfh, Th17, Th22 and γδ T cells, but lower Th1 and Treg cells. We discuss genetic and epigenetic makeup that may contribute to this immunological phenotype. We found that Th2, Th17 and Tfh-type interleukins contribute to elevated synthesis of galactose-deficient IgA1 (Gd-IgA1) and that the production of anti-Gd-IgA1 autoantibodies may be stimulated by Tfh cells. We described the roles of Th2, Th17, Th22 and Treg cells in the renal injury and summarized correlations between T cell-associated alterations and clinical features of IgAN (proteinuria, reduced GFR, hematuria). We detailed the impact of immunosuppressive drugs on T cell subpopulations and found that the majority of drugs have nonoptimal influence on T cells in IgAN patients. CONCLUSIONS: T cells play an important role in IgAN pathogenesis and are correlated with its clinical severity. Clinical trials with the drugs targeting the reported alterations of the T-cell compartment are highly desirable.

The immunomodulatory effect of ketamine in depression.

Major depression is one of the most frequent psychiatric conditions. Despite many available treatment methods, more than 30% of patients do not achieve remission, even after trying several antidepressants and augmentation strategies. S-enantiomer of ketamine, well-known anesthetic and analgesic, has been recently approved by Food and Drug Administration in the intranasal form as a new generation antidepressant. However, the mechanism in which ketamine reduces depressive symptoms in treatment-resistant depression patients is still not completely understood. There are several theories explaining how ketamine might reduce depressive symptoms, which have been described in detail; one of them is immunomodulatory effect of ketamine, according to the inflammatory theory of depression. In the review authors present and summarize studies showing ketamine effect on human immune system ex vivo and in vitro, including changes in cytokine levels, number, ratio and activity of various immune cell population and the correlation with clinical improvement in depressive symptoms. Most of the results confirm the anti-inflammatory effect of ketamine. There are only a few studies in the population of patients suffering from depression receiving ketamine, focused on correlation between immunological changes and clinical outcome of the therapy; further studies of that area are neccesary for understanding the immunomodulatory effect of ketamine in depression.

Evaluation of quantitative changes in regulatory T cells in peripheral blood of kidney transplant recipients with skin cancer after conversion to mTOR inhibitors.

INTRODUCTION: Immunosuppressive therapy, necessary for graft survival, has its clinical consequences with an increased risk of developing malignancies being one of them. It seems that the maintenance of a proper balance between cytotoxic and regulatory activity of the immune system may prevent graft rejection, and with a lower risk of cancer. AIM: To assess the quantitative changes in regulatory T cells (Tregs) in peripheral blood of kidney transplant recipients with post-transplantation skin neoplasm after conversion to mTOR inhibitors (mTORi) and to assess the incidence of secondary skin cancer in that group of patients. MATERIAL AND METHODS: Fourteen patients with post-transplant cutaneous malignancies converted to mTORi were included into the study. The control group consisted of eighteen patients maintained on immunosuppressive regimens without mTORi. The level of Tregs with a phenotype defined as CD4lowCD25high was measured before, and 6 months after, mTORi introduction. RESULTS: In all cases, 6 months after conversion, a significant decrease in the ratio of CD4+CD25+ to CD4lowCD25high from 6.52 to 4.29 was detected (p = 0.035). One patient converted to mTORi developed subsequent skin cancer, while in the control group, subsequent skin cancer was recognized in eight patients. Moreover, introducing mTORi significantly improved progression-free survival in this group of patients (p = 0.016). CONCLUSIONS: Introducing mTORi to the immunosuppressive regimen resulted in an increase in the number of regulatory cells without increasing the incidence of secondary skin cancer in the investigated group of patients.

Phenotype, proliferation and apoptosis of B lymphocytes in hemodialysis patients treated with recombinant human erythropoietin.

One of the major causes of disorders of the immune response in patients undergoing hemodialysis (HD) is weaker activity of their helper T lymphocytes (Th cells), mainly reduced proliferative capacity associated with decreased expression of key surface antigens. Since cooperation between Th and B lymphocytes is essential for B cell function, changes in Th cell phenotype and ability to proliferate or produce cytokines could directly translate into an impaired humoral response. Therefore, we investigated the T cell-dependent activity of B cells in HD patients focusing mainly on their proliferative kinetics, susceptibility to apoptosis and the ability to produce antibodies. Since our previous studies have shown the beneficial effects of recombinant human erythropoietin (rhEPO) on T lymphocytes, we also investigated the in vivo and in vitro influence of rhEPO on B cells. Our results show that B lymphocytes of HD patients, especially of those who are not treated with rhEPO, have reduced proliferative capacity in vitro, reflected in low number of cell divisions, decreased percentage of proliferating cells and an increased susceptibility to apoptosis. They are also characterized by impaired ability to produce immunoglobulins. We have found no significant changes in the expression of key antigens of B lymphocytes with the exception of IL-10R. Furthermore, we demonstrated a time- and health status-dependent impact of rhEPO on patient's B cells. Our results show possible mechanisms responsible for the deficiency of humoral responses in HD patients which, at least partially, can be modulated through the supplementation with rhEPO.

The role of vitamin D in the development of autoimmune diseases.

Witamina D, poza istotna rola w utrzymaniu homeostazy wapnia i metabolizmie kostnym, odgrywa wazna role w funkcjonowaniu ukladu odpornosciowego. Niedobór witaminy D wiaze sie z wieloma niekorzystnymi dla zdrowia skutkami, wlaczajac w to m.in. oslabienie odpornosci, czego skutkiem jest zwiekszona podatnosc na zakazenia wirusowe, bakteryjne oraz grzybicze. W artykule opisano podstawy metabolizmu witaminy D oraz jej role fizjologiczna, ze szczególnym uwzglednieniem wplywu na komórki ukladu odpornosciowego. Ze wzgledu na jej istotna role w regulacji odpowiedzi zapalnej oraz wytwarzaniu cytokin zwraca sie uwage na jej role w rozwoju chorób o podlozu autoimmunologicznym, takich jak cukrzyca typu 1, toczen rumieniowaty, reumatoidalne zapalenie stawów, stwardnienie rozsiane, nieswoiste zapalenia jelit, luszczyca, bielactwo, czy twardzina, w których witamina D ma potencjalne szerokie zastosowanie zarówno w prewencji, jak i wspomaganiu dzialan terapeutycznych.

Homeostatic 'bystander' proliferation of human peripheral blood B cells in response to polyclonal T-cell stimulation in vitro.

The mechanisms of maintenance of adequate numbers of B lymphocytes and of protective levels of immunoglobulins in the absence of antigenic (re)stimulation remain not fully understood. Meanwhile, our results presented here show that both peripheral blood naive and memory B cells can be activated strongly and non-specifically (in a mitogen-like fashion) in 5-day in vitro cultures of anti-CD3- or concanavalin A (Con A)-stimulated peripheral blood mononuclear cells of healthy people. This polyclonal, bystander activation of the B cells includes multiple divisions of most of them (assessed here by the flow cytometric technique of dividing cell tracking) and significant antibody [immunoglobulin M (IgM) and IgG] secretion. Observed proliferation of the CD19(+) B cells depends on contact with stimulated T helper (Th) cells (via CD40-CD40L interaction) and on the response of B cells to secreted interleukins IL-5, IL-10 and IL-4, and is correlated with the levels of these Th-derived molecules, while it does not involve the ligation of the BCR/CD19 complex. We suggest that the effect might reflect the situation occurring in vivo as the homeostatic proliferation of otherwise non-stimulated, peripheral B lymphocytes, providing an always ready pool for efficient antibody production to any new (or cognate) antigen challenge.

Influence of hemodialysis on circulating CD4(low)CD25 (high) regulatory T cells in end-stage renal disease patients.

OBJECTIVE: Immunodeficiency of end-stage renal disease (ESRD) is caused by several factors including uremic toxins and biocompatibility reactions due to the repeated hemodialysis (HD) procedure. It has also been suggested that poor T cell responses could be associated with the increased number of regulatory T cells (Tregs) which are necessary to limit the function of activated T cells. The aim of the study was to determine the proportion of CD4(+)CD25(+) cells (activated T cells) to CD4(low)CD25(high) cells (Tregs) within the CD4(+) population in ESRD patients. PATIENTS AND METHODS: Two groups of ESRD patients, predialysis patients treated conservatively and patients undergoing hemodialysis (HD), as well as healthy controls were included in the study. Percentages of activated and regulatory T cells were determined ex vivo with flow cytometry based on the expression of CD4 and CD25 antigens. RESULTS AND CONCLUSIONS: HD patients showed an increased percentage of CD4(+)CD25(+) cells when compared with healthy controls, while there was no difference in the percentage of CD4(low)CD25(high) cells between the patient groups. In our opinion, the repeated hemodialysis procedure significantly disturbs the balance between activated T cells and regulatory T cells in ESRD patients. Lack of Treg mobilization and chronic stimulation of T cells may contribute to the immune deficiency observed in these patients.

Peptides targeting the BTLA-HVEM complex can modulate T cell immune response.

Immune checkpoints secure the proper function of the immune system and the maintenance of the BTLA-HVEM complex, an inhibitory immune checkpoint, is one of the pathways vital for T cell responsiveness to various stimuli. The present study reports the immunomodulatory potential of five peptides targeting the BTLA-HVEM complex on the activity of human T cells. Isolated T cells were exposed to the peptides alone or combined with CD3/CD28 mAb for 72 h or 120 h. The flow cytometry was used to evaluate the activation markers (CD69, CD62L, CD25), changes within the T cell memory compartment, proliferation rate, and apoptosis of T cells. The immunomodulatory effect of the peptides was visible as an increase in the percentage of CD4+ and CD8+ T cells expressing CD69 or CD25, a boost in T cell proliferation, and shifts in the T cell memory compartment. Pep(2) and Pep(5) were the most promising compounds, displaying a putative immune-restoring function.

The influence of recombinant human erythropoietin on apoptosis and cytokine production of CD4+ lymphocytes from hemodialyzed patients.

Recombinant human erythropoietin (rhEPO) treatment of hemodialyzed (HD) patients normalizes the altered phenotype of CD4(+) lymphocytes and restores the balance of Th1/Th2 cytokines. We decided to test how the presence of rhEPO in cell culture modulates cytokine production of CD4(+) lymphocytes in HD patients with stable hemoglobin level and expression of activation antigens of stimulated CD4(+) lymphocytes similar to those observed in healthy individuals. We also tested whether the presence of rhEPO in cell culture protects stimulated CD4(+) lymphocytes of HD patients from apoptosis. Peripheral blood mononuclear cells (PBMC) of HD patients were stimulated with an immobilized anti-CD3 antibody with or without addition of rhEPO. The percentage of apoptotic CD4(+) lymphocytes and the level of Th1/Th2 cytokines in culture supernatants were measured with flow cytometry. HD patients showed a decrease in the percentage of apoptotic CD4(+) cells after stimulation with the anti-CD3 antibody combined with rhEPO. The level of IFN-γ and IL-10 was increased while the level of TNF-α was decreased in the presence of rhEPO in cell culture from HD patients. These results confirm the role of rhEPO signaling in T lymphocytes of HD patients.

The immunomodulatory effect of lithium as a mechanism of action in bipolar disorder.

Bipolar disorder (BD) is a chronic mental disorder characterized by recurrent episodes of mania and depression alternating with periods of euthymia. Although environmental and genetic factors have been described, their pathogenesis is not fully understood. Much evidence suggests a role for inflammatory mediators and immune dysregulation in the development of BD. The first-line treatment in BD are mood-stabilizing agents, one of which is lithium (Li) salts. The Li mechanism of action is not fully understood, but it has been proposed that its robust immunomodulatory properties might be one of the mechanisms responsible for its effectiveness. In this article, the authors present the current knowledge about immune system changes accompanying BD, as well as the immunomodulatory effect of lithium. The results of studies describing connections between immune system changes and lithium effectiveness are often incoherent. Further research is needed to understand the connection between immune system modulation and the therapeutic action of lithium in BD.

Hemodialysis affects phenotype and proliferation of CD4-positive T lymphocytes.

CD4(+) T lymphocytes of patients with chronic kidney disease (CKD) are characterized by reduced levels of crucial surface antigens and changes in the cell cycle parameters. Recombinant human erythropoietin (rhEPO) normalizes their altered phenotype and proliferative capacity. Mechanisms leading to the deficient responses of T lymphocytes are still not clear but it is postulated that immunological changes are deepened by hemodialysis (HD). Study of activation parameters of CD4(+) T lymphocytes in hemodialyzed and predialysis CKD patients could bring insight into this problem. Two groups of patients, treated conservatively (predialysis, PD) and hemodialyzed (HD), as well as healthy controls, were included into the study; neither had received rhEPO. Proportions of main CD4(+)CD28(+), CD4(+)CD25(+), CD4(+)CD69(+), CD4(+)CD95(+), and CD4(+)HLA-DR(+) lymphocyte subpopulations and proliferation kinetic parameters were measured with flow cytometry, both ex vivo and in vitro. No differences were seen in the proportions of main CD4(+) lymphocyte subpopulations (CD4(+)CD28(+), CD4(+)CD25(+), CD4(+)HLA-DR(+), CD4(+)CD69(+), CD4(+)CD95(+)) between all examined groups ex vivo. CD4(+) T lymphocytes of HD patients exhibited significantly decreased expression of co-stimulatory molecule CD28 and activation markers CD25 and CD69 after stimulation in vitro when compared with PD patients and healthy controls. HD patients showed also decreased percentage of CD4(+)CD28(+) lymphocytes proliferating in vitro; these cells presented decreased numbers of finished divisions after 72 h of stimulation in vitro and had longer G0→G1 time when compared to healthy controls. CD4(+) T lymphocytes of PD patients and healthy controls were characterized by similar cell cycle parameters. Our study shows that repeated hemodialysis procedure influences phenotype and proliferation parameters of CD4(+) T lymphocytes.

T cell subpopulations and cytokine levels in hemodialysis patients.

HD patients have impaired adaptive immune responses, which might depend on the primary cause of chronic kidney disease (CKD). We analyzed percentages of T cells subpopulations with the expression of CD69, CD25, CD95, and HLA-DR antigens in HD patients to determine the status of T cell activation. Also, we determined serum levels of cytokines: IL12p70, TNF, IL-10, IL-6, IL-1ß, IL-8. HD patients had increased percentages of CD4+CD25+, CD4+CD69+, CD4+HLA-DR+, CD8+CD69+, and CD8+HLA-DR+ cells compared to healthy people. Also, their IL-6 and IL-8 serum levels were higher. Changes in T cell subpopulations were seen in patients with diabetic nephropathy (DN) or ischemic nephropathy (IN) but not with glomerulonephritis (GN). HD patients dialyzed for more than six months had a lower percentage of CD4+CD69+, CD8+HLA-DR+, CD8+CD95+ cells, higher IL-12p70 levels, and lower IL-8 levels. Our results show that HD treatment and CKD cause influence T cell activation status.

The influence of Nigella sativa essential oil on proliferation, activation, and apoptosis of human T lymphocytes in vitro.

In previous work, we tested the immunomodulatory effect of Nigella sativa (NS) fatty oil. Our results demonstrated that unrefined, obtained by cold pressing black cumin seed oil inhibited lymphocytes' proliferation and induced their apoptosis in a dose-dependent manner. In this study, we examined the immunomodulatory properties of essential oil (EO) obtained from the NS seeds by hydrodistillation and its two main constituents: thymoquinone (TQ) and p-cymene. We analyzed the proliferation, activation phenotype, and apoptosis rates of human T lymphocytes stimulated with an immobilized monoclonal anti-CD3 antibody in the presence of serial ethanol dilutions of tested oil or serial distilled water dilutions of tested compounds with flow cytometry. Our results showed that NSEO significantly inhibited the proliferation of CD4+ and CD8+ T lymphocytes, induced cell death in a dose-dependent manner, and reduced the expression of CD28 and CD25 antigens essential for lymphocyte activation. TQ inhibited the proliferation of T lymphocytes and induced cell death, particularly in high concentrations. Meanwhile, p-cymene did not influence lymphocyte proliferation. However, its high concentration induced cell necrosis. These results show that the essential oil from Nigella sativa has powerful immunomodulatory properties, which, at least partially, are related to the TQ component.

Flow cytometric analysis of STAT5 phosphorylation and CD95 expression in CD4+ T lymphocytes treated with recombinant human erythropoietin.

Erythropoietin receptor (EPO-R) appears on the cell surface in the early stages of erythropoiesis. It also has been found on human T and B lymphocytes and monocytes suggesting that EPO could directly influence these cells. Moreover, earlier reports have shown that treatment with recombinant human (rh) EPO in chronic renal failure (CRF) patients improves interleukin-2 production and restores CD4+ T lymphocyte functions. We decided to investigate possibility of direct action of rhEPO on these cells in vitro by phosphorylated signal transducer and activator of transcription 5 (pSTAT5) detection and changes in CD95 antigen expression observation. Flow cytometry was used for detection of pSTAT5 and CD95 expression in CD4+ T lymphocytes treated with rhEPO. Our results show that presence of rhEPO in cell culture of lymphocytes stimulated with anti-CD3 antibody increases percentage of CD4+ T lymphocytes expressing pSTAT5. Stimulating effect of rhEPO was dose dependent. RhEPO presence also increases CD95 expression on these cells but still activated T lymphocytes are resistant to CD95-mediated apoptosis. These observations show that EPO is able to directly influence CD4+ T lymphocytes' signaling pathways.

Nigella sativa oil inhibits proliferation and stimulates apoptosis of human lymphocytes in vitro.

The study aimed to examine the in vitro influence of Nigella sativa oil on human lymphocytes. Cells were stimulated with a monoclonal anti-CD3 antibody in the presence of serial oil ethanol dilutions. Then their proliferation and apoptosis rates were assessed using flow cytometry. Our results demonstrate that the lowest dilutions (1:1 and 1:10) of Nigella sativa oil inhibited lymphocytes' proliferation. The number of cell divisions was 8, 1.25, 1.88 after stimulation with anti-CD3, or its combination with 1:1 and 1:10 oil dilution. The percentage of proliferating cells was 92.48%, 8.75%, 24.3% after stimulation with anti-CD3 antibody, or its combination with 1:1 and 1:10 oil dilution. The mean percentage of living cells was 81% after stimulation with anti-CD3, 13.6%, 19.9% in the presence of 1:1 and 1:10 oil dilution. The preliminary studies show that black seed oil has a potent antiproliferative and proapoptotic effect on human lymphocytes in vitro.

Erythropoietin receptor is expressed on human peripheral blood T and B lymphocytes and monocytes and is modulated by recombinant human erythropoietin treatment.

Erythropoietin receptor (EPO-R) appears on the cell surface in the early stages of erythropoiesis. It has also been found on endothelial cells and polymorphonuclear leukocytes, suggesting erythropoietin (EPO) role beyond erythropoiesis itself. Earlier reports have shown that treatment with recombinant human erythropoietin (rhEPO) in chronic renal failure (CRF) patients improves interleukin-2 production and restores the T lymphocyte function. We decided to investigate possible expression of EPO-R on circulating peripheral blood lymphocytes and monocytes of CRF patients in order to assess the possibility of rhEPO direct action on these cells. Flow cytometry was used for detection and quantification of EPO-R, and reverse transcription polymerase chain reaction for detection of the EPO receptor mRNA. Our results show for the first time the existence of EPO-R on cell surface of human T and B lymphocytes and monocytes as well as at the transcriptional activity of the EPO-R gene in these cells, both in healthy and CRF individuals. We have also found significant differences between the numbers of EPO-R molecules on T and B lymphocytes of CRF patients not treated and treated with rhEPO and healthy control. Discovery of EPO-R expression on human lymphocytes suggests that EPO is probably able to directly modulate some signaling pathways important for these cells.

Recombinant human erythropoietin treatment of chronic renal failure patients normalizes altered phenotype and proliferation of CD4-positive T lymphocytes.

Patients with chronic renal failure (CRF) receive recombinant human erythropoietin (rhEPO) for the correction of anemia. However, rhEPO also has an immunomodulatory effect. Detailed changes of phenotype and function of CD4(+) T lymphocytes in CRF patients receiving rhEPO have not been reported yet; their study may bring insight into understanding of this immunomodulatory action of rhEPO. Two groups of CRF patients were included into the study: those treated; and those not receiving rhEPO. The expression of activation markers on CD4(+) lymphocytes was measured with flow cytometry, both ex vivo and in vitro. The kinetics of CD4(+) T lymphocytes proliferation was calculated using a dividing cells tracing method and numerical approach. Significantly higher percentages of CD4(+)CD95(+), CD4(+)HLA-DR(+) cells, and lower percentages of CD4(+)CD69(+) and CD4(+)CD28(+) cells were observed in both rhEPO-treated and untreated patients when compared with healthy controls. Changes in the proportions of CD4(+)CD28(+) and CD4(+)HLA-DR(+) subpopulations were dependent on the type of rhEPO, being more pronounced for rhEPObeta. CD4(+) lymphocytes from untreated patients exhibited decreased expression of CD28 and CD69 after stimulation in vitro, whereas the expression of these antigens on lymphocytes of rhEPO-treated patients was similar to that observed in healthy controls. Fewer CD4(+)CD28(+) T lymphocytes of untreated patients proliferated in vitro; these cells had longer G0-->G1 time, which negatively correlated with surface expression of CD28. Our study confirms that rhEPO treatment normalizes activation parameters of CD4(+) T lymphocytes and their proliferative capacity, which could explain earlier described immunomodulatory effects of rhEPO in patients suffering from CRF.

Dendritic cells' characteristics in patients with treated systemic lupus erythematosus.

The systemic lupus erythematosus (SLE) is a chronic autoimmune disease related to a loss of immune tolerance against autoantigens that leads to tissue inflammation and organ dysfunction. Constant stimulation of dendritic cells (DC) with autoantigens is hypothesized to increase the B cells' activity which are involved in production of autoantibodies that play an essential role in the SLE development. We focused our study on detecting alterations in DCs at the cellular and molecular levels in patients with treated SLE, depending on the disease activity and treatment. In order to phenotype subpopulations of DCs, multicolor flow cytometry was used. Transcriptional changes were identified with quantitative PCR, while soluble cytokine receptors were assessed with the Luminex technology. We show that SLE patients display a higher percentage of activated myeloid DCs (mDCs) when compared to healthy people. Both, the mDCs and plasmacytoid DCs (pDCs) of SLE patients were characterized by changes in expression of genes associated with their maturation, functioning and signalling, which was especially reflected by low expression of regulatory factor ID2 and increased expression of IRF5. pDCs of SLE patients also showed increased expression of IRF1. There were also significant changes in the expression of APRIL, MBD2, and E2-2 in mDCs that significantly correlated with some serum components, i.e. anti-dsDNA antibodies or complement components. However, we did not find any significant differences depending on the disease activity. While the majority of available studies focuses mainly on the role of pDCs in the disease development, our results show significant disturbances in the functioning of mDCs in SLE patients, thus confirming mDCs' importance in SLE pathogenesis.