SummaryNon-HLA antibodies (Abs) targeting vascular receptors are thought to have an impact on renal transplant injury. Anti-angiotensin II type 1-receptor-activating antibodies (anti-AT1R) have been mentioned to stimulate a severe vascular rejection, but the pretransplant screening has not been introduced yet. The aim of our study was to assess the incidence and importance of anti-AT1R antibodies and their influence on renal transplant in the 1st year of observation. We prospectively evaluated the presence of anti-AT1R antibodies in 117 consecutive renal transplant recipients in pre-and post-transplant screening. Anti-AT1R antibodies were observed in 27/117 (23%) of the analyzed recipients already before transplantation. The function of renal transplant was considerably worse in anti-AT1R(+) group. The patients with anti-AT1R Abs >9 U/ml lost their graft more often. Biopsy-proven AR was described in 4/27 (15%) pts in the anti-AT1R(+) group and 13/90 (14.4%) in the anti-AT1R(À) group, but more severe cases of Banff IIB or antibody-mediated rejection (AMR) were more often observed in anti-AT1R (+) 4/27 (15%) vs. 1/90 (1.1%) in anti-AT1R(+) (P = 0.009). Patients with anti-AT1R Abs level >9 U/ml run a higher risk of graft failure independently of classical immunological risk factors. The recipients with anti-AT1R Abs developed more severe acute rejections described as IIB or AMR in Banff classification. More recipients among the anti-AT1R-positive ones lost the graft. Our study suggests monitoring of anti-AT1R Abs before renal transplantation for assessment of immunologic risk profiles and the identification of patients highly susceptible to immunologic events, graft failure, and graft loss.

Serum complement cascade, a part of innate immunity required for host protection against invading pathogens, is also a mediator of various forms of disease and injury. It is activated by classical, lectin, and alternative pathways that lead to activation of C3 component by C3 convertases, release of C3b opsonin, C5 conversion and eventually membrane attack complex formation. The tightly regulated activation process yields also C3a and C5a anaphylatoxins, which target a broad spectrum of immune and non-immune cells. The review discusses the involvement of the complement cascade in kidney disease pathogenesis and injury. The role of the complement pathways in autoantibody-mediated forms of glomerulonephritis (lupus nephritis, anti-glomerular basement membrane disease, anti-neutrophil cytoplasmic autoantibody-induced or membranoproliferative glomerulonephritis, membranous nephropathy), C3 glomerulopathy, atypical forms of hemolytic uremic syndrome, ischemic-reperfusion injury of transplanted kidney, and antibody-mediated renal allograft rejection are discussed. The disturbances in complement activation and regulation with underlying genetics are presented and related to observed pathology. Also promising strategies targeting the complement system in complement-related disorders are mentioned.

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The available clinical as well as experimental studies implicate participation of T regulatory (Treg) subsets in the pathogenesis and course of systemic lupus erythematosus (SLE). Introduction of the CD4+CD25+CD127− and CD4+CD25+Foxp3+ regulatory subpopulations analysis into immunological processes assessment and disease activation prognosis in patients with lupus nephritis (LN) may improve monitoring of disease activity and enable an early, and thus more effective, therapeutic treatment. The main goal of the study was to investigate whether the quantitative changes of Treg subpopulations are related to the clinical status of patients with LN. Fifty-four adult SLE patients divided into two groups according to their SLEDAI and renal SLEDAI scores were enrolled into the study. Subpopulations of CD4+CD25+CD127− and CD4+CD25+Foxp3+ phenotypes were determined by flow cytometry. The control group had higher absolute number of CD4+CD25+Foxp3+ cells compared with the study group (p < 0.001). Also, significant inverse correlation in the absolute number of CD4+CD25+Foxp3+ cells and SLEDAI score was observed. There were significant differences in the percentage and absolute number of CD4+CD25+Foxp3+ lymphocytes between active and non-active LN groups. The study group had statistically lower values of CD4+CD25+CD127− cells, both in the percentage (p < 0.001) as well as their absolute number (p = 0.014) compared to the control group. There were also statistically significant positive correlations between the absolute number of CD4+CD25+CD127− and CD4+CD25+Foxp3+ Tregs. In conclusion: (1) reduction in the number of regulatory CD4+CD25+Foxp3+ cells is a promising indicator of the activity of SLE, particularly of renal involvement; (2) determination of the number of regulatory cells using the CD4+CD25+CD127− phenotype is unreliable in patients with SLE.

Background: Initially, there were no data on the safety of COVID-19 vaccines in lactating women. The aim of our study was to evaluate the immune response to COVID-19 vaccinations in breastfeeding women. Methods: The study included 32 breastfeeding women who, regardless of the study, had decided to be vaccinated. Maternal serum and breast milk samples were simultaneously collected on days 8 ± 1, 22 ± 2, 29 ± 3, and 43 ± 4 after the first dose of the vaccine. The immune response was assessed by determining the presence of anti-SARS-CoV-2 IgG and IgA. Results: The breast milk IgG level was detectable (6.50 ± 6.74, median 4.7, and maximum 34.2 BAU/mL) and highly correlated to serum IgG level (rS 0.89; p < 0.001). The breast milk ratio of IgA to the cut-off value was higher in serum IgA-positive (4.18 ± 3.26, median 2.8, and maximum >10) than in serum IgA-negative women (0.56 ± 0.37, median 0.5, and maximum 1.6; p < 0.001). The highest concentrations of serum and breast milk antibodies were observed on day 29 ± 3 with a decrease on day 43 ± 4. Conclusion: The immune response to the vaccination against SARS-CoV-2 is strongest 7 ± 3 days after the second dose of the vaccine. Lactating mothers breastfeeding their children after vaccination against SARS-CoV-2 may transfer antibodies to their infant.

Successful long-term kidney allograft survival with parallel reduction of complications resulting from prolonged immunosuppressive treatment is a goal in kidney transplantation. We studied the immune changes in cell phenotypes and gene expression induced by kidney transplantation. Our goal was to find a phenotypic and/or transcriptional pattern that might be considered prognostic for the kidney transplant outcome. The analysis was performed prospectively on 36 KTx recipients sampled during the first year and followed for five years after transplantation and on 40 long-term KTx recipients (7.9 ± 2.2 y. post-KTx). The research involved flow cytometry assessment of lymphocyte subpopulations (including Tregs and CD3+CD8+CD28− lymphocytes) and gene expression analysis of immune-related genes (CD4, CD8, CTLA4, GZMB, FOXP3, IL10, IL4, ILR2A, NOTCH, PDCD1, PRF1, TGFB, and TNFA). The analysis of patterns observed over the first post-KTx year was confronted with control, pretransplant, and long-term transplant results. Treg counts at months one and three post-KTx correlated positively with the current and future allograft function. FOXP3 gene expression at month one post-KTx was also associated with long-term allograft function. The KTx-induced CD3+CD8+CD28− population correlated with GZMB and PRF1 expression and suggested their cytotoxic properties. The size of the Treg population and regulatory FOXP3 gene expression in the early period after transplantation are associated with kidney transplant outcome. The outlined predictive power of the Treg population needs to be investigated further to be confirmed as one of the immune monitoring strategies that may help achieve the best long-term kidney allograft outcomes.

The results of studies on the CD3+CD8+CD28− cells in SLE are inconsistent since several analyses describe CD3+CD8+CD28− as either immunosuppressive or cytotoxic. The aim of this study is to inquire whether the quantitative changes of CD3+CD8+CD28− T lymphocytes subpopulation are related to the clinical status of patients with lupus nephritis. Evaluation of Foxp3 expression on CD3+CD8+CD28− cells may shed some light on functional properties of these cells. 54 adult SLE patients and 19 sex and age matched healthy volunteers were enrolled in the study. There were 15 patients in inactive (SLEDAI ≤ 5) and 39 in active (SLEDAI > 5) phase of disease. We determined absolute count of CD3+CD8+CD28− and CD3+CD8+CD28−Foxp3+ subpopulations by flow cytometry. We observed a statistically significant increase in absolute count and percentage of CD3+CD8+CD28− in SLE patients compared to HC (p < 0.001). Moreover there was significant positive correlation between increasing absolute count of CD3+CD8+CD28− cells and disease activity measured by SLEDAI (rs = 0.281, p = 0.038). Active LN patients had increased absolute count of CD3+CD8+CD28− cells compared to HC. Positive correlation of CD3+CD8+CD28− number with disease activity, and lack of Foxp3 expression on these cells, suggests that CD3+CD8+CD28− lymphocytes might be responsible for an increased proinflammatory response in the exacerbation of SLE.