Chronic Active Antibody-Mediated Rejection Following COVID-19 Infection in a Kidney Transplant Recipient: A Case Report.

Kidney transplant recipients who develop coronavirus disease 2019 (COVID-19) are at increased risk of life-threatening illness, which often requires reducing immunosuppression despite the potential risk of causing an allograft rejection. Herein, we describe the clinical presentation and course of a kidney transplant recipient who acquired COVID-19 and was hospitalized with severe symptoms and hypoxemia. Upon admission, the patient was found to have elevated de novo donor-specific antibodies (DSA) yielding a positive cytotoxicity crossmatch and concurrent elevated plasma donor-derived cell-free DNA (dd-cfDNA) level, indicating a possible ongoing rejection despite improvement in his serum creatinine. Because of persistent positive COVID-19 tests and stable serum creatinine, a kidney allograft biopsy was initially deferred and his dd-cfDNA and DSA were monitored closely postdischarge. Three months later, because of persistent elevated dd-cfDNA and positive DSA, a kidney allograft biopsy was performed, which showed chronic active antibody-mediated rejection. Accordingly, the patient was treated with intravenous immunoglobulin and his maintenance immunosuppressive regimen was increased.

Cytomegalovirus (CMV) Epitope-Specific CD4+ T Cells Are Inflated in HIV+ CMV+ Subjects.

Select CMV epitopes drive life-long CD8+ T cell memory inflation, but the extent of CD4 memory inflation is poorly studied. CD4+ T cells specific for human CMV (HCMV) are elevated in HIV+ HCMV+ subjects. To determine whether HCMV epitope-specific CD4+ T cell memory inflation occurs during HIV infection, we used HLA-DR7 (DRB1*07:01) tetramers loaded with the glycoprotein B DYSNTHSTRYV (DYS) epitope to characterize circulating CD4+ T cells in coinfected HLA-DR7+ long-term nonprogressor HIV subjects with undetectable HCMV plasma viremia. DYS-specific CD4+ T cells were inflated among these HIV+ subjects compared with those from an HIV- HCMV+ HLA-DR7+ cohort or with HLA-DR7-restricted CD4+ T cells from the HIV-coinfected cohort that were specific for epitopes of HCMV phosphoprotein-65, tetanus toxoid precursor, EBV nuclear Ag 2, or HIV gag protein. Inflated DYS-specific CD4+ T cells consisted of effector memory or effector memory-RA+ subsets with restricted TCRß usage and nearly monoclonal CDR3 containing novel conserved amino acids. Expression of this near-monoclonal TCR in a Jurkat cell-transfection system validated fine DYS specificity. Inflated cells were polyfunctional, not senescent, and displayed high ex vivo levels of granzyme B, CX3CR1, CD38, or HLA-DR but less often coexpressed CD38+ and HLA-DR+ The inflation mechanism did not involve apoptosis suppression, increased proliferation, or HIV gag cross-reactivity. Instead, the findings suggest that intermittent or chronic expression of epitopes, such as DYS, drive inflation of activated CD4+ T cells that home to endothelial cells and have the potential to mediate cytotoxicity and vascular disease.

HLA-DR and HLA-DP restricted epitopes from human cytomegalovirus glycoprotein B recognized by CD4+ T-cell clones from chronically infected individuals.

PURPOSE: Helper CD4(+) T cells presumably play a major role in controlling cytomegalovirus (CMV) by providing help to specific B and CD8(+) cytotoxic T cells, as well as through cytotoxicity-mediated mechanisms. Since CMV glycoprotein B (gB) is a major candidate for a subunit vaccine against CMV, we searched for gB-epitopes presented by human leukocyte antigen (HLA)-class II molecules. METHODS: Dendritic cells obtained from CMV-seropositive donors were loaded with a recombinant gB and co-cultured with autologous CD4(+) T cells. Microcultures that specifically recognized gB were cloned by limiting dilution using autologous Epstein-Barr virus (EBV)-immortalized B cells pulsed with gB as antigen-presenting cells. To pinpoint precisely the region encoding the natural epitope recognized by a given CD4(+) clone, we assessed the recognition of recombinant Escherichia coli expressing gB-overlapping polypeptides after their processing by autologous EBV-B cells. RESULTS: We isolated several gB-specific CD4(+) T-cell clones directed against peptides gB(190-204), gB(396-410), gB(22-36) and gB(598-617) presented by HLA-DR7, HLA-DP10 and HLA-DP2. While their precise role in controlling CMV infection remains to be established, gB-specific CD4(+) T cells are likely to act by directly targeting infected HLA-class II cells in vivo, as suggested by their recognition of EBV-B cells infected by the Towne CMV strain. CONCLUSIONS: The characterization of such gB-epitopes presented by HLA-class II should help to understand the contribution of CD4(+) T-cell responses to CMV and may be of importance both in designing a vaccine against CMV infection and in immunomonitoring of subjects immunized with recombinant gB or with vectors encoding gB.

Race-specific type 1 diabetes risk of HLA-DR7 haplotypes.

The aim of this study was to test the hypothesis that closely related human leukocyte antigen (HLA) haplotypes containing the DRB1*07:01 gene ['DR7' (DRB1*07:01-DQA1*02:01-DQB1*02:01g or DRB1*07:01-DQA1*03:01-DQB1*02:01g) haplotypes] derived from European and African populations differ in their genetic susceptibility for type 1 diabetes (T1D) depending on the DQ-α molecule present. A combined total of 98 African American T1D patients from the Type 1 Diabetes Genetics Consortium and from Children's Hospital and Research Center Oakland were genotyped for the HLA class II loci DRB1, DQA1, and DQB1. DNA samples extracted from newborn blood spot cards from African Americans born in California (n = 947) were used as a population-based control group. Among African American cases, the European-derived DRB1*07:01-DQA1*02:01-DQB1*02:01g haplotype was protective for T1D risk (odds ratio (OR) = 0.34; 95% confidence interval (CI) 0.14-0.78; P < 0.011), but the African-derived DRB1*07:01-DQA1*03:01-DQB1*02:01g haplotype increased T1D risk (OR = 3.96; 95% CI 1.94-8.08; P < 5.5E-05). The effect of DRB1*07:01-DQB1*02:01g on T1D susceptibility depends on the DQA1 allele. DRB1*07:01-DQA1*02:01-DQB1*02:01g is protective for T1D; however, the presence of DQA1*03:01 on the DRB1*07:01-DQB1*02:01g haplotype not only renders the DR7 haplotype not protective but also creates a haplotype with significant T1D risk. These data underscore the importance of assessing genetic effects within ethnic context.

Autism spectrum disorders are associated with an elevated autoantibody response to tissue transglutaminase-2.

We report that a significant number of autistic children have serum levels of IgA antibodies above normal to the enzyme tissue transglutaminase II (TG2), and that expression of these antibodies to TG2 is linked to the (HLA)-DR3, DQ2 and DR7, DQ2 haplotypes. TG2 is expressed in the brain, where it has been shown to be important in cell adhesion and synaptic stabilization. Thus, these children appear to constitute a subpopulation of autistic children who fall within the autism disease spectrum, and for whom autoimmunity may represent a significant etiological component of their autism.

Injections of Clostridium botulinum neurotoxin A may cause thyroid complications in predisposed persons based on molecular mimicry with thyroid autoantigens.

A woman with Hashimoto's thyroiditis, under replacement L-T4, repeatedly experienced, over a 10-year period, elevations of serum TSH after eyelid injections of Clostridium botulinum neurotoxin A (Btx). We hypothesized a link between Btx injections and TSH elevations via molecular mimicry, and aimed to verify our hypothesis. Using an in silico approach, we searched first for amino acid sequence homology between Btx and thyroid autoantigens, and next for HLA binding motifs within homologous segments. We found that (i) Btx and thyroid autoantigens share amino acid sequence homology; (ii) some homologous regions contain epitopes of both Btx and thyroid autoantigens; (iii) some of such regions contain HLA-DR3 and/or HLA-DR7 binding motifs, which predominate over other HLA-DRs. This is relevant because the patient's HLA-DR haplotype was DR3/DR7. In conclusion, clinical and bioinformatics data suggest a possible pathogenetic link between Btx and autoimmune thyroid diseases. Considering the wide and increasing medical and dermocosmetic use of Btx, and the frequently subclinical course of autoimmune thyroid diseases, we think that thyroid "complications" may pass frequently undetected in Btx-treated persons.

The role of glutamic or aspartic acid in position four of the epitope binding motif and thyrotropin receptor-extracellular domain epitope selection in Graves' disease.

CONTEXT: Development of Graves' disease (GD) is related to HLA-DRB1*0301 (DR3),and more specifically to arginine at position 74 of the DRB1 molecule. The extracellular domain (ECD) of human TSH receptor (hTSH-R) contains the target antigen. OBJECTIVE AND DESIGN: We analyzed the relation between hTSH-R-ECD peptides and DR molecules to determine whether aspartic acid (D) or glutamic acid (E) at position four in the binding motif influenced selection of functional epitopes. RESULTS: Peptide epitopes from TSH-R-ECD with D or E in position four (D/E+) had higher affinity for binding to DR3 than peptides without D/E (D/E-) (IC(50) 29.3 vs. 61.4, P = 0.0024). HLA-DR7, negatively correlated with GD, and DRB1*0302 (HLA-DR18), not associated with GD, had different profiles of epitope binding. Toxic GD patients who are DR3+ had higher responses to D/E+ peptides than D/E- peptides (stimulation index 1.42 vs. 1.22, P = 0.028). All DR3+ GD patients (toxic + euthyroid) had higher responses, with borderline significance (Sl; 1.32 vs. 1.18, P = 0.051). Splenocytes of DR3 transgenic mice immunized to TSH-R-ECD responded to D/E+ peptides more than D/E- peptides (stimulation index 1.95 vs. 1.69, P = 0.036). Seven of nine hTSH-R-ECD peptide epitopes reported to be reactive with GD patients' peripheral blood mononuclear cells contain binding motifs with D/E at position four. CONCLUSIONS: TSH-R-ECD epitopes with D/E in position four of the binding motif bind more strongly to DRB1*0301 than epitopes that are D/E- and are more stimulatory to GD patients' peripheral blood mononuclear cells and to splenocytes from mice immunized to hTSH-R. These epitopes appear important in immunogenicity to TSH-R due to their favored binding to HLA-DR3, thus increasing presentation to T cells.

Correlation of blood T cell and antibody reactivity to myelin proteins with HLA type and lesion localization in multiple sclerosis.

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the CNS. The numbers of autoimmune T cells and Abs specific for proteins of CNS myelin are increased in the blood in some patients with MS. The aim of this study was to investigate whether there are correlations between the specificity of the autoimmune responses in the blood, the HLA molecules carried by the patient, and the clinical features of MS, because studies on experimental autoimmune encephalomyelitis, an animal model of MS, indicate that autoimmune responses targeting particular myelin proteins and the genetic background of the animal play a role in determining the pattern of lesion distribution. We tested blood T cell immunoreactivity to myelin proteins in 100 MS patients, 70 healthy controls, and 48 patients with other neurological disorders. Forty MS patients had strongly increased T cell reactivity to one or more myelin Ags. In these 40 patients, the most robust correlation was between CD4(+) T cell reactivity to myelin proteolipid protein residues 184-209 (PLP(184-209)) and development of lesions in the brainstem and cerebellum. Furthermore, carriage of HLA-DR4, -DR7, or -DR13 molecules by MS patients correlated with increased blood T cell immunoreactivity to PLP(184-209), as well as the development of lesions in the brainstem and cerebellum. Levels of PLP(190-209)-specific Abs in the blood also correlated with the presence of cerebellar lesions. These findings show that circulating T cells and Abs reactive against specific myelin Ags can correlate with lesion distribution in MS and suggest that they are of pathogenic relevance.

CD4+ T cells specific for glycoprotein B from cytomegalovirus exhibit extreme conservation of T-cell receptor usage between different individuals.

Antigen-specific CD8(+) cytotoxic T cells often demonstrate extreme conservation of T-cell receptor (TCR) usage between different individuals, but similar characteristics have not been documented for CD4(+) T cells. CD4(+) T cells predominantly have a helper immune role, but a cytotoxic CD4(+) T-cell subset has been characterized, and we have studied the cytotoxic CD4(+) T-cell response to a peptide from human cytomegalovirus glycoprotein B presented through HLA-DRB*0701. We show that this peptide elicits a cytotoxic CD4(+) T-cell response that averages 3.6% of the total CD4(+) T-cell repertoire of cytomegalovirus-seropositive donors. Moreover, CD4(+) cytotoxic T-cell clones isolated from different individuals exhibit extensive conservation of TCR usage, which indicates strong T-cell clonal selection for peptide recognition. Remarkably, this TCR sequence was recently reported in more than 50% of cases of CD4(+) T-cell large granular lymphocytosis. Immunodominance of cytotoxic CD4(+) T cells thus parallels that of CD8(+) subsets and suggests that cytotoxic effector function is critical to the development of T-cell clonal selection, possibly from immune competition secondary to lysis of antigen-presenting cells. In addition, these TCR sequences are highly homologous to those observed in HLA-DR7(+) patients with CD4(+) T-cell large granular lymphocytosis and implicate cytomegalovirus as a likely antigenic stimulus for this disorder.

Modulation of allergic response by gene-environment interaction: olive pollen allergy.

This article summarizes the most important advances of recent years in the field of gene-environment interaction in allergic response. It specifically examines sensitization to olive pollen as an example of one of the main causes of allergic disease in the Mediterranean area. The presence of at least 20 proteins with allergic activity has been demonstrated in olive pollen, and 10 of these have been characterized (Ole e 1 to Ole e 10). Ole e 1, which is considered to be the majority allergen (causing sensitization in more than 70% of patients), has been the subject of many studies looking for risk factors and ways to protect against sensitization. Markers of the major histocompatibility complex and other genetic loci associated with the allergic response have been analyzed using population-based, family-based, and functional approaches, which have revealed the involvement of genetic regulation in this type of response. Furthermore, evaluation of environmental factors and their relationship with genetic factors is essential when attempting to understand this type of disease. In this review, we provide examples of how exposure to high doses of olive pollen allergen in a specific genetic context can trigger different allergic conditions (from asthma to nonresponse). We stress the importance of evaluating these factors in order to modulate this response correctly.

Shared MHC class II-dependent melanoma ribosomal protein L8 identified by phage display.

Antigens recognized by T helper (Th) cells in the context of MHC class II molecules have vaccine potential against cancer and infectious agents. We have described previously a melanoma patient's HLA-DR7-restricted Th cell clone recognizing an antigen, which is shared among melanoma and glioma cells derived from various patients. Here, this antigen was cloned using a novel antigen phage display approach. The antigen was identified as the ribosomal protein L8 (RPL8). A peptide of RPL8 significantly stimulated proliferation and/or cytokine expression of the Th cell clone and lymphocytes in four of nine HLA-DR7(+) melanoma patients but not in healthy volunteers. The RPL8 antigen may represent a relevant vaccine target for patients with melanoma, glioma, and breast carcinoma whose tumors express this protein.

[Influence of genetic and phenotypical factors on the efficiency of the vaccination of young children against diphtheria and measles].

The child's sex was shown to influence the character of antibody formation only after immunization against diphtheria with live measles vaccine: girls exhibited stronger reaction to vaccination than boys. Children of different gender were found to have characteristic HLA DR markers of humoral immune response to diphtheria toxoid and measles vaccine. HLA DR7 proved to be the marker of low production of antibodies to diphtheria toxoid and measles vaccine in boys.

Phenotype and function of monocyte derived dendritic cells in chronic hepatitis B virus infection.

The antiviral T cell failure of patients with chronic hepatitis B virus (HBV) infection was suggested to be caused by a T cell stimulation defect of dendritic cells (DC). To address this hypothesis, monocyte derived DC (MDDC) of patients with chronic or resolved acute HBV infection and healthy controls were studied phenotypically by FACS analyses and functionally by mixed lymphocyte reaction, ELISA, ELISpot and proliferation assays of MDDC cultures or co-cultures with an allogeneic HBc-specific Th cell clone. HBV infection of MDDC was studied by quantitative PCR. MDDC from HBV patients seemed to be infected by the HBV, showed a reduced surface expression of HLA DR and CD40 and exhibited a reduced secretion of IL12p70 in response to HBcAg but not to LPS, as compared to control MDDC. However, after cytokine induced maturation, MDDC from HBV patients revealed an unimpaired phenotype. Moreover, the T cell stimulatory capacity of HBV-DC was intact, since (i) the induction of allospecific proliferative and IFN-gamma responses was not affected in HBV-MDDC, and (ii) HLA DR7 restricted stimulation of an allogeneic HBc-specific Th cell clone was not impaired by HBV-MDDC compared to control MDDC. It is hypothesized that HBV infection of DC might lead to minor phenotypic and functional alterations without significantly affecting their antiviral Th cell stimulatory capacity.

A CD4+, HLA-DR7-restricted T-helper lymphocyte clone recognizes an antigen shared by human malignant melanoma and glioma.

CD4(+) Th cells that are restricted by MHC class II molecules play an important role in the induction of antitumor immune responses. We have established a stable CD4(+) Th cell clone (Th35-1A) from the PBMCs of a patient with primary cutaneous melanoma. The Th cell clone is noncytolytic and proliferates specifically in the presence of irradiated autologous melanoma cells or autologous EBV-transformed B cells pulsed with melanoma tumor cell lysates. Th35-1A produces IFN-gamma (a Th1-type cytokine) after autologous tumor cell stimulation, and its proliferative reactivity is HLA class II-restricted. Th cells showed helper activity for PWM responses of PBMCs. Using a panel of HLA class II-matched and unmatched EBV-B cells as APCs and allogeneic melanoma tumor cell lysate as stimulant, DR7 was delineated as the HLA class II restriction element used by the Th cell clone. In agreement with these results, transfection of an allogeneic melanoma cell line with HLA-DR7 isolated from autologous EBV-B cells rendered the cell line stimulatory for Th35-1A cells. Specificity studies using autologous EBV-B cells (EBV-B35) pulsed with a panel of allogeneic tumor cell lysates of various tissue origins indicated that the Th cell clone recognizes an antigen shared by melanoma and glioma cells. The availability of the Th cell clone may lead to the development of new therapies against melanoma, using adoptive Th cell transfer and/or active immunization with a shared Th cell antigen.

Donor-derived b2a2-specific T cells for immunotherapy of patients with chronic myeloid leukemia.

The BCR-ABL fusion proteins, b2a2 and b3a2, are potential targets for a beneficial graft-versus-leukemia (GVL) effect after allogeneic stem cell transplantation for chronic myeloid leukemia (CML). This study demonstrates that CD4+ T cells specific to the b2a2 peptide can be generated from a normal allogeneic stem cell transplant donor after stimulation with monocyte-derived dendritic cells (Mo-DC) using culture conditions applicable to clinical use. Stimulation of donor T-cell enriched mononuclear cells (MNC) with b2a2-pulsed Mo-DC produced approximately 3 x 10(9) b2a2-specific CD4+ T cells. The CD4+ T cells were HLA-DR7 restricted. These results confirm that the generation of donor derived b2a2-specific T cells for clinical use is feasible and warrants clinical testing after stem cell transplantation.

Identification of an antigenic epitope for helper T lymphocytes from carcinoembryonic antigen.

PURPOSE: The product of the carcinoembryonic antigen (CEA) gene is an attractive candidate for T-cell-based immunotherapy because it is frequently expressed in epithelial solid carcinomas. Although many CEA peptide epitopes capable of stimulating CTLs have been identified, no MHC class II-restricted T helper epitope has yet been reported. EXPERIMENTAL DESIGN: The amino acid sequence of CEA was examined for the presence of potential T helper epitopes, and candidate peptides were used to stimulate in vitro T-cell responses. RESULTS: We describe here that using an algorithm to identify promiscuous helper T-cell epitopes, a peptide of CEA occupying residue positions 653 to 667 (CEA(653-667)), was effective in inducing in vitro T helper responses in the context of the HLA-DR4, HLA-DR7, and HLA-DR 9 alleles. Most significantly, some of the peptide-reactive helper T lymphocytes were also capable of recognizing naturally processed antigen in the form of recombinant CEA protein or cell lysates from tumors that express CEA. Interestingly, the newly identified helper T-cell epitope was found to overlap with a previously described HLA-A24-restricted CTL epitope, CEA(652-660), which could facilitate the development of a therapeutic vaccine capable of eliciting both CTL and T helper responses in patients suffering from epithelial carcinomas. CONCLUSION: These results indicate that T helper lymphocytes are capable of recognizing CEA as a tumor antigen and that epitope CEA(653-667) could be used for immunotherapy against tumors expressing CEA.

Revelation of a cryptic major histocompatibility complex class II-restricted tumor epitope in a novel RNA-processing enzyme.

CD4+ T-cell responses against human tumor antigens are a potentially critical component of the antitumor immune response. Molecular methods have been devised for rapidly identifying MHC class II-restricted tumor antigens and elucidating the recognized epitopes. We describe here the identification of neo-poly(A) polymerase (neo-PAP), a novel RNA processing enzyme overexpressed in a variety of human cancers, by screening a melanoma-derived invariant chain fusion cDNA library with tumor-reactive CD4+ T lymphocytes. A cryptic nonmutated HLA-DRbeta1*0701-restricted neo-PAP epitope was processed through the endogenous MHC class II pathway. A unique point mutation effected a nonconservative substitution of a leucine for a proline residue at a structurally important site in neo-PAP that was remote from the recognized peptide, revealing a normally silent epitope for immune recognition. Genetic aberrations such as the described point mutation can have unexpected immunological consequences, in this case leading to immune recognition of a distant normal self epitope.

Identification of HLA DR7-restricted epitopes from human telomerase reverse transcriptase recognized by CD4+ T-helper cells.

CD4+ T cells play critical roles in initiating, regulating, and maintaining antitumor immune responses. One way to improve current tumor vaccines that mainly induce CTLs would be to activate antigen-specific CD4+ T cells that recognize MHC class II restricted tumor associated antigens. Human telomerase reverse transcriptase (hTRT) is preferentially expressed by various tumors and, therefore, could be a universal tumor antigen. In this study, we used a combined approach of using the prediction software TEPITOPE to select class II epitope candidates and in vitro T-cell biological analysis to identify class II-restricted epitope(s) in hTRT. We first identified several HLA-DR7-restricted class-II epitope candidates in hTRT by examining human T-cell responses to synthetic peptides. We then characterized these HLA-DR7-restricted hTRT epitope candidates by establishing and analyzing peptide-specific T-cell clones. It was demonstrated that CD4+ T cells specific for the HLA-DR7-restricted hTRT(672) epitope (RPGLLGASVLGLDDI) can respond to naturally processed hTRT proteins. Furthermore, the hTRT(672)-specific T cells recognized hTRT antigen from various tumors, including prostate cancer, breast cancer, melanoma, and leukemia. Thus, the identification of the naturally processed HLA-DR7-restricted hTRT epitope, together with the previous finding of class I-restricted hTRT epitopes, provide a basis for the combined application of class I- and II-restricted hTRT epitopes to induce potent, long-term CD4+ and CD8+ T-cell responses against a broad spectrum of tumors.

Human lymphocyte antigen DR7 protects against proliferative retinopathy with type II diabetes mellitus.

BACKGROUND: This study was undertaken in order to analyze the genetic incidence of human lymphocyte antigen diabetic retinopathy (HLA-DR) and its influence in proliferative diabetic retinopathy (PDR). METHODS: We designed a case-control study in which 127 mestizo Mexican patients with DM II and diabetic retinopathy were studied. DNA was extracted and HLA-DR regions were amplified using PCR. Alleles were determined by DNA hybridization. Diagnosis was assessed clinically and by fluorescein angiography. Incidence of HLA-DR alleles in patients was compared with an ethnically matched control group of healthy subjects (n = 98). Statistical significance was established with non-parametric tests. RESULTS: Patients with diabetic retinopathy showed less frequency of HLA-D11 compared with the control group (p = 0.043). NPDR patients with 10 or more years of DM II showed an increase of HLA-DR7 (p = 0.01). CONCLUSIONS: Our results suggest that the presence of HLA-DR7 protects against the development of proliferative disease in the diabetic Mexican population.