Production and characterization of a panel of anti-mouse placenta-specific protein 1 (plac1) monoclonal antibodies.

Placenta-Specific Protein 1 (PLAC1) is essential for normal placental and embryonic development. It is widely expressed in various types of cancer cells. We produced a panel of anti-mouse plac1 monoclonal antibodies (mAbs) with different applications. Two recombinant proteins were produced containing either the extracellular domain (ED) plus tetanus toxin P2, P30, pan-DR epitope (PADRE), and KDEL3 (main plac1) or ED plus KDEL3 (control plac1). Recombinant proteins were used for immunization and screening. Positive clones were selected by ELISA and flow cytometry. Purified mAbs were tested by ELISA, WB, flow cytometry, immunohistochemistry (IHC), and immunofluorescent (IF). A combination of bioinformatics tools was used to predict the target epitope(s) of the mAbs. Eight anti-mouse plac1 mAbs (all IgG1/κ1) were generated, all reacting with high affinity in ELISA. Seven clones recognized plac1 in both reduced and non-reduced Western blots, while one only recognized the non-reduced form. Cross-inhibition ELISA revealed that all mAbs recognized overlapping epitopes with a shared motif except for 5C9. Four clones reacted with the native antigen in flow cytometry, but none were functional in IF or IHC staining. The produced multifunctional mAbs can be used to investigate different aspects of PLAC1 biology in reproduction and cancer.

Discovery of a novel marker for human granulocytes and tissue macrophages: RTL1 revisited.

Here, retrotransposon-like 1 (RTL1) is introduced as a marker for circulating and tissue neutrophils, tissue macrophages, and tumor-associated macrophages (TAM) and neutrophils (TAN). Anti-RTL1 polyclonal and monoclonal antibodies were produced, and their reactivity was examined by Western blotting (WB), ELISA, and immunostaining of human normal and cancer tissues. The reactivity of the anti-RTL1 antibodies with peripheral blood leukocytes and a panel of hematopoietic cell lines was examined. The generated antibodies specifically detected RTL1 in the WB of the placenta and U937 cells. The polyclonal antibody showed excellent reactivity with tissue-resident macrophages, Hofbauer cells, alveolar and splenic macrophages, Kupffer cells, and inflammatory cells in the tonsil, appendix, and gallbladder. In vitro GM-CSF-differentiated macrophages also showed a high level of intracellular RTL1 expression. TAM and TAN also showed excellent reactivity with this antibody. Almost all circulating granulocytes but not lymphocytes or monocytes expressed RTL1 at their surface. Serial sections of the appendix stained with CD15 and RTL1 and placenta stained with CD68 and RTL1 showed a considerable overlap in RTL1 expression in CD15+ granulocytes and CD68+ macrophages. A small percentage of myelomonocytic cell lines was positive for surface RTL1, while promyelocytic, monocytic, megaloblastic, and lymphoblastic cell lines were negative. Endothelial cells of normal and cancer tissues highly expressed RTL1. RTL1 could be considered a new marker for different normal tissue macrophages, TAM, circulating and tissue neutrophils, and TAN.

Serological assay for anti-SARS-CoV-2 antibodies improves sensitivity of diagnosis of COVID-19 patients.

The emergence of SARS-CoV-2, responsible for coronavirus disease-2019 (COVID-19), has become a major global health problem. The molecular testing is the accepted assay in SARS-CoV-2 detection. However, there are several reasons for low sensitivity by RNA detection, causing challenges in SARS-CoV-2 diagnosis. In this study, we aimed to investigate serological patterns of SARS-CoV-2 specific IgM, and IgG in 111 hospitalized, and 34 recovered COVID-19 patients and 311 prepandemic normal serum specimens by ELISA. The validity of the ELISA kits was evaluated using samples from normal and recovered cases. This showed that 98.1%, and 98.4% of prepandemic normal samples were negative for anti-SARS-CoV-2 IgM, and IgG, respectively. Assessment of 34 COVID-19 confirmed recovered patients showed a test sensitivity of 76.5%, and 94.1% for IgM, and IgG, respectively. In COVID-19 hospitalized patients, 42.3%, and 51.4% were positive for IgM and IgG, respectively. Viral RNA was not detectable in 43.3% of the hospitalized patients. Interestingly, combined molecular and serological testing improved the sensitivity of COVID-19 diagnosis to 79.6%. Using PCR with combined IgM/IgG results augmented the patient diagnosis sensitivity to 65.3% and 87.2% in ≤ 7 days, and > 7 days intervals, respectively. Overall, serological tests in combination with PCR can improve the sensitivity of COVID-19 diagnosis.

CAR T cells: Living HIV drugs.

Human immunodeficiency virus type 1 (HIV-1), the virus that causes AIDS (acquired immunodeficiency syndrome), is a major global public health issue. Although the advent of combined antiretroviral therapy (ART) has made significant progress in inhibiting HIV replication in patients, HIV-infected cells remain the principal cellular reservoir of HIV, this allows HIV to rebound immediately upon stopping ART, which is considered the major obstacle to curing HIV infection. Chimeric antigen receptor (CAR) cell therapy has provided new opportunities for HIV treatment. Engineering T cells or hematopoietic stem cells (HSCs) to generate CAR T cells is a rapidly growing approach to develop an efficient immune cell to fight HIV. Herein, we review preclinical and clinical data available for the development of CAR T cells. Further, the advantages and disadvantages of clinical application of anti-HIV CAR T cells will be discussed.

Evaluation of TLR9 expression on PBMCs and CpG ODN-TLR9 ligation on IFN-α production in SLE patients.

CONTEXT: Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by autoreactive antibodies. Recent findings revealed the importance of innate immune responses, especially Toll-like receptors (TLRs) in the pathogenesis of SLE. OBJECTIVE: In this study, the level of TLR9 expression on peripheral blood mononuclear cells (PBMCs) was analyzed. The levels of produced IFN-α were also measured in supernatant of PBMCs from SLE patients and healthy controls after stimulation with CpG ODN2216 which is a plasmocytoid dendritic cell (pDC)-specific TLR9 ligand. MATERIALS AND METHODS: TLR9 expression was analyzed by real-time polymerase chain reaction (PCR) and flow cytometry in 35 SLE patients and 38 healthy controls and IFN-α concentration was measured in supernatants using enzyme-linked immunosorbent assay (ELISA). RESULTS: The results showed that the TLR9 expression in the mRNA and the protein level was significantly higher in PBMCs from SLE patients. However, IFN-α concentration in patients and controls significantly increased in response to CpG stimulation but this increase was significantly higher in healthy controls compared with SLE patients. Our results do not show any association between taking hydroxychloroquine and reduction in IFN-α production in SLE patients. DISCUSSION AND CONCLUSIONS: Regarding the findings of the study, there is the possibility that TLR9 has played a role in SLE pathogenesis, and consequently it implies that TLRs can be considered to be the therapeutic targets for systemic autoimmunity. We may conclude that PBMCs in patients are functionally impaired in response to TLR ligation via innate response stimulating pathogen-associated molecular patterns (PAMPs).

Identification, Isolation, and Functional Assay of Regulatory T Cells.

Two categories of regulatory T cells (Tregs), nTreg and iTreg, play vital roles in orchestrating the integrity of a host in the course of an immune response. Tregs commonly belong to CD4+ CD25+ T cells and they are characterized by a transcription factor - forkhead box P3 (FoxP3). Within the space of the last few years, interests have been drawn to Tregs as a therapeutic tool in several settings like autoimmune disease, transplantation, and tumor disorders. As a consequence, to assess the functional properties of Tregs, namely through their ability to suppress other cells, cytokine expression, and proliferation in a variety of conditions, it is mandatory to gain better approaches to this end. This would be beneficial in designing better-than-ever therapeutic methods with regard to Tregs properties. Gaining better insights into the underlying mechanisms of immune regulation, by means of straightforward and less time-consuming techniques, will hopefully permit the therapeutic application of these cells in the control of human disorders. This review aims at going through the basic methods for Treg isolation as well the efficiency of the commonly exerted in vitro assays of Tregs-mediated immune suppression.

Potent anti-tumor immune response and tumor growth inhibition induced by HER2 subdomain fusion protein in a mouse tumor model.

PURPOSE: Several approaches have so far been employed to establish anti-tumor immunity by targeting HER2 protein. Active immunization with recombinant HER2 subdomains has previously been demonstrated to induce potent immune response and tumor growth inhibition. In the present study, we investigated the immunogenicity and tumor inhibitory effect of a fusion protein consisting of human HER2 extracellular subdomain (ECD-DI + II) together with T-helper cell epitopes of Tetanus toxin (p2 and p30). METHODS: BALB/c mice were immunized with two recombinant proteins (DI + II and p2p30-DI + II) emulsified in 4 different adjuvants. Anti-DI + II antibody response, cytokine profile, frequency of splenic CD25+FOXP3+ regulatory T cells (Tregs) and CD8+CD107a+ cytotoxic T lymphocytes (CTLs) were assessed in the immunized mice. To assess the anti-tumor effect, the immunized mice were subcutaneously challenged with HER2-overexpressing tumor cells and the tumor growth was determined. RESULTS: Both recombinant proteins were able to induce comparable levels of ECD-DI + II-specific antibodies. Immunization with p2p30-DI + II resulted in a significant increase in the level of Interferon-gamma (IFN-γ) secretion compared to DI + II protein and significantly higher frequency of CTLs and lower frequency of Tregs. The number of mice that remained tumor-free until day 120 was significantly higher in p2p30-DI + II vaccinated groups. CONCLUSIONS: Our data suggest that the p2p30-DI + II fusion protein together with CpG adjuvant induces more potent anti-tumor immune responses in a mouse tumor model. Accordingly, this formulation might be considered as a potential immunotherapeutic approach in HER2+ cancers.

Prevalence of Anti-SARS-CoV-2 Specific Antibodies in Health-Care Workers Compared to General Population during an Early Phase of the Pandemic, Tehran-Iran.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapidly transmits in general population, mainly between health-care workers (HCWs) who are in close contact with patients. OBJECTIVE: To study the seropositivity of HCWs as a high-risk group compared to general population. METHODS: 72 samples were obtained from HCWs working in Masih Daneshvari hospital as one of the main COVID-19 admission centers in Tehran, during April 4 to 6, 2020. Also we collected 2021 blood samples from general population. The SARS-CoV-2 specific IgM, and IgG antibodies in the collected serum specimens were measured by commercial ELISA kits. RESULTS: Based on the clinical manifestations, 25.0%, 47.2%, and 27.8% of HCWs were categorized as symptomatic with typical symptoms, symptomatic with atypical symptoms, and asymptomatic, respectively. Symptomatic individuals with typical and atypical symptoms were 63.2% and 36.8% positive in RT-PCR test, respectively. Anti-SARS-CoV-2 IgM and IgG antibodies were detected in 15.3% and 27.8% of HCWs samples, respectively. Antibody testing in the general population indicated that SARS-CoV-2 specific IgM and IgG were found in (162/2021) 8%, and (290/2021) 14.4%, respectively. The frequency of positive cases of IgM and IgG were significantly increased in HCWs compared to general population (p= 0.028 for IgM and p= 0.002 for IgG). CONCLUSION: The frequency of SARS-CoV-2 specific antibodies in HCWs was higher than general population indicating a higher viral transmission via close exposure with COVID-19 patients.

Induction of Systemic Lupus Erythematosus-like Syndrome in BALB/c Mice Leads to Disturbance in Splenic T Cell Subpopulations.

Mechanisms underlying the systemic lupus erythematosus (SLE) have not yet been elucidated. In this study, we evaluated the balance of T cell subsets in BALB/c mice model of SLE induced; using Con A and polyamines as DNA immunogenicity modifiers. BALB/c mice were immunized subcutaneously with 50 µg extracted DNA from cells cultured in different conditions: splenocytes+ polyamines (group P), splenocytes+ Con A (group A), splenocytes+ polyamines+ Con A (group PA) and splenocytes only (control). Anti-double-stranded DNA -(ds-DNA) antibodies, proteinuria, and antinuclear autoantibodies were assessed by enzyme-linked immunosorbent assay, Bradford method, and immunofluorescence respectively. Transcription factors of different T helper subsets were examined by real-time polymerase chain reaction. The serum level of the anti-dsDNA antibody in group PA was higher than that in the other groups (p>0.05). Antinuclear antibody (ANA) titer increased in groups A and PA. Proteinuria level in group PA was significantly higher than that in the control group (p<0.001). Expression of Foxp3 was decreased in group A (p=0.001). Additionally, the ratios of T-bet/GATA3 and T-bet/Foxp3 were also increased in group A. (p>0.05). Our results revealed an increased ratio of Th1 to Th2 and decreased expression of Foxp3 in group A, but group PA manifested more obvious signs of the disease. These results suggest that other mechanisms rather than disturbance in T cells' balance may involve the development of disease symptoms.

Evaluation of PBMC Distribution and TLR9 Expression in Patients with Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease which results in damage to various organs. Some animal studies have revealed that activation of Toll-like receptors (TLRs) is important in the pathogenesis of SLE. In the present study, the percentage of different immune cell subsets in 35 SLE patients and 38 control subjects was analyzed by flow cytometry. We also assessed the expression of TLR9 in the population of peripheral blood mononuclear cells (PBMCs) including T lymphocytes (CD4+ and CD8+), B lymphocytes (CD19+), NK cells (CD56+) and monocytes (CD14+) in SLE patients and healthy controls. The results showed that the percentage of CD8+ T lymphocytes and CD14+ monocytes were significantly higher (p˂0.001) in the SLE patients than the healthy control subjects. Moreover, the percentage of CD56+ NK cells were significantly lower in the SLE patients than the healthy control subjects (p=0.001). The findings indicated that the expression of TLR9 was significantly higher in CD4+ and CD8+ T lymphocytes and CD19+ B lymphocytes of SLE patients than in control subjects (all p˂0.05). The difference in TLR9 expression are involved in pathogenesis of the SLE, hence it can be used as an indicator for SLE diagnosis.