Monoclonal antibodies specific to human Δ42PD1: A novel immunoregulator potentially involved in HIV-1 and tumor pathogenesis

Abstract

(2015) Monoclonal antibodies specific to human ∆42PD1: A novel immunoregulator potentially involved in HIV-1 and tumor pathogenesis, mAbs, 7:3, 620-629, DOI: 10.1080DOI: 10. /19420862.2015 To link to this article: https://doi.org/10. 1080/19420862.2015 We recently reported the identification of D42PD1, a novel alternatively spliced isoform of human PD1 that induces the production of pro-inflammatory cytokines from human peripheral blood mononuclear cells and enhances HIVspecific CD8C T cell immunity in mice when engineered in a fusion DNA vaccine. The detailed functional study of D42PD1, however, has been hampered due to the lack of a specific monoclonal antibody (mAb). In this study, we generated 2 high-affinity mAbs, clones CH34 (IgG2b) and CH101 (IgG1), from D42PD1-immunized mice. They recognize distinct domains of D42PD1 as determined by a yeast surface-displaying assay and ELISA. Moreover, they recognize native D42PD1 specifically, but not PD1, on cell surfaces by both flow cytometry and immunohistochemical assays. D42PD1 appeared to be expressed constitutively on healthy human CD14 C monocytes, but its level of expression was down-regulated significantly during chronic HIV-1 infection. Since the level of D42PD1 expression on CD14C monocytes was negatively correlated with the CD4 count of untreated patients in a cross-sectional study, D42PD1 may play a role in HIV-1 pathogenesis. Lastly, when examining D42PD1 expression in human esophageal squamous-cell carcinoma tissues, we found high-level expression of D42PD1 on a subset of tumor-infiltrating T cells. Our study, therefore, resulted in 2 D42PD1-specific mAbs that can be used to further investigate D42PD1, a novel immune regulatory protein implicated in HIV-1 and tumor pathogenesis as well as other immune diseases.

Anti–spike IgG causes severe acute lung injury by skewing macrophage responses during acute SARS-CoV infection

“…Monocyte isolation, differentiation, and polarization of macrophages. Monocytes were purified from peripheral blood mononuclear cells obtained from blood buffy coats (provided by Red Cross, Hong Kong, China) or monkey peripheral blood, as we previously described (52). Monkey peripheral blood was obtained in heparinized vacutainer collection tubes from healthy female rhesus monkeys.…”

Isoformic PD-1-mediated immunosuppression underlies resistance to PD-1 blockade in hepatocellular carcinoma patients

“…These findings indicated that to improve the efficacy of ICB, targeting combinational mechanisms underlying HCC resistance to checkpoint inhibitors is essential for precision treatment. Notably, because Δ42PD-1 cross-reacts neither with PD-1 ligands nor with PD-1 antibodies,17 18 Δ42PD-1 confers a previously unrecognised mechanism of HCC resistance to ICB. We now provide evidence that PD-1 ICB even enhances Δ42PD-1 expression in T cells, which sustains tumourigenicity and likely accounts for one type of the acquired resistance to ICB in HCC patients.…”

“…We previously reported that ∆42PD-1 contains an in-frame deletion of 14-amino acids within the exon 2 of PD-1 and does not interact with PD-L1/L2 17. Furthermore, while most commercially available anti-PD-1 monoclonal antibodies (mAbs) do not recognise ∆42PD-1, two ∆42PD-1-specific mAbs, namely CH101 and CH34, also do not cross-react with PD-1 18. These findings implicated that ICB targeting at PD-1 and PD-L1 will unlikely be useful for treating ∆42PD-1-mediated disease.…”

A Δ42PD1 fusion-expressing DNA vaccine elicits enhanced adaptive immune response to HIV-1: the key role of TLR4

“…Six to eight weeks old female BALB/c mice (Guangdong Medical Laboratory Animal Center) and TLR4 knockout C57BL/6 mice generated using CRISPR/Cas9 technique (Cyagen Biosciences) were bred under standard pathogen-free conditions. For DNA vaccination, each mouse was immunized with 20 μg of endotoxin-free DNA vaccines or pVAX1 vector twice at four-week intervals intramuscularly plus electroporation as we described previously [ 13 ]. Two weeks after the last immunization, mice were euthanized for immunogenicity analysis.…”