Comparative analysis of antibodies to SARS-CoV-2 between asymptomatic and convalescent patients.

The SARS-CoV-2 viral pandemic has induced a global health crisis, which requires more in-depth investigation into immunological responses to develop effective treatments and vaccines. To understand protective immunity against COVID-19, we screened over 60,000 asymptomatic individuals in the Southeastern United States for IgG antibody positivity against the viral Spike protein, and approximately 3% were positive. Of these 3%, individuals with the highest anti-S or anti-RBD IgG level showed a strong correlation with inhibition of ACE2 binding and cross-reactivity against non-SARS-CoV-2 coronavirus S-proteins. We also analyzed samples from 94 SARS-CoV-2 patients and compared them with those of asymptomatic individuals. SARS-CoV-2 symptomatic patients had decreased antibody responses, ACE2 binding inhibition, and antibody cross-reactivity. Our study shows that healthy individuals can mount robust immune responses against SARS-CoV-2 without symptoms. Furthermore, IgG antibody responses against S and RBD may correlate with high inhibition of ACE2 binding in individuals tested for SARS-CoV-2 infection or post vaccination.

Vaccination with poly(IC:LC) and peptide-pulsed autologous dendritic cells in patients with pancreatic cancer.

BACKGROUND: Dendritic cells (DCs) enhance the quality of anti-tumor immune response in patients with cancer. Thus, we posit that DC-based immunotherapy, in conjunction with toll-like receptor (TLR)-3 agonist poly-ICLC, is a promising approach for harnessing immunity against metastatic or locally advanced unresectable pancreatic cancer (PC). METHODS: We generated autologous DCs from the peripheral blood of HLA-A2+ patients with PC. DCs were pulsed with three distinct A2-restricted peptides: 1) human telomerase reverse transcriptase (hTERT, TERT572Y), 2) carcinoembryonic antigen (CEA; Cap1-6D), and 3) survivin (SRV.A2). Patients received four intradermal injections of 1 × 107 peptide-pulsed DC vaccines every 2 weeks (Day 0, 14, 28, and 42). Concurrently, patients received intramuscular administration of Poly-ICLC at 30 µg/Kg on vaccination days (i.e., day 0, 14, 28, and 42), as well as on days 3, 17, 21, 31, 37, and 45. Our key objective was to assess safety and feasibility. The effect of DC vaccination on immune response was measured at each DC injection time point by enumerating the phenotype and function of patient T cells. RESULTS: Twelve patients underwent apheresis: nine patients with metastatic disease, and three patients with locally advanced unresectable disease. Vaccines were successfully manufactured from all individuals. We found that this treatment was well-tolerated, with the most common symptoms being fatigue and/or self-limiting flu-like symptoms. Among the eight patients who underwent imaging on day 56, four patients experienced stable disease while four patients had disease progression. The median overall survival was 7.7 months. One patient survived for 28 months post leukapheresis. MHC class I -tetramer analysis before and after vaccination revealed effective generation of antigen-specific T cells in three patients with stable disease. CONCLUSION: Vaccination with peptide-pulsed DCs in combination with poly-ICLC is safe and induces a measurable tumor specific T cell population in patients with advanced PC. TRIAL REGISTRATION: NCT01410968 ; Name of registry: clinicaltrials.gov; Date of registration: 08/04/2011).

Interleukin-12 enhances the function and anti-tumor activity in murine and human CD8(+) T cells.

Mouse CD8(+) T cells conditioned with interleukin (IL)-12 ex vivo mediate the potent regression of established melanoma when transferred into lymphodepleted mice. However, the quantitative and qualitative changes induced by IL-12 in the responding mouse CD8(+) T cells have not been well defined. Moreover, the mechanisms by which IL-12-conditioning impacts human CD8(+) T cells, and how such cells might be expanded prior to infusion into patients is not known. We found that ex vivo IL-12-conditioning of mouse CD8(+) T cells led to a tenfold-100-fold increase in persistence and anti-tumor efficacy upon adoptive transfer into lymphodepleted mice. The enhancing effect of IL-12 was associated with maintenance of functional avidity. Importantly, in the context of ongoing ACT clinical trials, human CD8(+) T cells genetically modified with a tyrosinase-specific T cell receptor (TCR) exhibited significantly enhanced functional activity when conditioned with IL-12 as indicated by heightened granzyme B expression and elevated peptide-specific CD107a degranulation. This effect was sustainable despite the 20 days of in vitro cellular expansion required to expand cells over 1,000-fold allowing adequate cell numbers for administration to cancer patients. Overall, these findings support the efficacy and feasibility of ex vivo IL-12-conditioning of TCR-modified human CD8(+) T cells for adoptive transfer and cancer therapy.

Ex vivo interleukin-12-priming during CD8(+) T cell activation dramatically improves adoptive T cell transfer antitumor efficacy in a lymphodepleted host.

BACKGROUND: Clinical application of adoptive T cell therapy has been hindered by an inability to generate adequate numbers of nontolerized, functionally active, tumor-specific T cells, which can persist in vivo. In order to address this, we evaluated the impact of interleukin (IL)-12 signaling during tumor-specific CD8(+) T cell priming in terms of persistence and antitumor efficacy using an established B16 melanoma tumor adoptive therapy model. STUDY DESIGN: B6 mice were injected subcutaneously with B16 melanoma tumor cells. On day 12 of tumor growth, mice were preconditioned with cyclophosphamide (4mg dose, intraperitoneally), and 1 day later were treated by adoptive transfer of tumor-specific pmel-1 CD8(+) T cells primed ex vivo 3 days earlier with both IL-12 and antigen (hGP100(25-33) peptide) or antigen only. Tumors were measured biweekly, and infused donor T cells were analyzed for persistence, localization to the tumor, phenotype, and effector function. RESULTS: Adoptive transfer of tumor-specific CD8(+) T cells primed with IL-12 was significantly more effective in reducing tumor burden in mice preconditioned with cyclophosphamide compared with transfer of T cells primed without IL-12. This enhanced antitumor response was associated with increased frequencies of infused T cells in the periphery and tumor as well as elevated expression of effector molecules including granzyme B and interferon-γ (IFNγ). CONCLUSIONS: Our findings demonstrate that ex vivo priming of tumor-specific CD8(+) T cells with IL-12 dramatically improves their in vivo persistence and therapeutic ability on transfer to tumor-bearing mice. These findings can be directly applied as novel clinical trial strategies.