Regulatory T cells mediate specific suppression by depleting peptide-MHC class II from dendritic cells.

Regulatory T cells (Treg cells) can activate multiple suppressive mechanisms in vitro after activation via the T cell antigen receptor, resulting in antigen-independent suppression. However, it remains unclear whether similar pathways operate in vivo. Here we found that antigen-specific Treg cells activated by dendritic cells (DCs) pulsed with two antigens suppressed conventional naive T cells (Tnaive cells) specific for both cognate antigens and non-cognate antigens in vitro but suppressed only Tnaive cells specific for cognate antigen in vivo. Antigen-specific Treg cells formed strong interactions with DCs, resulting in selective inhibition of the binding of Tnaive cells to cognate antigen yet allowing bystander Tnaive cell access. Strong binding resulted in the removal of the complex of cognate peptide and major histocompatibility complex class II (pMHCII) from the DC surface, reducing the capacity of DCs to present antigen. The enhanced binding of Treg cells to DCs, coupled with their capacity to deplete pMHCII, represents a novel pathway for Treg cell-mediated suppression and may be a mechanism by which Treg cells maintain immune homeostasis.

Talimogene Laherparepvec (TVEC) for the Treatment of Advanced Melanoma: A Single-Institution Experience.

BACKGROUND: Talimogene laherparepvec (TVEC) is an oncolytic herpes virus used as intralesional therapy for patients with unresectable stage IIIB through IV melanoma. We reviewed the standard of care treatment of TVEC at a single institution. METHODS: All patients treated with TVEC for advanced melanoma were retrospectively evaluated from 2015 to 2018. Patient demographics, clinicopathologic characteristics, treatment response, and toxicity were reviewed. RESULTS: Twenty-seven patients underwent therapy with TVEC. Median age was 75 years, and 63% of patients were female. Seventeen (63.0%) patients underwent injections on the lower extremity, four (14.8%) on the upper extremity, four (14.8%) on the head and neck, and two (7.4%) on the trunk. Median number of injections was five. Median follow-up was 8.6 months. Of the 27 patients, 23 patients met the criteria for response analysis with at least 8 weeks follow-up. Ten (43.5%) patients experienced a complete response (CR), three (13.1%) experienced a partial response (PR), and five (21.7%) had stable disease (SD) for an overall response rate of 56.5% (CR + PR) and a disease control rate of 78.3% (CR + PR + SD). Adverse events were mostly limited to mild constitutional symptoms within 48 h of injection. Two patients developed cellulitis treated with oral antibiotics, and one patient underwent excision of a lesion for ulceration and bleeding during therapy. DISCUSSION: TVEC is an effective and well-tolerated intralesional therapy for patients with unresectable stage IIIB through IV melanoma. A CR was achieved in almost half of patients treated. Disease control is seen in the vast majority.

Resection Margins in Merkel Cell Carcinoma: Is a 1-cm Margin Wide Enough?

BACKGROUND: Guidelines regarding specific resection margins for primary Merkel cell carcinoma (MCC) are not well established. The current National Comprehensive Cancer Network (NCCN) guidelines recommend 1- to 2-cm resection margins. This study aimed to determine the impact of margin width on local recurrence (LR), disease-specific survival (DSS), overall survival (OS), and type of wound closure. METHODS: All patients who underwent resection of primary MCC at a single institution from 2000 to 2015 were reviewed. Patient demographics, clinicopathologic characteristics, treatments, and outcomes were reviewed. RESULTS: A total of 240 patients underwent resection of primary MCC with resection margin width identified in the operative report. The median age was 76 years, and 65.8% of the patients were men. Of the 240 patients, 85 (35.4%) had head and neck primaries, 140 (58.3%) had extremity primaries, and 15 (6.3%) had trunk primaries. In terms of margins, 69 patients (28.8%) had a margin of 1 cm, 36 patients (15%) had a margin of 1.1-1.9 cm, and 135 patients (56.2%) had a margin of 2 cm or more. The median follow-up period was 21 months. The LR rate was 2.9% for a margin of 1 cm, 2.8% for a margin of 1.1-1.9 cm, and 5.2% for a margin of 2 cm or more (p = 0.80). The 5-year OS was 63.6% for a margin of 1 cm, 59.7% for a margin of 1.1-1.9, and 70.7% for a margin of 2 cm or more (p = 0.66). The 5-year DSS was 80.3% for a margin of 1 cm, 66.2% for a margin of 1.1-1.9 cm, and 91.8% for a margin of 2 cm or more (p = 0.28). For wound closure, 43.5, 50, and 65.9% of the patients respectively required a flap or graft with a margin of 1, 1.1-1.9, and 2 cm or more (p = 0.006). CONCLUSIONS: A 1-cm resection margins did not increase the risk of LR. Margin width did not make a significant difference in DSS or OS. Larger resection margins increase the need for a graft or flap closure.

A Simple, Versatile Antibody-Based Barcoding Method for Flow Cytometry.

Barcoding of biological samples is a commonly used strategy to mark or identify individuals within a complex mixture. However, cell barcoding has not yet found wide use in flow cytometry that would benefit greatly from the ability to analyze pooled experimental samples simultaneously. This is due, in part, to technical and practical limitations of current fluorescent dye-based methods. In this study, we describe a simple, versatile barcoding strategy that relies on combinations of a single Ab conjugated to different fluorochromes and thus in principle can be integrated into any flow cytometry application. To demonstrate the efficacy of the approach, we describe the results of a variety of experiments using live cells as well as fixed and permeabilized cells. The results of these studies show that Ab-based barcoding provides a simple, practical method for identifying cells from individual samples pooled for analysis by flow cytometry that has broad applications in immunological research.

A rare concurrence of Muir-Torre-associated sebaceous carcinoma in the setting of a lipedematous scalp.

Muir-Torre syndrome (MTS) a genetic disorder characterized by predisposition to cutaneous neoplasms. Lipedematous scalp is characterized by the presentation of a thick, sponge-like scalp due to the altered and increased deposition of adipose tissue. We present a case of Muir-Torre-associated sebaceous carcinoma of the scalp consistent with a lipedematous scalp.

Ex-vivo iTreg differentiation revisited: Convenient alternatives to existing strategies.

Ex-vivo differentiation of regulatory T cells (Tregs) from naïve CD4+ T-cells has been widely used in immunological research. Isolation of a highly pure naïve T cell population is the key factor that determines the efficiency of subsequent Treg differentiation. Currently, this step relies mostly on FACS sorting, which is often costly, time consuming, and inconvenient. Alternatively, magnetic separation of T-cells can be performed; yet, available protocols fail to reach sort level purity and consequently result in low Treg differentiation efficiency. Here, we present the results of a comprehensive side-by-side comparison of various magnetic separation strategies and FACS sorting in multiple levels. Additionally, we propose a novel optimized custom made magnetic separation protocol, which not only yields sort level purity and Treg differentiation but also lowers the reagent costs up to 75% compared to the commercially available purification kits. The highly pure naïve CD4+ T-cell population obtained by this versatile method can also be used for differentiation of other T-cell subsets; therefore this protocol may have broad applications in T-cell research.