High-scatter T cells: a reliable biomarker for malignant T cells in cutaneous T-cell lymphoma.

In early-stage cutaneous T-cell lymphoma (CTCL), malignant T cells are confined to skin and are difficult to isolate and discriminate from benign reactive cells. We found that T cells from CTCL skin lesions contained a population of large, high-scatter, activated skin homing T cells not observed in other inflammatory skin diseases. High-scatter T (T(HS)) cells were CD4(+) in CD4(+) mycosis fungoides (MF), CD8(+) in CD8(+) MF, and contained only clonal T cells in patients with identifiable malignant Vß clones. T(HS) cells were present in the blood of patients with leukemic CTCL, absent in patients without blood involvement, and contained only clonal malignant T cells. The presence of clonal T(HS) cells correlated with skin disease in patients followed longitudinally. Clonal T(HS) cells underwent apoptosis in patients clearing on extracorporeal photopheresis but persisted in nonresponsive patients. Benign clonal T-cell proliferations mapped to the normal low-scatter T-cell population. Thus, the malignant T cells in both MF and leukemic CTCL can be conclusively identified by a unique scatter profile. This observation will allow selective study of malignant T cells, can be used to discriminate patients with MF from patients with other inflammatory skin diseases, to detect peripheral blood involvement, and to monitor responses to therapy.

Omental Free Flap Coverage for Extracavitary Vascular Bypass Graft Salvage.

BACKGROUND: Prosthetic vascular graft infection is a serious complication associated with significant morbidity and mortality often requiring graft excision and numerous additional operations. Pedicled flaps are often used for the coverage of exposed deep tissue or hardware for graft salvage. In the absence of pedicled options, the properties of omentum make it an excellent choice for free flap tissue coverage, particularly in cases involving implanted prostheses. METHODS: A 63-year-old woman developed a mycotic right subclavian arterial aneurysm requiring ligation and extra-anatomic bypass grafting to restore right-sided intracranial and right upper extremity arterial perfusion. Subsequent wound breakdown and poor healing left the grafts exposed, resulting in contamination. Given the profound risks associated with graft excision in this patient, salvage was attempted with IV antibiotics, serial wound/graft washouts, and graft coverage with an omental free flap. RESULTS: The patient tolerated the procedure well. The remainder of her hospital course was uneventful, and she was discharged home in good clinical condition. She will remain on long-term suppressive antibiotics per Infectious Disease recommendations. CONCLUSIONS: Contemporary literature reporting novel and effective applications of omental free flap coverage is rare. This report demonstrates that omental free flap coverage is safe and can provide healthy tissue to protect implanted grafts and even aid in the salvage of infected extra-anatomic bypass grafts.

Tumor-specific T cells in human Merkel cell carcinomas: a possible role for Tregs and T-cell exhaustion in reducing T-cell responses.

Merkel cell carcinomas (MCCs) are rare but highly malignant skin cancers associated with a recently described polyomavirus. MCC tumors were infiltrated by T cells, including effector, central memory, and regulatory T cells. Infiltrating T cells showed markedly reduced activation as evidenced by reduced expression of CD69 and CD25. Treatment of MCC tumors in vitro with IL-2 and IL-15 led to T-cell activation, proliferation, enhanced cytokine production, and loss of viable tumor cells from cultures. Expanded tumor-infiltrating lymphocytes showed TCR repertoire skewing and upregulation of CD137. MCC tumors implanted into immunodeficient mice failed to grow unless human T cells in the tumor grafts were depleted with denileukin diftitox, suggesting that tumor-specific T cells capable of controlling tumor growth were present in MCC. Both CD4(+) and CD8(+) FOXP3(+) regulatory T cells were frequent in MCC. Fifty percent of nonactivated T cells in MCC-expressed PD-1, a marker of T-cell exhaustion, and PD-L1 and PD-L2 were expressed by a subset of tumor dendritic cells and macrophages. In summary, we observed tumor-specific T cells with suppressed activity in MCC tumors. Agents that stimulate T-cell activity, block regulatory T cell function, or inhibit PD-1 signaling may be effective in the treatment of this highly malignant skin cancer.

Nitric oxide-producing myeloid-derived suppressor cells inhibit vascular E-selectin expression in human squamous cell carcinomas.

Squamous cell carcinomas (SCCs) are sun-induced skin cancers that are particularly numerous and aggressive in immunosuppressed individuals. SCCs evade immune detection at least in part by downregulating E-selectin on tumor vessels, thereby restricting entry of skin-homing T cells into tumors. We find that nitric oxide (NO) potently suppresses E-selectin expression on human endothelial cells and that SCCs are infiltrated by NO-producing iNOS(+) CD11b(+) CD33(+) CD11c(-) HLA-DR(-) myeloid-derived suppressor cells (MDSCs). MDSCs from SCCs produced NO, transforming growth factor-ß (TGF-ß), and arginase, and inhibited endothelial E-selectin expression in vitro. MDSCs from SCCs expressed the chemokine receptor CCR2 (chemokine (C-C motif) receptor 2) and tumors expressed the CCR2 ligand human ß-defensin 3 (HBD3), suggesting that CCR2/HBD3 interactions may contribute to MDSC recruitment to SCCs. Treatment of SCCs in vitro with the inducible nitric oxide synthase (iNOS) inhibitor N(ω)-nitro-L-arginine(L-NNA) induced E-selectin expression at levels comparable to imiquimod-treated SCCs undergoing immunologic destruction. Our results suggest that local production of NO in SCCs may impair vascular E-selectin expression. We show that MDSCs are critical producers of NO in SCCs and that NO inhibition restores vascular E-selectin expression, potentially enhancing T-cell recruitment. The iNOS inhibitors and other therapies that reduce NO production may therefore be effective in the treatment of SCCs and their premalignant precursor lesions, actinic keratoses.

Imiquimod enhances IFN-gamma production and effector function of T cells infiltrating human squamous cell carcinomas of the skin.

Squamous cell carcinomas (SCCs) are sun-induced skin cancers that are particularly numerous and aggressive in patients taking T-cell immunosuppressant medications. Imiquimod is a topical immune response modifier and Toll-like receptor 7 (TLR7) agonist that induces the immunological destruction of SCC and other skin cancers. TLR7 activation by imiquimod has pleiotropic effects on innate immune cells, but its effects on T cells remain largely uncharacterized. Because tumor destruction and formation of immunological memory are ultimately T-cell-mediated effects, we studied the effects of imiquimod therapy on effector T cells infiltrating human SCC. SCC treated with imiquimod before excision contained dense T-cell infiltrates associated with tumor cell apoptosis and histological evidence of tumor regression. Effector T cells from treated SCC produced more IFN-gamma, granzyme, and perforin and less IL-10 and transforming growth factor-beta (TGF-beta) than T cells from untreated tumors. Treatment of normal human skin with imiquimod induced activation of resident T cells and reduced IL-10 production but had no effect on IFN-gamma, perforin, or granzyme, suggesting that these latter effects arise from the recruitment of distinct populations of T cells into tumors. Thus, imiquimod stimulates tumor destruction by recruiting cutaneous effector T cells from blood and by inhibiting tonic anti-inflammatory signals within the tumor.