title: Evidence of Th2 polarization of the sentinel lymph node (SLN) in melanoma.
abstract: Melanoma has a propensity for lymphatogenous metastasis. Improved understanding of the sentinel lymph node (SLN) immunological environment may improve outcomes. The immune phenotype of fresh melanoma SLNs (n= 13) were compared to fresh control lymph nodes (n= 13) using flow cytometry. RNA was isolated from CD4+T cells of the SLN and control lymph node and assessed for Th1/Th2 gene expression pathways using qRT-PCR. In addition, VEGF expression was compared between primary melanoma (n= 6) and benign nevi (n= 6) using immunohistochemistry. Melanoma SLNs had fewer CD8+T cells compared to controls (9.2% vs. 19.5%,p= 0.0005). The CD8+T cells within the SLN appeared to have an exhausted phenotype demonstrated by increased PD-1 mRNA expression (2.2% vs. 0.8%,p= 0.004) and a five-fold increase in CTLA-4 mRNA expression. The SLN also contained an increased number of CD14 (22.7% vs. 7.7%,p= 0.009) and CD68 (9.3% vs. 2.7%,p= 0.001) macrophages, and CD20 B cells (31.1% vs. 20.7%,p= 0.008), suggesting chronic inflammation. RT-PCR demonstrated a significant Th2 bias within the SLN.In vitrostudies demonstrated a similar Th2 polarization with VEGF treatment of control lymph nodes. The primary melanoma demonstrated strong VEGF expression and an increase in VEGFR1 within the SLN. Melanoma is associated with Th2-mediated "chronic inflammation," fewer cytotoxic T cells, and an exhausted T cell phenotype within the SLN combined with VEGF overproduction by the primary melanoma. These immunologic changes precede nodal metastasis and suggests consideration of VEGF inhibitors in future immunotherapy studies.
authors.affiliation: Department of Surgery; Mayo Clinic ; Rochester MN USA.
authors.forename: Travis E
authors.initials: TE
authors.lastname: Grotz
authors.affiliation: Department of Surgery; Mayo Clinic ; Rochester MN USA.
authors.forename: James W
authors.initials: JW
authors.lastname: Jakub
authors.affiliation: Department of Oncology ; Rochester; MN USA.
authors.forename: Aaron S
authors.initials: AS
authors.lastname: Mansfield
authors.affiliation: Mayo Clinic Graduate School of Medicine; Mayo Clinic ; Rochester MN USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Goldenstein
authors.affiliation: Mayo Clinic Graduate School of Medicine; Mayo Clinic ; Rochester MN USA.
authors.forename: Elizabeth Ann L
authors.initials: EA
authors.lastname: Enninga
authors.affiliation: Department of Oncology ; Rochester; MN USA.
authors.forename: Wendy K
authors.initials: WK
authors.lastname: Nevala
authors.affiliation: Department of Health Sciences Research at the Mayo Clinic ; Rochester MN USA.
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Leontovich
authors.affiliation: Mayo Clinic Graduate School of Medicine; Mayo Clinic ; Rochester MN USA.
authors.forename: Svetomir N
authors.initials: SN
authors.lastname: Markovic
keywords:  CD4 T cells; CD8 T cells; Th2 polarization; VEGF; immunotherapy; inflammation; lymphocytes; melanoma; sentinel lymph node