Higher prevalence of LAP+ (Latency TGFβ-Associated Peptide) T cells at the tissue level in patients with early gastric cancer

Abstract

The presence of cells with regulatory functions in patients with cancer is one of the mechanisms whereby the immune system cannot confront tumor growth. We sought to determine the prevalence of immunoregulatory Tcell subpopulations, expressing the latency TGFβ-associated peptide (LAP), in patients with gastric adenocarcinoma.
T cells were enriched from blood or gastric tissue (tumoral, TT or tumor-free, TF) samples from 22 patients, 6 with early (EGC) and 16 with advanced gastric cancer (AGC). CD4, CD8, LAP, FoxP3 and IFN-γ were measured by cytometry.
CD8 + LAP + cells were increased at tumoral sites, especially in early stages of the disease, as compared to tumor-free explants (EGC 5.28 % [4.67–6.64]*; AGC 2.90 % [1.37–4.44]; TF 3.14 % [2.33–4.16]; *p < 0.05 vs TF). Likewise, the LAP+/CD8 + LAP- ratio is increased in gastric samples from patients with early disease (EGC 0.38 [0.30–0.45]*, AGC 0.12 [0.07–0.14]; TF 0.12 [0.09–0.31]; *p < 0.05 vs AGC). Disease progression is accompanied by decreased LAP membrane expression and, probably, increased LAP secretion, therefore limiting the response to the tumor.