CD57 ratio as a convenient and useful immunological and prognostic parameter for stage IV carcinoma

Cluster of differentiation (CD)8+CD57+ T cells are derived through the CD8+ T cell-differentiation signaling pathway from early differentiated CD27+CD8+CD57-T cells (early-CD8+ T cells) to terminal-differentiated CD27-CD8+CD57+ T cells (terminal-CD8+ T cells) via intermediate-differentiated CD27+CD8+CD57+ T cells (intermediate-CD8+ T cells). The increase of CD8+CD57+ T cells in the peripheral blood of patients with cancer has been associated with prognosis, which suggests their suitability as a candidate immunological marker. The present study investigated the association of these CD57-related CD8+ T cell populations in the peripheral blood of 100 Stage IV cancer patients with progression-free survival (PFS), using a Cox regression model. Univariate analysis indicated that early- and intermediate-CD8+ T cells were associated with shorter PFS, whereas terminal-CD8+ T cells were associated with longer PFS. A strong inverse correlation was observed between early- and terminal-CD8+ T cells, and multivariate analysis demonstrated that the CD57 ratio (terminal-CD8+ T cells/early-CD8+ T cells) was a more significant independent prognostic factor compared with early- or terminal-CD8+ T cells. Patients with a higher CD57 ratio had a significantly longer PFS compared with those with a lower CD57 ratio, in whom terminal-CD8+ T cells were supposed to be predominant. Conversely, results indicated inhibition of the CD8+ T cell differentiation signaling pathway in patients with a low CD57 ratio, which lead to a predominance of early-CD8+ T cells, a characteristic of immunosuppressive cells. The present findings suggested that the CD57 ratio appears to be a powerful immunological prognostic parameter obtained from the peripheral blood, precisely reflecting the state of CD8+ T cell-differentiation.