Alteration of signal-transducing molecules and phenotypical characteristics in peripheral blood lymphocytes from gastric carcinoma patients

The mechanisms underlying the impaired immune response frequently observed in cancer patients are not fully understood. Alteration of T-cell-associated signal transduction molecules has recently been implicated in immune suppression in tumor-bearing hosts. Furthermore, T cells from tumor-bearing host, irrespective of the presence of the zeta-chain, showed a lack of proliferative activity and cytotoxic function. In the present study, we investigated the expression of the zeta-chain molecule and the p56(lck) and p59(fyn) protein tyrosine kinase (PTK) levels in peripheral blood T lymphocytes (T-PBL) from patients with advanced gastric carcinomas; for this, flow cytometric analysis and immunoblotting, respectively, were used. We also compared the results of flow cytometric analysis of PBL between stomach cancer patients and normal healthy volunteers. In T-PBL from 22 tumor-bearing hosts, significantly reduced zeta-chain expression (16/22, 73%) was observed. Moreover, the expression level of p56(lck) in T-PBL from patients was significantly lower than that of p59(fyn). Flow cytometric analysis of T-PBL indicated a markedly increased CD8+28- cell population in T-PBL from 19 tumor-bearing hosts.