Autoimmune response in lung cancer patients with neurological paraneoplastic syndromes

The aim of this study was to evaluate granzyme B, perforin and FasL expression in peripheral blood mononuclear cells (PBMCs) in lung cancer patients and in paraneoplastic neurological syndromes (PNS).

Cellular immune response is activated as part of anti-tumour reaction of the malignancy-bearing host. Paraneoplastic neurological syndromes (PNS) are defined as indirect effects of cancer on the nervous system and are considered immune-mediated. Such stimulation of the immune system may limit the aggressiveness of cancer and the development of metastasis, and thereby improve survival. Granzyme B and perforin pathway, and Fas ligand (FasL) - Fas receptor interaction play an important role in cytotoxic response.

Fifty-two patients were included in the study: 28 subjects with PNS and 24 subjects with lung cancer. PNS cases were diagnosed according to the Graus criteria. The presence of onconeural antibodies (anti-Hu/anti-Ri/anti-Yo/anti-Ma/Ta/anti-CV2/anti-amphiphysin/anti-myelin/anti-neuroendothelium/anti-MAG/anti-GAD) was detected with indirect immunofluorescence and confirmed with Line Blotting. The expression of granzyme B, perforin and FasL was detected in PBMCs with ELISA.

PPBMC-FasL expression was increased in lung cancer compared to other patient groups. The granzyme to FasL ratio was significantly higher in lung cancer patients with peripheral than with central PNS involvement. In a multiple regression model, sex was an independent factor influencing PBMC expression of granzyme and perforin.

FasL expression in PBMCs is up-regulated in lung cancer patients. The interplay between granzyme B and FasL may be involved in the development of PNS at the level of the peripheral and the central nervous systems in different manners. Gender is associated with PBMC expression of granzyme B and perforin in lung cancer patients.

The novel findings that we report broaden the current knowledge on PNS pathomechanism, with aspects that have not been previously explored. Our findings provide a rationale for further exploration of the granzyme B/FasL pathway with regards to its potential diagnostic value. However, our study is preliminary and needs further research, especially in the context of the prognostic value of the proposed markers.