Granzyme B in peripheral blood mononuclear cells as a measure of cell-mediated immune response in paraneoplastic neurological syndromes and malignancy.

Background Paraneoplastic neurological syndromes (PNS) may coexist with ovarian or lung cancers. Some tumors coexisting with PNS are smaller and have a better prognosis than tumors without PNS. PNS may constitute an opportunity to observe a natural immune antitumor response. We aimed to investigate a cytotoxic immune response by measuring granzyme B (GrB) in peripheral blood mononuclear cells (PBMC) in patients affected with ovarian or lung malignancy, with and without accompanying PNS. Methods We enrolled patients with: nonmalignant lesions (n = 21), ovarian cancer (n = 19), lung cancer (n = 57), and PNS (n = 30). PBMC were isolated by density gradient centrifugation with Ficoll-Paque. We evaluated the expression of GrB in PBMC lysates by ELISA and normalized to protein content as measured by the Lowry method. Results GrB levels in PBMC in the group with malignant tumors-median 1650 pg/mg protein (interquartile range 663-3260 pg/mg) and in patients with PNS-median 1890 pg/mg protein (range 1290-2640 pg/mg) was lower than in control group with nonmalignant lesions-median 5240 pg/mg protein (range 2160-7440 pg/mg), p = 0.0003 and p = 0.0038, respectively. The differences in GrB levels in PBMC between these groups were independent of epidemiological factors-age, sex, body mass index (BMI), and the number of immune cells, as confirmed by multiple regression analysis. Within the group of patients with malignancy and PNS, GrB levels in PBMC were elevated if onconeural antibodies were detected (2610; 2390-3700 pg/mg protein) as compared to patients without antibodies (1680; 970-1880 pg/mg protein, p = 0.035). GrB in PBMC was higher if the malignancy was diagnosed at the low (3060; 2120-5220 pg/mg protein) as compared to the high stage (1330; 348-2140, p = 0.00048). In patients with lung cancer, the expression of GrB in PBMC was lower (1430; 635-2660 pg/mg protein) than in the group with ovarian cancer (2580; 1730-3730, p = 0.02). Conclusion The cytotoxic response measured in peripheral blood by GrB in PBMC is impaired both in the course of malignancy and PNS. Levels of GrB in PBMC were higher if onconeural antibodies were detected. Tracking reactive immune responses, such as GrB in PBMC may have diagnostic and monitoring value in malignancy and PNS.