To determine the effect of blocking co-stimulation through CD137, isolated peripheral blood mononuclear cells (PBMC) from COPD patients and healthy controls were stimulated with phytohaemagglutinin (PHA) ± blocking anti-CD137 ± 10-6 M methylprednislone (MP) (±stimulatory anti-CD137 and isotyped matched control antibodies) and cytokine profiles and granzyme B expression by T, NKT-like and NK cells were determined using flow cytometry. The gene discussed is GZMB; the disease is chronic obstructive pulmonary disease.