Patients with RA comorbidity had significant differences in cytokine levels of IFNγ (p = 0.035), GM-CSF (p = 0.047), IL-13 (p = 0.036), IL-21 (p = 0.009), and IL-28A (p = 0.002) (Fig. 5a) compared to PAP lesions from patients with no underlying diseases. The gene discussed is IL21; the disease is rheumatoid arthritis.