Measurement of IL-31 production by CD3⁺ cells from MPD or healthy volunteers. CD3⁺ cells (10⁷/mL) were incubated in serum-free media containing 0.1% BSA with or without phytohemagglutinin (PHA; 2 μg/mL) at 37°C. Media was collected after 72 hours of incubation, and total RNA was extracted from each CD3⁺ cell population (MPD, n = 17; healthy volunteers, n = 6). (A) The levels of IL-31were assayed by ELISA. Each column represents the mean ± SD of the levels of IL-31 in each group of CD3⁺ cells. (B) The IL-31 mRNA expression was quantitated by measuring the threshold cycle. The data were presented as relative rates by comparing with the expression of the reference gene β-actin and were analyzed by 2^−ΔΔCT method.