IL-4 and IL-13 mRNA expression in PMBL. (A) IL-4 (▴) and IL-13 (▵) transcript levels were measured by quantitative RT-PCR in reactive lymph nodes (n = 4), PMBL (n = 8), and DLBCL (n = 8) samples as reported in “Materials and methods.” Results are expressed as IL-4/IL-13 copy number per 10⁶ copies of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Bars indicate the median and interquartile values. (B) IL-4 and IL-13 transcript levels were measured by quantitative RT-PCR as in panel A in various lymphoma-derived B-cell lines.