We found that the number of macrophage clusters expressing CD68, a macrophage-specific marker, significantly increased in the early-progressed BPH tissues (mean ± standard error of the mean (SEM): 7.9 ± 4.5), compared to those in the age-matched prostate (1.8 ± 1.4) and elderly BPH (2.9 ± 2.6) tissues (both P < 0.001; Fig. 2a, b). Here, CD68 is linked to benign prostatic hyperplasia.