HRH1 and ovarian endometriosis: Immunostaining also revealed abundant CD45-positive cells and robust colocalization between all histamine receptors and CD45 in ovarian endometriosis (HRH1: 0.58, 0.29–1.05; HRH2: 0.39, 0.06–1.23; HRH3: 0.62, 0.18–1.16; HRH4: 1.24, 0.60–1.92; all p < 0.0001; Figure 4I–L), compared with minimal or absent colocalization in controls.