We next investigated potential differences in the activation of macrophages in the presence or absence of specific antibodies following challenge infection with Hp. As RNA samples from granulomas were not of sufficient quality for microarray analysis, we performed in vitro experiments with bone marrow-derived macrophages (BMMac) that we incubated with Hp immune serum (1∶50, v∶v) and infective Hp L3 larvae (500 larvae/106 cells). This evidence concerns the gene HP and infection.