"B. pertussis" has the ability to inhibit the function of the host's immune system. The toxin, known as pertussis toxin (or PTx), inhibits G protein coupling that regulates an adenylate cyclase-mediated conversion of ATP to cyclic AMP. The end result is that phagocytes convert too much ATP to cAMP, causing disturbances in cellular signaling mechanisms, and preventing phagocytes from correctly responding to the infection. PTx, formerly known as lymphocytosis-promoting factor, causes a decrease in the entry of lymphocytes into lymph nodes, which can lead to a condition known as lymphocytosis, with a complete lymphocyte count of over 4000/μl in adults or over 8000/μl in children. Beside targeting lymphocytes, it limits neutrophil migration to the lungs. It also decreases the function of tissue-resident macrophages, which are responsible for some bacterial clearance.