After breaking up with his longtime girlfriend, eric came down with a severe respiratory infection. he might have experienced a milder form of the infection, if not for his breakup prompting a decrease in his body's release of

Lymphocytes.

Explanation:

Lymphocytes are white bood cells that fight bacterial infections and attack cancer cells and viruses. Eric, after a breakup, surely feels depressed and his immune system is being undermined. Therefore, the lymphocytes aren't able to attack the infection as they are supposed to causing, unfortunately, a severe respiratory infection.

okay what's the question?