Question: In the presence of a patient with Crohn's disease who is going to start treatment with biological anti-TNF therapy (antibodies against tumor necrosis factor alpha), which of the following diagnostic tests is not necessary before initiating such therapy? 
 Options:  <1> Evaluation of the immune stage by lymphocyte count. <2> Serology of hepatitis B virus (HBV). <3> Tuberculin test. <4> Chest x-ray. <5> Serology of the human immunodeficiency virus (HIV).
1