Question: A 43-year-old man consulted for diarrheal syndrome, and reported among his background 3 pneumonias in adulthood. Which of the following immunological studies should we request ?: 
 Options:  <1> Serum immunoglobulin count and antibody production capacity test. <2> Phagocytosis test and oxidative metabolism of neutrophils. <3> Apoptosis test (programmed cell death) in the circulating lymphocytes of the patient. <4> Study of the repertoire and clonality of the T lymphocytes (alpha / beta). <5> In this patient, it would not be appropriate to request any immunological study.
1