A 70-year-old man comes to the physician for a 2-day history of fever and cough. Examination shows dullness to percussion of the right lower lobe. Gram stain of the sputum shows gram-positive diplococci. Leukocyte count is 84,000/μL (14% neutrophils; 83% lymphocytes; 3% monocytes). Which of the following is most important to assess in this patient?
Segmented neutrophil function
CD4+ T-lymphocyte count
Serum IgE concentration
Total T-lymphocyte count
Quantitative immunoglobulins
