Table of Other Immunodeficiencies

(M2.RH.15.4678) A 3-year-old male is brought to the pediatrician for a check-up. The patient has a history of recurrent ear infections and several episodes of pneumonia. His mother reports the presence of scaly skin lesions on the face and in the antecubital and popliteal fossa since the patient was 2 months old. Physical examination also reveals bruising of the lower extremities and petechiae distributed evenly over the boy's entire body. A complete blood count reveals normal values except for a decreased platelet count of 45,000/mL. Which of the following findings would be expected on follow-up laboratory work-up of this patient's condition?