###Rationale: This is a case of Infectious mononucleosis. So, there are no B-cells in X-linked agammaglobulinemia to be affected. 1st image shows tonsillitis with membrane formation Peripheral blood film shows atypical lymphocytes or Downey cells are lymphocytes that become large as a result of antigen stimulation. B cells are the main reservoir of infection. An EBV envelope glycoprotein binds CD21 (CR2), the receptor for the C3d component of complement, which is present on B cells.

###Answer: OPTION A IS CORRECT.
###Question: A 3-year-old child presented with fatigue, malaise, fever, sore throat, headache, nausea, abdominal pain and myalgia. O/E Generalized lymphadenopathy Hepatosplenomegaly, Tonsillar enlargement Palatal petechiae Rashes and edema of the eyelids. Some weird cells were observed in the peripheral blood. A specific serological test was performed Which of the following receptor is involved in the pathogenesis of the above disease: -
###Options:
A. CD21
B. CD20
C. CD19
D. CD117
