Post-splenectomy Medical Question:
A 38 year old male is brought to the ED with because of altered mental status. His wife reports that he has had fever and cough for the past 2 days. His past medical history is significant for splenectomy two years ago due to abdominal trauma and left sided nephrectomy. On physical examination his temperature is 102.2 F, blood pressure 85/50 mmHg, pulse is 111/min, and his respirations are 34/min. Gram-positive cocci are cultured from his blood. Which of the following is most likely impaired in this patient?
A) Intracellular killing
B) Number of circulating lymphocytes
E) Cell-mediated immunity
This patient presents with overwhelming post-splenectomy sepsis. Normally blood-borne antigens enter the spleen via the splenic artery and are phagocytosed by dendritic cells in the white pulp. These dendritic cells then present antigens in association with MHC II to T-helper cells, activating them. Activated T-helper cells then migrate to the marginal zone of the spleen where they come into contact with B-cells in primary follicles. B-cell activation causes secondary follicles and plasma cell-rich germinal cells to form. Antibodies produced by germinal center plasma cells enter the systemic circulation, bind their specific antigen, and facilitate phagocytosis of pathogenic organisms by Opsonization. Asplenic patient are less able to mouth this sort of antigen-specific antibody response and are therefore at high risk of overwhelming infection by encapsulated organisms like S. pneumoniae, N. meningitidis and H. influenzae