A 42-year-old man with diabetes presents to the emergency department with fever (39.8°C), hypotension (BP 88/52 mmHg), and altered mental status. Blood cultures grow Gram-negative rods. The structure marked **B** in the diagram contains the endotoxin responsible for his clinical deterioration. Which of the following best explains why initiating antibiotic therapy in this patient may paradoxically worsen his septic shock in the first few hours?