An 18-year-old college student is brought to the emergency department with sudden-onset high fever, severe headache, and nuchal rigidity. Lumbar puncture yields turbid cerebrospinal fluid with neutrophilic pleocytosis. Gram stain demonstrates gram-negative diplococci, and culture confirms Neisseria meningitidis serogroup B. Which of the following best explains how the polysaccharide capsule of this organism promotes immune evasion?