Which risk increases as a patient's regulatory T cell count declines following prolonged exposure to a novel viral antigen?

💡 Explanation

A decline in regulatory T cells impairs the immune system's ability to suppress self-reactive lymphocytes, because this failure of self-tolerance leads to an increased risk of autoimmune reactions. Therefore, autoimmunity is more likely, rather than diminished cytotoxic T lymphocyte activity, which would increase infection susceptibility.

• Why does mean arterial pressure (MAP) decrease significantly downstream from an arterial stenosis, even if cardiac output remains relatively constant?
• If a new influenza strain suddenly appears, why does vaccine-induced B-cell affinity maturation lead to cross-protection, even though the vaccine was designed for a different strain?
• A patient experiences an asthma exacerbation characterized by increased airway resistance. Which mechanism explains why inhaled beta-2 agonists rapidly alleviate bronchospasm following mast cell histamine release?
• A patient experiences increasing shortness of breath, normal blood pressure, and pulmonary congestion. What causes this effect when cardiac output falls despite elevated sympathetic activity?
• If a 60-year-old individual experiences increased difficulty reading small print despite using reading glasses, which mechanism explains this phenomenon in terms of lens curvature?
• Why does immune thrombocytopenic purpura (ITP) sometimes persist despite initial treatment with corticosteroids?