2. Compare and contrast the mechanisms of humoral and cell-mediated immunity, and explain how both immune systems combat infection (6 points). Give examples of diseases resulting from immune system dysfunction (6 points). 比較體液免疫和細胞免疫的機制，並說明兩種免疫系統如何抵抗感染（6 分）。請舉例說明免疫系統失調所導致的疾病（6 分）。