IgM

例句：

1. 1. The study found that IgM antibodies were present in the patient's blood.
   研究发现患者血液中存在IgM抗体。
2. 2. The researcher used a sample of IgM antibodies to test their effectiveness.
   研究者使用一种样本的IgM抗体来测试其有效性。
3. 3. The IgM antibodies are crucial for fighting off infections.
   IgM抗体对于抵抗感染至关重要。