人血丙种球蛋白是一种重要的免疫球蛋白，其作用包括：

1. passively transfers immunological memory to recipients.
2. provides immediate but short-lived protection against infectious diseases.
3. can treat immune deficiencies, autoimmune diseases, and certain infections.
4. can be used as a prophylactic measure against diseases like hepatitis A, measles, and rubella.
5. helps modulate the immune response and reduce inflammation in autoimmune conditions.
6. serves as a crucial component in the treatment of certain neurologic disorders.

These functions make human immunoglobulin an essential therapeutic agent in various medical scenarios.