a blood serum (= a thin yellowish liquid taken from blood) that contains antibodies (= proteins produced to fight disease) against a particular virus, bacterium, etc., used to treat or protect against disease

There may be a delayed allergic reaction to the injection of an antiserum, caused by an antibody reaction to an antigen in the donor serum. 注射抗血清之后，可能会发生延迟的过敏反应，原因是针对供体抗原的抗体反应。