Detailed Instructions: In this task, you are given a sentence. You are expected to write the name of the organism substances in the body mentioned in the input. Although there might be several correct answers, you need to write one of them.
Q: Plasma from 182 patients with different malignant diseases was tested for riboflavin binding by immunoglobulins , which have been recently identified as major carriers of this micronutrient .
A:
Plasma