normal opsonin

nor·mal op·so·nin

opsonin normally present in the blood, that is, without stimulation by a known, specific antigen such as certain complement components; it is relatively thermolabile and reacts with various organisms.

nor·mal op·so·nin

(nōr'măl op'sŏ-nin)
That normally present in the blood without stimulation by a specific antigen; it is relatively thermolabile and reacts with various organisms.