immunoreactivity
/ˌɪmjʊnəʊˌriːakˈtɪvɪti/ /ɪˌmjuːnəʊˌriːakˈtɪvɪti/Medicine and Biology
noun
The property or state of being immunoreactive. Also: the content or quantity of a specific immunoreactive substance in blood, tissue, etc.
Origin
1960s; earliest use found in American Journal of Medicine. From immuno- + reactivity, after immunoreactive.