immuunsem
Immuunsem is a term that appears to be a misspelling or a non-standard word in common usage. It is possible that it is a portmanteau or a neologism, but without further context, its precise meaning is unclear. In the context of linguistics or biology, the root "immuun" relates to immunity, which is the body's ability to resist a particular infection or toxin by the action of specific antibodies or sensitized white blood cells. The addition of "sem" does not correspond to any established suffix or prefix that would clarify its meaning.
If "immuunsem" is intended to refer to a specific concept, more information would be needed. For example,