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Discussion on Immunity to parasites
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Member:
Annknigh
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Posted on Thursday, Apr 28, 2005 - 4:09 am:
Dr O,
In several places on the forum, I have seen reference to horses developing immunity to certain parasites. Most recently I saw it referenced that young horses often develop immunity to ascarids.
Could you explain this further and why is immunity developed towards certain parasites and not others. And what exactly does this mean, that if immunity is developed, does the immune system totally destroy all of that type or do they exist systemically but the immune system is able to regulate the numbers? Any idea what aspect of the immune system targests these?
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Moderator:
DrO
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Posted on Thursday, Apr 28, 2005 - 10:45 am:
Hello Ann,
We don't know the answer to your question on why better immunity is developed toward rounds but not towards strongyles. But even in the case of rounds they are not totally controlled in adults by the immune system. There appear to be a number of mechanisms, all poorly understood, at work that increase the resistance of a horse to parasites. Concerning specific immune responses they are mainly T-Helper cell dependent. Antibody protection alone is not sufficient to remove parasites and mast cells, eosinophils and goblet cell hyperplasia (along with concommitent increased mucous secretion) also play a part in repulsing parasites. We have much to learn about this important topic.
DrO
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