Anti-immigrant, anti-Catholic, same difference in the 19th century politics of the know nothings. The point being they had an animus towards immigrants.
No, it's just interesting that you left out the most salient how's and why's of the Know-Nothing movement. It may be an indication that you don't really care why the Protestants might have carried such an attitude, or why they were wrong in certain ways and right in others. You also failed to point out how important the Scots-Irish Catholics were in America's colonial era and beyond. Either way, you revealed your shallow view of American history and culture. Naturally you'd fail to realize how critical the battle between Catholics and the Anglicant state church was to the process of America's founding. But you're a Dane, and somehow you're above all of this. Lutheran, I suppose?