Anti-pro BNP" appears to be a typo or an incomplete term. It's possible you are referring to "pro-B-type natriuretic peptide" (pro-BNP), which is a precursor molecule to B-type natriuretic peptide (BNP). BNP is a hormone produced by the heart in response to stretching of heart muscle cells and is used as a diagnostic marker for heart-related conditions, particularly heart failure.