HP and infection: Acute phase proteins (APPs)are plasma proteins whose concentrationis related to inflammation and changes after trauma or infection.According to their response after a challenge, APP can be classifiedas positive APP when plasma concentration increases after an aggression,like haptoglobin (HP), pig-MAP, serum amyloid A (SAA), C-reactiveprotein (CRP), and alpha-2-HS-glycoprotein, or negative APP if theirconcentration drops, like apolipoprotein A1 (APOA1), serum albumin,or transthyretin.