During infection, the acute phase response triggers the release of acute phase proteins (APP), alpha-(1) acid glycoprotein (AGP), serum amyloid A (SAA) and Pig-MAP into the circulation, accompanied by a decrease in plasma levels of transthyretin. We quantified the association between these APP in 26 apparently healthy pigs from two breeds, 13 Large White and 13 Meishan (16 male; 10 female). There was a significant correlation between plasma levels of haptoglobin and Pig-MAP (r=0.57; p<0.05), but no significant associations between any of the other APP tested. We also measured the relationship between PigMAP, transthyretin and SAA, and the proportions of peripheral blood mononuclear sub-sets, CD8(+) cells, CD4(+) cells, CD11R1(+) cells, MHC DQ(+) cells, and monocytes. There were correlations between both plasma levels of Pig-MAP and the proportion of monocytes (r=0.55; p<0.05) and plasma levels of transthyretin and the proportion of MHC DQ(+) cells (r=0.40; p<0.01). Breed and sex influenced plasma levels of Pig-MAP but not plasma levels of transthyretin. Overall, these results suggest closer links between the mechanisms that regulate the release haptoglobin, Pig-MAP and monocytes compared to those that regulate the release of AGP, SAA and transthyretin.