The process in which an antigen-presenting cell expresses antigen (peptide or lipid) of exogenous origin on its cell surface in association with an MHC protein complex. [ http://www.ncbi.nlm.nih.gov/pubmed/15928678 http://www.ncbi.nlm.nih.gov/pubmed/15771591 http://openisbn.com/search.php?q=0781735149&isbn=1/ GOC:add ]