Editing Infectious mononucleosis (section)

==Pathophysiology==
The virus replicates first within [[epithelium|epithelial cell]]s in the [[Human pharynx|pharynx]] (which causes [[pharyngitis]], or sore throat), and later primarily within [[B cell]]s (which are invaded via their [[Complement receptor 2|CD21]]). The host immune response involves cytotoxic (CD8-positive) [[T cell]]s against infected B lymphocytes, resulting in enlarged, reactive lymphocytes ([[Reactive lymphocyte|Downey cells]]).<ref name="eMedicine">{{eMedicine|ped|705}}</ref>

When the infection is acute (recent onset, instead of [[chronic (medicine)|chronic]]), [[heterophile]] [[antibodies]] are produced.<ref name=Ebell2004/>

[[Human cytomegalovirus|Cytomegalovirus]], [[Adenovirus infection|adenovirus]] and ''[[Toxoplasma gondii]]'' ([[toxoplasmosis]]) infections can cause symptoms similar to infectious mononucleosis, but a [[heterophile antibody test]] will test negative and differentiate those infections from infectious mononucleosis.<ref name=CDC2014Eb/><ref>{{cite web |url=http://www.gorhams.dk/html/the_lymphatic_system.html |title=The Lymphatic System |publisher=Lymphangiomatosis & Gorham's disease Alliance |access-date=2010-02-08 |url-status=dead |archive-url=https://web.archive.org/web/20100128094840/http://www.gorhams.dk/html/the_lymphatic_system.html |archive-date=2010-01-28 }}</ref>

Mononucleosis is sometimes accompanied by secondary [[cold agglutinin disease]], an [[autoimmune disease]] in which abnormal circulating antibodies directed against [[red blood cell]]s can lead to a form of [[autoimmune hemolytic anemia]]. The cold agglutinin detected is of [[Ii antigen system|anti-i]] specificity.<ref name="Mayo_Textbook">{{cite book |author1=Ghosh, Amit K. |author2=Habermann, Thomas |title=Mayo Clinic Internal Medicine Concise Textbook |publisher=Informa Healthcare |year=2007 |isbn=978-1-4200-6749-1 }}</ref><ref>{{Cite journal |author= Rosenfield RE |author2=Schmidt PJ |author3=Calvo RC |author4=McGinniss MH  |title= Anti-i, a frequent cold agglutinin in infectious mononucleosis |journal= Vox Sanguinis |volume= 10 |issue= 5 |pages= 631–634 |doi= 10.1111/j.1423-0410.1965.tb01418.x |pmid= 5864820 |year= 1965|s2cid=30926697 }}</ref>