The virus replicates first within epithelial cells in the pharynx (which causes pharyngitis, or sore throat), and later primarily within B cells (which are invaded via their CD21). The host<unk> mune response involves cytotoxic (CD8-positive) T cells against infected B lymphocytes, resulting in enlarged, atypical lymphocytes (Downey cells). When the infection is acute (recent onset, instead of chronic), heterophile antibodies are produced. Cytomegalovirus, adenovirus and Toxoplasma gondii (toxoplasmosis)<unk>  can cause symptoms similar to<unk> , but a heterophile antibody test will test negative and differentiate those<unk>  from<unk> .<unk>  is sometimes accompanied by secondary cold agglutinin disease, an autoimmune disease in which abnormal circulating antibodies directed against red blood cells can lead to a form of autoimmune hemolytic anemia. The cold agglutinin detected is of anti-i specificity.
Infectious mononucleosis
Chronic lymphocytic leukemia
Adult-onset Still's disease
Streptococcal pharyngitis
Post-Ebola virus syndrome
Acute lymphoblastic leukemia
Typhoid fever
Peritonsillar abscess