<unk> s are usually associated with viral illnesses, but they can also be present as a result of drug reactions (such as phenytoin), immunizations, radiation, and hormonal causes (such as stress and Addison's disease), as well as some autoimmune disorders (such as rheumatoid arthritis). Some pathogen-related causes include: * Epstein–Barr virus * Cytomegalovirus * Toxoplasma gondii * Treponema pallidum (syphilis) * Streptococcus agalactiae (group B streptococci) * Hepatitis C * Hantavirus
Reactive lymphocyte
Tingible body macrophage
Mast cell
Plasma cell
Dendritic cell
Prolymphocyte
Passenger leukocyte
Nonspecific immune cell