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mononuclear phagocyte system

ABBR: MPS. The system of fixed macrophages and circulating monocytes that serve as phagocytes, engulfing foreign substances in a wide variety of immune responses. SYN: reticuloendothelial system.


(mon″ō-noo″klē-ōʹsĭs) [mono- + nucleo- + -sis] Presence of an abnormally high number of mononuclear leukocytes in the blood.

infectious m. An acute, widespread infectious disease caused by the Epstein- Barr virus (EBV), a member of the herpesvirus group. The disease is sometimes referred to colloquially as the “kissing disease” because of its mode of transmission from person to person. SEE: Epstein-Barr virus.

 INCIDENCE: In the U.S., is most common in people between 15 and 25 years of age (high school- and college-age adolescents and young adults); beyond that age, most people are immune to EBV.

 CAUSES: The virus is transmitted in saliva and infects the epithelial cells of the oropharynx, nasopharynx, and salivary glands before spreading to lymphoid tissue (such as lymph nodes, spleen, liver) via infected B lymphocytes. The incubation period is 30 to 45 days.

 SYMPTOMS AND SIGNS: Infectious mononucleosis typically causes a sudden or gradual onset (7 to 14 days) of flulike symptoms. Findings include enlarged, tender cervical lymph nodes (lymphadenopathy), exudative tonsillitis, possible splenic enlargement and tenderness, and an enlarged spleen. Leukocytosis with atypical lymphocytes is present on blood smears. A maculopapular rash may be present early on. The infection usually lasts 2 to 4 weeks.

 Rarely, infectious mononucleosis is complicated by hemolytic anemia, enlargement of the liver, jaundice, meningoencephalitis, or pneumonitis. In Africa, latent EBV infection may be associated with the development of Burkittlymphoma.

 DIAGNOSIS: The disease is suggested in people between the ages of 10 and 30 who have pharyngitis, fatigue, petechiae on the palate, posterior cervical, auricular, inguinal, or widespread adenopathy; atypical lymphocytosis + 20% or 10% with 50% lymphocyte count; +/- a + heterophile Ab test. Monospot testing. Antibodies to viral capsid antibody of EBV (IgM, followed weeks later by IgG) can be used to determine the presence of acute infection. Differential diagnoses include bacterial meningitis, cytomegalovirus infection, cat scratch disease, allergic reactions to drugs (such as sulfa or phenytoin), German measles, strep throat, Toxoplasma gondii infection, and the acute onset of infection with HIV/AIDS.

 TREATMENT: There is no specific therapy for infectious mononucleosis; NSAIDs are used to treat fever, headache, sore throat, and myalgias. Corticosteroids may be used for complications (respiratory compromise secondary to severe pharyngeal swelling). Antiviral agents are used in severe disease. Full recovery is usual, after a period of convalescence lasting weeks or months.

 IMPACT ON HEALTH: Fatigue, muscle pains, and an increased need for sleep may persist for several months after the acute infection improves. From 2% ...

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