Lymphocytosis
Encyclopedia
Lymphocytosis is an increase in the number or proportion of lymphocyte
s in the blood, usually detected when a complete blood count
is routinely obtained. Lymphocytes normally represent 20 to 40% of circulating white blood cells. The absolute lymphocyte count (ALC) can be directly measured by flow cytometry
, or calculated by multiplying the total white blood cell
(WBC) count by the percentage of lymphocytes found in the differential count. In absolute lymphocytosis, the total lymphocyte count is elevated above the population reference range (normal). In adults, absolute lymphocytosis is present when the absolute lymphocyte count is greater than 4000 per microliter, in older children greater than 7000 per microliter and in infants greater than 9000 per microliter. Relative lymphocytosis occurs when there is a higher proportion (greater than 40%) of lymphocytes among the white blood cells, however, absolute lymphocyte count (ALC) is normal (less than 4000 per microliter. Relative lymphocytosis is normal in children under age 2.
Fever
, general malaise
, sore throat
, lymphadenopathy
, and atypical lymphocytes in the blood.
Causes of relative lymphocytosis include: age less than 2 years; acute viral
infections; connective tissue disease
s, thyrotoxicosis, Addison's disease
, and splenomegaly
with splenic sequestration of granulocytes.
Lymphocyte
A lymphocyte is a type of white blood cell in the vertebrate immune system.Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells...
s in the blood, usually detected when a complete blood count
Complete blood count
A complete blood count , also known as full blood count or full blood exam or blood panel, is a test panel requested by a doctor or other medical professional that gives information about the cells in a patient's blood...
is routinely obtained. Lymphocytes normally represent 20 to 40% of circulating white blood cells. The absolute lymphocyte count (ALC) can be directly measured by flow cytometry
Flow cytometry
Flow cytometry is a technique for counting and examining microscopic particles, such as cells and chromosomes, by suspending them in a stream of fluid and passing them by an electronic detection apparatus. It allows simultaneous multiparametric analysis of the physical and/or chemical...
, or calculated by multiplying the total white blood cell
White blood cell
White blood cells, or leukocytes , are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...
(WBC) count by the percentage of lymphocytes found in the differential count. In absolute lymphocytosis, the total lymphocyte count is elevated above the population reference range (normal). In adults, absolute lymphocytosis is present when the absolute lymphocyte count is greater than 4000 per microliter, in older children greater than 7000 per microliter and in infants greater than 9000 per microliter. Relative lymphocytosis occurs when there is a higher proportion (greater than 40%) of lymphocytes among the white blood cells, however, absolute lymphocyte count (ALC) is normal (less than 4000 per microliter. Relative lymphocytosis is normal in children under age 2.
Symptoms
Lymphocytosis is a feature of infection, particularly in children. In the elderly, lymphoproliferative disorders, including chronic lymphocytic leukaemia and lymphomas, often present with lymphadenopathy and a lymphocytosis.Fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, general malaise
Malaise
Malaise is a feeling of general discomfort or uneasiness, of being "out of sorts", often the first indication of an infection or other disease. Malaise is often defined in medicinal research as a "general feeling of being unwell"...
, sore throat
Sore throat
A sore throat or throat pain is a common physical symptom usually caused by acute pharyngitis, or throat inflammation, though it also occurs in a number of other situations, such as post trauma and in diphtheria. It can cause mild to extreme pain....
, lymphadenopathy
Lymphadenopathy
Lymphadenopathy is a term meaning "disease of the lymph nodes." It is, however, almost synonymously used with "swollen/enlarged lymph nodes". It could be due to infection, auto-immune disease, or malignancy....
, and atypical lymphocytes in the blood.
Causes
Causes of absolute lymphocytosis include:- acute viralVirusA virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
infections, such as infectious mononucleosisInfectious mononucleosisInfectious mononucleosis is an infectious, widespread viral...
(glandular fever), hepatitisHepatitisHepatitis is a medical condition defined by the inflammation of the liver and characterized by the presence of inflammatory cells in the tissue of the organ. The name is from the Greek hepar , the root being hepat- , meaning liver, and suffix -itis, meaning "inflammation"...
and CytomegalovirusCytomegalovirusCytomegalovirus is a viral genus of the viral group known as Herpesviridae or herpesviruses. It is typically abbreviated as CMV: The species that infects humans is commonly known as human CMV or human herpesvirus-5 , and is the most studied of all cytomegaloviruses...
infection - other acute infections such as pertussisPertussisPertussis, also known as whooping cough , is a highly contagious bacterial disease caused by Bordetella pertussis. Symptoms are initially mild, and then develop into severe coughing fits, which produce the namesake high-pitched "whoop" sound in infected babies and children when they inhale air...
- some protozoal infections, such as toxoplasmosisToxoplasmosisToxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. The parasite infects most genera of warm-blooded animals, including humans, but the primary host is the felid family. Animals are infected by eating infected meat, by ingestion of feces of a cat that has itself...
and American trypanosomiasis (Chagas diseaseChagas diseaseChagas disease is a tropical parasitic disease caused by the flagellate protozoan Trypanosoma cruzi. T. cruzi is commonly transmitted to humans and other mammals by an insect vector, the blood-sucking insects of the subfamily Triatominae most commonly species belonging to the Triatoma, Rhodnius,...
) - chronic intracellular bacterial infections such as tuberculosisTuberculosisTuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...
or brucellosisBrucellosisBrucellosis, also called Bang's disease, Crimean fever, Gibraltar fever, Malta fever, Maltese fever, Mediterranean fever, rock fever, or undulant fever, is a highly contagious zoonosis caused by ingestion of unsterilized milk or meat from infected animals or close contact with their secretions... - Chronic lymphocytic leukemiaChronic lymphocytic leukemiaB-cell chronic lymphocytic leukemia , also known as chronic lymphoid leukemia , is the most common type of leukemia. Leukemias are cancers of the white blood cells . CLL affects B cell lymphocytes. B cells originate in the bone marrow, develop in the lymph nodes, and normally fight infection by...
- Acute lymphoblastic leukemiaAcute lymphoblastic leukemiaAcute lymphoblastic leukemia is a form of leukemia, or cancer of the white blood cells characterized by excess lymphoblasts.Malignant, immature white blood cells continuously multiply and are overproduced in the bone marrow. ALL causes damage and death by crowding out normal cells in the bone...
Causes of relative lymphocytosis include: age less than 2 years; acute viral
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
infections; connective tissue disease
Connective tissue disease
A connective tissue disease is any disease that has the connective tissues of the body as a target of pathology. Connective tissue is any type of biological tissue with an extensive extracellular matrix that supports, binds together, and protects organs...
s, thyrotoxicosis, Addison's disease
Addison's disease
Addison’s disease is a rare, chronic endocrine disorder in which the adrenal glands do not produce sufficient steroid hormones...
, and splenomegaly
Splenomegaly
Splenomegaly is an enlargement of the spleen. The spleen usually lies in the left upper quadrant of the human abdomen. It is one of the four cardinal signs of hypersplenism, some reduction in the number of circulating blood cells affecting granulocytes, erythrocytes or platelets in any...
with splenic sequestration of granulocytes.