II. Characteristics

  1. Forms in Bone Marrow from Lymphoblasts (which are in turn derived from stem cells)
  2. Function: Primary source of viral defense and Antibody
    1. Adaptive Immunity (learned response)
      1. B-Lymphocyte
        1. Humoral Immunity with Antibody against extracellular Antigens
      2. T-Lymphocyte
        1. Cellular Immunity via T-Helper/CD4+ Cells and T-Cytotoxic/CD8+ Cells
    2. Innate Immunity
      1. Natural Killer Cells (NK cells)
        1. Lymphocytes providing immediate protection against Intracellular Bacteria, viruses, cancer cells
  3. Morphology on Blood Smear
    1. Mononuclear Leukocytes (same class as Monocytes)
    2. Small cells with minimal cytoplasm

III. Labs: Normal

  1. Percentage Lymphocytes: 15-40% of White Blood Cells
  2. Total Lymphocytes: 800-2600/mm3
  3. Total T Lymphocytes: 800-2200/mm3
    1. T helper Cells: >400/mm3
    2. T suppressor Cells: 250-750/mm3
    3. Helper Cell to Suppressor Cell ratio: >0.9
    4. CD2 Percentage of Lymphocytes: 65-85%
    5. CD4 Percentage of Lymphocytes: 45-75%

IV. Causes: Increased (Lymphocytosis)

  1. Increased Absolute Lymphocyte Count (>4500/mm3)
    1. Non-activated Lymphocytes
      1. Influenza
      2. Pertussis
      3. Tuberculosis
      4. Mumps
      5. Varicella
      6. Herpes Simplex Virus
      7. Rubeola
      8. Brucellosis
      9. Fungal infection
      10. Rickettsial infection
      11. Chronic Lymphocytic Leukemia
      12. Acute Lymphoblastic Leukemia
    2. Activated Lymphocytes (Atypical lymphocytes)
      1. Cytomegalovirus Infection
      2. Infectious Mononucleosis
      3. Infectious Viral Hepatitis
      4. Toxoplasmosis
      5. Syphilis
      6. Post-transfusion
      7. Beta Streptococcus
      8. Medication
        1. Mephenytoin
        2. Dilantin
        3. Para-Aminosalicylic Acid
  2. Increased Relative Lymphocyte Count (>40% of total)
    1. Normal finding in children under age 2 years
    2. Acute stage of Viral Infection
    3. Connective Tissue Disease
    4. Hyperthyroidism
    5. Addison's Disease
    6. Splenomegaly

V. Causes: Decreased

  1. AIDS
  2. Bone Marrow suppression
  3. Aplastic Anemia
  4. Neoplasms
  5. Steroids
  6. Adrenocortical hyperfunction
  7. Neurologic Disorders
    1. Multiple Sclerosis
    2. Myasthenia Gravis
    3. Gullain Barre Syndrome

VI. Evaluation: Lymphocytosis (Lymphocytes >4500/mm3)

  1. See Leukocytosis
  2. History and potential causes
    1. Contagious contacts
    2. Immunization history
  3. Diagnostics (consider)
    1. Viral specific studies (e.g. Monospot)
    2. Chest XRay

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Related Studies

Ontology: Lymphocyte (C0024264)

Definition (MSH) White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each), or NATURAL KILLER CELLS.
Definition (NCI_NCI-GLOSS) A type of immune cell that is made in the bone marrow and is found in the blood and in lymph tissue. The two main types of lymphocytes are B lymphocytes and T lymphocytes. B lymphocytes make antibodies, and T lymphocytes help kill tumor cells and help control immune responses. A lymphocyte is a type of white blood cell.
Definition (NCI) White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each); those with characteristics of neither major class are called null cells.
Definition (CSP) white blood cells formed in the body's lymphoid tissue.
Concepts Cell (T025)
MSH D008214
SnomedCT 56972008
LNC LP14540-6, LP30914-3, MTHU004645
English Lymphocytes, lymphocytes, lymph cell, lymphocyte, Lymphocyte (cell), Lymphocytic cell, Lymphocyte, NOS, Lymphocytic cell, NOS, Lymphocyte
Dutch lymfocyten, Lymfocyt, Lymfocyten
French Lymphocyte, Lymphocytes, Cellules lymphocytaires
Japanese リンパ球, リンパキュウ
Swedish Lymfocyter
Czech lymfocyty, Lymfocyty
Finnish Imusolut
Latvian Not Translated[Lymphocytes]
Polish Limfocyty
Hungarian Limfociták
Norwegian Lymfocytter
Spanish célula linfática, linfocito (célula), linfocito, Linfocitos
German Lymphozyten
Italian Linfociti
Portuguese Linfócitos

Ontology: Lymphocytosis (C0024282)

Definition (MSH) Excess of normal lymphocytes in the blood or in any effusion.
Definition (CSP) excess of normal lymphocytes in the blood or in any effusion.
Concepts Disease or Syndrome (T047)
MSH D008218
SnomedCT 267568006, 154832004, 67023009
English Lymphocytoses, LYMPHOCYTOSIS, lymphocytosis (diagnosis), lymphocytosis, Lymphocytosis [Disease/Finding], Lymphocytosis, Disorder characterized by lymphocytosis, Lymphocytosis (disorder), Lymphocytosis, NOS
French LYMPHOCYTOSE, Lymphocytose, Hyperlymphocytose
Portuguese LINFOCITOSE, Linfocitose
Spanish LINFOCITOSIS, linfocitosis (trastorno), linfocitosis, Linfocitosis
German LYMPHOZYTOSE, Lymphozytose
Japanese リンパ球増加症, リンパキュウゾウカショウ
Swedish Lymfocytos
Czech lymfocytóza, Lymfocytóza
Finnish Lymfosytoosi
Polish Limfocytoza
Hungarian lymphocytosis
Norwegian Lymfocytose
Dutch lymfocytose, Lymfocytose
Italian Linfocitosi

Ontology: Lymphocyte Count measurement (C0200635)

Definition (NCI) The determination of the number of lymphocytes in a blood sample.
Definition (NCI_CDISC) A measurement of the lymphocytes in a biological specimen.
Definition (MSH) The number of LYMPHOCYTES per unit volume of BLOOD.
Concepts Laboratory Procedure (T059)
MSH D018655
SnomedCT 446325007, 165535004, 142942007, 142948006, 74765001
English Lymphocyte Count, Lymphocyte Count, Total, Lymphocyte Counts, Lymphocyte Counts, Total, Total Lymphocyte Count, Total Lymphocyte Counts, Lymphocyte count NOS, Lymphocyte Count measurement, blood lymphocyte count, blood lymphocyte count (lab test), lymphocyte count, lymphocyte counts, total lymphocyte count, count lymphocytes, counts lymphocyte, lymphocyte number, count lymphocytes total, Total lymphocyte count (procedure), Total lymphocyte count, Lymphocyte count NOS (procedure), LYM, Lymphocytes, Lymphocyte Numbers, Lymphocyte Number, Lymphocyte count, Lymphocyte count (procedure)
Italian Conta linfocitaria, Numero dei linfociti, Conta totale linfocitaria, Conta dei linfociti
Swedish Lymfocytantal
Japanese リンパキュウスウ, リンパ球計数, リンパ球計算, リンパ球総数, リンパ球数
Czech lymfocyty - počet, Počet lymfocytů
Finnish Imusolumäärä
French Numération des lymphocytes, Numération lymphocytaire, Numération lymphocytaire totale, Taux de lymphocytes, Numération de lymphocytes
Polish Liczba limfocytów
Spanish recuento total de linfocitos (procedimiento), recuento total de linfocitos, Lymphocyte count NOS, recuento de linfocitos, SAI (procedimiento), recuento de linfocitos, SAI, recuento de linfocitos (procedimiento), recuento de linfocitos, recuento linfocítico, Recuento de linfocitos, Recuento de Linfocitos, Recuento Total de Linfocitos
Hungarian Limfocita szám
Norwegian Lymfocyttantall, Lymfocyttelling, Absolutt antall lymfocytter, Lymfocytt-telling
Portuguese Número de linfócitos, Contagem de Linfócitos, Contagem de Linfócitos Totais
Dutch lymfocytentelling, Lymfocytentelling, Lymfocytentelling, totale, Telling-, lymfocyten-
German Lymphozytenzahl, Lymphozytengesamtzahl, Lymphozytenzählung