The WBC count and differential are a routine part of the complete blood count (CBC) test.
Lymphocytes are agranulocytes that are further separated into B-lymphocytes (make antibodies to attack bacteria/toxins) and T-lymphocytes (responsible for cell-mediated immunity such as attacking cells infected by viruses or attacking cancerous cells).
- Leukocytes or WBCs are differentiated into 5 different types:
- Basophils
- Eosinophils
- Lymphocytes
- Monocytes
- Neutrophils
The lymphocyte count is primarily useful in assessing viral illnesses, some atypical bacterial infections (especially pertussis) and some blood diseases.
The White Blood Cell (WBC) count and differential, which the lymphocyte count is part of, has clinical utility in:
- Evaluation of infection or inflammation
- Assist in determination of viral versus bacterial infection
- Assist in evaluation of the stage and severity of an infection
- Detect allergic response or parasitic infections (elevated eosinophils)
- Evaluation for hematologic malignancy/disorders
- Detecting and identifying various types of myelopoietic disorders
- Detecting and identifying various types of leukemia
- Evaluating bone marrow depression
- Evaluation of need for further tests, such as manual WBC differential or bone marrow biopsy
- Evaluation of drug effects, response to chemotherapy or radiation
- Evaluation of effect of cytotoxic agents
- Screening test as part of a CBC on admission to a health care facility or before surgery
Additional information:
- The interpretation of a normal, high or low result of any given WBC type requires the context of the patient's clinical condition, history and physical examination
- Specific patterns of leukocyte response are seen in various types of diseases as determined by the differential count
- The life span of leukocytes is normally 13–20 days, after which the cells are destroyed in the lymphatic system and are excreted from the body in fecal matter.
Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.
WBC Differential
| Conv. Units
(%) | SI Units
(fraction) |
|---|
| Birth | 26-36 | 0.26-0.36 |
| 2-8 weeks | 38-71 | 0.38-0.71 |
| 2-6 months | 42-72 | 0.42-0.72 |
| 7-12 months | 46-76 | 0.46-0.76 |
| 1-5 years | 46-76 | 0.46-0.76 |
| 6-17 years | 27-57 | 0.27-0.57 |
| Adults | 25-40 | 0.25-0.40 |
- Lymphocytosis is the condition of increased lymphocytes. It is important that not only the differential shows increased lymphocytes, but that the absolute number of lymphocytes is increased also (>4,000 cells/mm3 in adults or >9,000 cells/mm3 in children).
- In the event of the WBC's being >30,000/mm3 with lymphocytic predominance; bone marrow disorder/malignancy should be suspected.
- WBC's>100,000/mm3 is a medical emergency and immediate hematology/oncology consultation is needed.
Conditions, which may cause lymphocytosis include:
- Pathological:
- Blood diseases
- Agranulocytosis
- Aplastic anemia
- Banti's syndrome
- Felty's syndrome
- Heavy-chain disease
- Lymphocytic leukemia (acute or chronic)
- Multiple myeloma
- Chronic inflammatory conditions - Ulcerative colitis
- Drugs which may cause lymphocytosis include:
- Aminosalicylic acid
- Cefaclor
- Cefdinir
- Ceftazidime
- Chlorambucil
- Chlorpropamide
- Dexamethasone
- Gabapentin
- Granulocyte colony-stimulating factor
- Griseofulvin
- Haloperidol
- Levodopa
- Narcotics
- Niacinamide
- Ofloxacin
- Paroxetine
- Pergolide
- Propylthiouracil
- Quazepam
- Spironolactone
- Triazolam
- Valproic acid
- Venlafaxine
- Immune diseases
- Idiopathic thrombocytopenic purpura
- Serum sickness
- Infections
- Bacterial
- Brucellosis
- Paratyphoid
- Pertussis (almost always has lymphocytosis)
- Syphilis (Secondary and congenital)
- Tuberculosis
- Typhoid
- Viral
- Adenovirus
- Chicken pox
- Coxsackievirus A or B6
- Cytomegalovirus infections
- Echovirus
- Epstein Barr Virus (Infectious mononucleosis)
- Hepatitis (all infectious types)
- Herpes Simplex
- Herpes zoster
- HTLV-1 infection
- Measles
- Mumps
- Viral pneumonia
- Others
- Giardia lamblia
- Toxoplasmosis
- Metabolic
- Addison's disease (hypoadrenalism)
- Hyperthyroidism
- Others
- Alcohol
- Smoking
- Splenomegally (granulocytes will be sequestered which results in an increased percent of WBCs in circulation being lymphocytes)
- Physiological:
- Emotional stress
- Exercise
- Menstruation
- Newborns & Infants
Conditions, which may cause decreased lymphocytes (lymphopenia), include:
- Acute infections and illnesses
- Defects of lymphatic circulation
- Disorders of intestinal mucosa
- Intestinal lymphangiectasia
- Thoracic duct drainage
- Drugs causing decrease in lymphocytes include
- Alprazolam
- Asparaginase
- Benzodiazepines
- Bupropion
- Cefdinir
- Cefpodoxime
- Ceftriaxone
- Chlorambucil
- Cyclosporine
- Dexamethasone
- Eprosartan
- Fludarabine
- Folic acid
- Furosemide
- Glucocorticoids
- Hydrocortisone
- Ibuprofen
- Irinotecan
- Levetiracetam
- Levofloxacin
- Lithium
- Mechlorethamine
- Mirtazapine
- Muromonab-cd3
- Nelfinavir
- Niacin
- Ofloxacin
- Olsalazine
- Pamidronate
- Pentostatin
- Phenytoin
- Quazepam
- Rabeprazole
- Sirolimus
- Terbinafine
- Thiamine
- Trastuzumab
- Triazolam
- Immunodeficiency syndromes
- AIDS
- Congenital defects of cell mediated immunity
- Immunosuppressive medication
- Lymphopenia may occur with elevated corticosteroids levels due to:
- ACTH
- Corticosteroid therapy
- Cushing's syndrome
- Epinephrine
- Severe debilitating diseases
- Miliary tuberculosis
- Hodgkin's disease
- Lupus erythematosus
- Terminal carcinoma
- Renal failure