Overview

• T-lymphocytes (cell-mediated immunity) and B-lymphocytes (precursors of plasma cells) - humoral antibody/immunoglobulin production populations; a small, third group are 'null' cells - function unknown.
• May not be differentiated on the basis of light microscopic morphology alone.
• T-lymphocytes, in particular, can recirculate between blood and lymph nodes.

Sampling

Tests

Methodologies

• Manual hemocytometer - accuracy +/- 20-25%.
• Electronic counting systems - accuracy +/- 3-5% (intralaboratory precision) or +/- 10-15% (interlaboratory precision).
• Some in-practice analyzers or cell counting methods available.

Availability

• Widely available at commercial laboratories.

Validity

Sensitivity

• Sensitive.

Specificity

• Non-specific.

Predictive value

• Non-specific.

Technician (extrinsic) limitations

• Some experience is required for accurate identification of leukocytes.

Result Data

Further Reading

Publications

Refereed papers

• Recent references from VetMedResource and PubMed.

Other sources of information

• Cowell R L, Tyler R D & Meinkoth J H (1999) Diagnostic Cytology and Hematology of the Dog and Cat. 2nd edn. Mosby, USA.
• Duncan J R, Prasse K W & Mahaffy E A (1994) Veterinary Laboratory Medicine Clinical Pathology. 3rd edn. Iowa University Press, USA.
• Jain N C (1993) Essentials of Veterinary Hematology. Lea & Febiger, USA.