Nonmalignant disorders of lymphocytes.

OBJECTIVE

To review the etiology, pathophysiology, clinical features, and laboratory findings in nonmalignant disorders of lymphocytes.

DATA SOURCES: Current literature.

STUDY SELECTION: Determined by author.

DATA EXTRACTION: Determined by author.

DATA SYNTHESIS: Assessing qualitative and quantitative changes in lymphocytes provides important information regarding immune reactions, disease conditions, and responses to therapy. Quantitative nonmalignant disorders encompass those conditions in which the total number of lymphocytes may be either increased (lymphocytosis) or decreased (lymphocytopenia). Frequently encountered disorders with a lymphocytosis include infectious mononucleosis and cytomegalovirus infection. Lymphocytopenia is not detected as often or as easily in the clinical laboratory, but may be induced by several causes such as stress, certain types of therapy, nutrient deficiencies, or premature destruction of lymphocytes as occurs in acquired immunodeficiency syndrome. Clinical and laboratory findings provide significant clues in defining the etiology of a nonmalignant disorder of lymphocytes.

CONCLUSION

Disorders of lymphocytes include both benign and malignant quantitative and qualitative variations. A reactive lymphocytosis is commonly associated with many viral and certain bacterial infections. The clinical laboratory plays an important role in differentiating reactive and malignant lymphoproliferative processes. Benign lymphocytopenia, although not a frequent finding, must also be characterized by the laboratory.