Lymphocyte Proliferation, Antigens, Blood

CPT CODE:

USEFUL FOR:

Evaluating patients suspected of having diminished cellularimmune function(2)

SPECIMEN REQUIRED:

Specimen must arrive within 24 hours of draw and by10 a.m. on Friday. Send specimen Sunday throughThursday only. Draw blood in a green top (sodium heparin) tube(s), and send 15 mL of sodium heparin whole blood in original VACUTAINER(S). (Lithiumheparin is not acceptable.) Do not aliquot. Forward promptlyat ambient temperature only.Note:    1. Specify "Antigen" to differentiate from "Mitogen"                  testing. This information is required for processing.             2.  If both antigens and mitogens are desired, order #89368                  "Lymphocyte Proliferation Panel for Mitogens and                   Antigens."             3.  Specific antigen testing is not available.             4. Draw date and time and ordering physician name              and phone number are required on request form for                 processing.5.  For serial monitoring, we recommend that specimen                 draws be performed at the same time of day.

TRANSPORT TEMPERATURE:

Ambient\Refrig NO\Frozen NO 

CLINICAL INFORMATION:

Several classes of ligands are capable of inducing blastogenesis and stimulating proliferation of lymphocytes in vitro, including recall antigens (eg, Candida albicans and tetanus toxoid), plant mitogens (phytohemagglutinin [PHA], pokeweed [PWM], and concanavalin A [Con A]), bacterial products and superantigens (potent bacterial toxins that at low concentrations have the ability to activate large numbers of T-cells), and phorbol esters. Cellular proliferation follows a complex series of signals that begins with engagement of lymphocyte surface receptors by a mitogenic ligand. Subsequent signals, including gene activation and secretion of cytokines, result in synthesis of DNA and cell division. Measurement of antigen-induced lymphocyte proliferation in vitro using recall antigens as stimuli provides an indication of cell mediated immunity.(1) Lymphocyte proliferation induced by recall antigens is a T-cell dependent response. Diminished (nonreactive) responses to recall antigens occur in a variety of primary and secondary immunodeficiency diseases that affect T lymphocytes.(2) The absolute counts of lymphocyte subsets are known to be influenced by a variety of biological factors, including hormones, the environment,and temperature. The studies on diurnal (circadian) variation in lymphocyte counts have demonstrated progressive increase in CD4 T-cell count throughout the day, while CD8 T cells and CD19 B cells increase between 8:30 am and noon, with no change between noon and afternoon. Natural killer (NK) cell counts, on the other hand, are constant throughout the day.(3)Circadian variations in circulating T-cell counts have been shown to be negatively correlated with plasma cortisol concentration.(4-6) In fact, cortisol and catecholamine concentrations control distribution and, therefore, numbers of naive versus effector CD4 and CD8 T cells.(4) It is generally accepted that lower CD4 T-cell counts are seen in the morning compared with the evening (7), and during summer compared to winter.(8) These data, therefore, indicate that timing and consistency in timing of blood collection is critical when serially monitoring patients for lymphocyte subsets.

CLINICAL INTERPRETATION:

Diminished (nonreactive) responses to recall antigens areconsistent with a primary or secondary immunodeficiency diseasethat affects T lymphocytes (cellular immunity). Nonreactive responses are not specific for a particular disease and do not indicate the degree of immunodeficiency.

REFERENCE VALUES:

Maximum Stimulating Index (S.I.) >3 = Reactive (positive)

Maximum Stimulating Index (S.I.) <=3 = Non-reactive (negative)

All Lymphocyte Proliferation, Antigen assays reported have a cell viability of >85%.