Blastogenesis Antigens Immune Competence Lymphocyte Blastogenesis Antigen Lymphocyte Phytohemagglutiin Lymphocyte Transformation
If insufficient peripheral blood mononuclear cells (PBMCs) are isolated from the patient's sample due to low WBC counts or specimen volume received, selected dilutions or stimulants may not be tested at the discretion of the laboratory to ensure the most reliable results. Testing with 1 stimulant will always be performed. When adequate specimen is available for both stimulants to be tested, an additional test ID will be reflexed and billed separately.
Assessing T-cell function in patients on immunosuppressive therapy, including solid-organ transplant patients
Evaluating patients suspected of having impairment in cellular immunity
Evaluation of T-cell function in patients with primary immunodeficiencies, either cellular (DiGeorge syndrome, T-negative severe combined immunodeficiency: SCID, etc) or combined T- and B-cell immunodeficiencies (T- and B-negative SCID, Wiskott Aldrich syndrome, ataxia telangiectasia, common variable immunodeficiency, among others) where T-cell function may be impaired
Evaluation of T-cell function in patients with secondary immunodeficiency, either disease related or iatrogenic
Evaluation of recovery of T-cell function and competence following bone marrow transplantation or hematopoietic stem cell transplantation
This test is not intended for assessment of maternal engraftment.
Specimens are required to be received in the Mayo Clinic Laboratory weekdays and by 4 p.m. on Friday. Draw and package specimen as close to shipping time as possible. Ship specimen overnight.
It is recommended that specimens arrive within 24 hours of draw.
Samples arriving on the weekend and observed holidays may be canceled.
1. Date and time of draw and ordering physician name and phone number are required.
2. Specifiy Antigen only or Mitogen and Antigen.
This test should not be ordered for patients younger than 3 months of age unless there is a clinical history of candidiasis. See the Cautions section for additional information.
<3 months: 1 mL
3-24 months: 3 mL
25 months-18 years: 5 mL
>18 years: 20 mL
Specimen Minimum Volume:
<6 years: 1 mL 6-18 years: 2 mL >18 years: 6 mL
For serial monitoring, we recommend that specimen draws be performed at the same time of day. See Cautions section.
Collection Instructions: Send specimen in original tube. Do not aliquot.
Blood Volume Recommendations Based on Absolute Lymphocyte Count (ALC)
There is no clinical utility to assessing antigen responses in infants younger than 3 months old due to limited antigen exposure and vaccination. The only exception would be infants who develop candidiasis prior to 3 months of age.
When interpreting results, note that the range of lymphocyte proliferative responses observed in healthy, immunologically competent individuals is large. The reference ranges provided will be helpful in ascertaining the magnitude of the normal response.
Lymphocyte proliferation to mitogens is known to be affected by concomitant use of steroids, immunosuppressive agents, including cyclosporine, tacrolimus (FK506), Cellcept (mycophenolate mofetil), immunomodulatory agents, alcohol, and physiological and social stress.
Lymphocyte proliferation responses to antigens (and mitogens) are significantly affected by time elapsed since blood collection. Results have been shown to be variable for specimens assessed between 24 and 48 hours post-blood collection. Therefore, lymphocyte proliferation results must be interpreted with due caution and results should be correlated with clinical context. Specimens more than 24-hours old may yield spurious results.
Diminished results may be obtained in cultures that contain excess neutrophils or nonviable cells.(6)
Timing, and consistency in timing, of blood collection is critical when serially monitoring patients lymphocyte subsets (specifically T cells in this context) and their diurnal variation can potentially affect the magnitude of the proliferative response, especially in patients who already have severe T-cell lymphopenia. 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 a.m. and noon, with no change between noon and afternoon. Natural killer (NK)-cell counts, on the other hand, are constant throughout the day. Circadian variations in circulating T-cell counts negatively correlate with plasma cortisol concentration. In fact, cortisol and catecholamine concentrations control distribution and, therefore, numbers of naive versus effector CD4 and CD8 T cells. It is generally accepted that lower CD4 T-cell counts are seen in the morning compared with the evening and during summer compared to winter.
Monday through Friday
Do not send specimen after Thursday.
Viability of lymphocytes at day 0: > or =75.0%
Maximum proliferation of Candida albicans as % CD45: > or =5.7%
Maximum proliferation of Candida albicans as % CD3: > or =3.0%
Maximum proliferation of tetanus toxoid as % CD45: > or =5.2%
Maximum proliferation of tetanus toxoid as % CD3: > or =3.3%
Abnormal test results to antigen stimulation are indicative of impaired T-cell function, if T-cell counts are normal or only modestly decreased. If there is profound T-cell lymphopenia, there could be a dilution effect with underrepresentation of T cells within the peripheral blood mononuclear cell (PBMC) population that could result in lower T-cell proliferative responses. However, this is not a significant concern in the flow cytometry assay, since acquisition of additional cellular events during analysis can compensate for artificial reduction in proliferation due to lower T-cell counts. In the case of antigen-specific T-cell responses to tetanus toxoid (TT), there can be absent responses due to natural waning of cellular immunity, if the interval between vaccinations has exceeded the recommended period, especially in adults. In such circumstances, it would be appropriate to measure TT-specific T-cell responses 4 to 6 weeks after a booster vaccination.
There is no absolute correlation between T-cell proliferation in vitro and a clinically significant immunodeficiency, whether primary or secondary, since T-cell proliferation in response to activation is necessary, but not sufficient, for an effective immune response. Therefore, the proliferative response to antigens can be regarded as a more sensitive, but less specific, test for the diagnosis of infection susceptibility.
There is no single laboratory test that can identify or define impaired cellular immunity, with the exception of an opportunistic infection.
Controls in this laboratory and most clinical laboratories are healthy adults. Since this test is used for screening and evaluating cellular immune dysfunction in infants and children, it is reasonable to question the comparability of proliferative responses between healthy infants, children, and adults. It is reasonable to expect robust T-cell-specific responses to TT in children without cellular immune compromise, as a result of repeated childhood vaccinations. The response to Candida albicans can be more variable depending on the extent of exposure and age of exposure. A comment will be provided in the report documenting the comparison of pediatric results with an adult reference range and correlation with clinical context for appropriate interpretation.
Without obtaining formal pediatric reference values, there remains a possibility that the response in infants and children can be underestimated. However, the practical challenges of generating a pediatric range for this assay necessitate comparison of pediatric data with adult reference values or controls.