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Lymphocyte Antigen Stimulation
|Collection Instructions||Collect blood Monday through Thursday only. For Brown & Toland patients Authorization from B&T is required before samples are collected.
Specimens must arrive at Mayo laboratories within 24 hours of collection, therefore samples must be drawn and delivered to UCSF laboratory by 12:00 noon to meet processing deadline.
|Container type||Dark Green top|
|Amount to Collect||6 mL blood|
|Sample type||Heparinized whole blood|
|Preferred volume||6 mL blood|
|UCSF Rejection Criteria||Samples collected outside of stated time frames|
|Processing notes||Specimen must be maintained at room temperature. Do not refrigerate or freeze.
Specimen must be received for sendout at China Basin by 3:30 pm on day of collection.
Please notify China Basin Sendout to expedite processing of whole blood specimens (Dark Green tubes) at 3-1349 or 3-4840 upon receipt.
|Synonyms||Lymphocyte stimulation; lymphocyte antigen proliferation; lymphocyte proliferation, SCIDS; Severe combined immunodeficiency syndrome; C. albicans; Candida albicans; tetanus toxoid|
|Turn around times||10-12 days.|
|Additional information||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, it must be kept in mind that there could be a "dilution" effect with underrepresentation of T cells within the peripheral blood mononuclear cells (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.
It should also be kept in mind that 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.
It should be noted that without obtaining formal pediatric reference values, it 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.
|Last Updated||3/24/2013 7:21:19 PM|