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Lymphocyte Mitogen 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 from patient|
|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 proliferation; pokeweed mitogen; PWM; phytohemagglutinin; PHA; Lymphocyte stimulation; lymphocyte proliferation; SCIDS; Severe combined immunodeficiency syndrome|
|Turn around times||10-12 days.|
|Additional information||Abnormal test results to mitogen 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 under-representation of T cells within the peripheral blood mononuclear cells (PBMCs) 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.
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 mitogens can be regarded as a more specific but less sensitive 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. One study has reported that the highest mitogen responses are seen in newborn infants with subsequent decline to 6 months of age, and a continuing decline through adolescence to half the neonatal response.(6) In our evaluation of 43 pediatric specimens (of all ages) with adult normal controls, only 21% and 14% were below the tenth percentile of the adult reference range for pokeweed (PWM) and phytohemagglutinin (PHA), respectively. 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.
Lymphocyte proliferation responses to mitogens and antigens are significantly affected by time elapsed since blood collection. Results have been shown to be variable for specimens assessed >24 and <48 hours postblood collection, therefore, lymphocyte proliferation results must be interpreted with due caution and results should be correlated with clinical context.
|Last Updated||3/24/2013 7:21:48 PM|
If you have additional questions regarding this test, please call: 415-353-1667