Methods for measuring ubiquitin carboxy-terminal hydrolase L1 levels in blood
Disclosed herein are improved methods of processing, measuring, and detecting levels of ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) in blood samples taken from a human subject at time points within about 8 hours (or about 8 hours or less) after obtaining the sample from the subject. UCH-L1 is an early biomarker for traumatic brain injury (TBI), and there is a need for improved methods for assessing UCH-L1 in blood can aid in the diagnosis and evaluation of a human subject who has sustained or may have sustained a head injury.
1. In an improvement of a method of measuring an amount of ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) in a whole blood sample obtained from a subject, wherein said improvement comprises processing the sample within no more than about eight hours after the sample is obtained from the subject to avoid a rise in UCH-L1 level that results from storage of the sample, wherein processing the sample comprises:
(a) separating plasma from blood cells in the sample and, subsequently performing a test using the plasma that measures the amount of UCH-L1;
(b) separating serum from any clots that arise in the sample and subsequently performing a test using the serum that measures the amount of UCH-L1; or
(c) performing a test that measures the amount of UCH-L1 in the sample, wherein the test is selected from the group consisting of an immunoassay, chemical analysis, SDS PAGE and Western blot analysis, electrophoresis analysis, a protein assay, a competitive binding assay, a functional protein assay, chromatography, and spectrophotometry thereby, avoiding a rise in UCH-L1 level that results from storage of the sample.
2. The improvement of claim 1 , wherein the sample is processed within:
(i) a period of time after the sample is obtained from the subject selected from the group consisting of: (a) from about zero hours to about 6 hours; (b) from about zero hours to about 4 hours; (c) from about zero hours to about 2 hours; and (d) from about zero hours to about 1 hour; or
(ii) a period of time after the sample is obtained from the subject selected from the group consisting of: (a) from about 1 hour to about 8 hours; (b) from about 1 hour to about 6 hours; (c) from about 1 hour to about 4 hours; and (d) from about 1 hour to about 2 hours.
3. The improvement of claim 1 , wherein the sample is:
(a) obtained from the subject using a container comprising an anticoagulant selected from the group consisting of heparin and ethylenediaminetetraacetic acid (EDTA); or
(b) collected using a serum collection tube.
4. The improvement of claim 1 , wherein the test is employed in a clinical chemistry format.
5. The improvement of claim 1 , wherein the test is an immunoassay comprising:
(a) contacting the sample, either simultaneously or sequentially, in any order with:
(1) at least one capture antibody, which binds to an epitope on UCH-L1 or a UCH-L1 antigen-binding fragment to form a capture antibody-UCH-L1 antigen complex, and
(2) at least one detection antibody which includes a detectable label and binds to an epitope on UCH-L1 that is not bound by the capture antibody, to form a UCH-L1 antigen-detection antibody complex,
such that a capture antibody-UCH-L1 antigen-detection antibody complex is formed, and
(b) measuring the amount or concentration of UCH-L1 in the sample based on the signal generated by the detectable label in the capture antibody-UCH-L1 antigen-detection antibody complex.
6. The improvement of claim 1 , wherein the sample is:
(a) maintained at room temperature for some period of time during the time point that the sample is obtained from the subject to a time point when the test is performed;
(b) maintained at a temperature from about 2° C. to about 8° C. for some period of time during the time point that the sample is obtained from the subject to the time point when the test is performed; or
(c) not mixed during the period of time after the sample is obtained from the subject to the time point when the test is performed.
7. The improvement of claim 1 , wherein the UCH-L1 amount in the sample from the subject is assessed as a measure of traumatic brain injury, wherein the subject has sustained or may have sustained an injury to the head.
8. A method of avoiding or preventing an increase or rise in ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) levels between the period of time a whole blood sample is obtained from a subject and prior to performing an assay on the sample, the method comprising the step of: processing the sample within no more than about eight hours after the sample is obtained from the subject to avoid an increase or rise in UCH-L1 level that results from storage of the sample prior to performing the assay, wherein processing the sample comprises:
(a) separating plasma from blood cells in the sample and, subsequently performing an assay using the plasma that measures the amount of UCH-L1 in the sample;
(b) separating serum from any clots that arise in the sample; and, subsequently performing an assay using the serum that measures the amount of UCH-L1; or
(c) performing an assay that measures the amount of UCH-L1 in the sample, wherein the assay is selected from the group consisting of an immunoassay, chemical analysis, SDS PAGE and Western blot analysis, electrophoresis analysis, a protein assay, a competitive binding assay, a functional protein assay, chromatography, and spectrophotometry; to thereby, avoid or prevent an increase or rise in UCH-L1 level that results from storage of the sample.
9. The method of claim 8 , wherein the sample is processed within:
(i) a period of time after the sample is obtained from the subject selected from the group consisting of: (a) from about zero hours to about 6 hours; (b) from about zero hours to about 4 hours; (c) from about zero hours to about 2 hours; and (d) from about zero hours to about 1 hour; or
(ii) a period of time after the sample is obtained from the subject selected from the group consisting of: (a) from about 1 hour to about 8 hours; (b) from about 1 hour to about 6 hours; (c) from about 1 hour to about 4 hours; and (d) from about 1 hour to about 2 hours.
10. The method of claim 8 , wherein the sample is:
(a) obtained from the subject using a container comprising an anticoagulant selected from the group consisting of heparin and ethylenediaminetetraacetic acid (EDTA); or
(b) collected using a serum collection tube.
11. The method of claim 8 , wherein the assay is employed in a clinical chemistry format.
12. The method of claim 8 , wherein the assay is an immunoassay comprising:
(a) contacting the sample, either simultaneously or sequentially, in any order with:
(1) at least one capture antibody, which binds to an epitope on UCH-L1 or a UCH-L1 antigen-binding fragment to form a capture antibody-UCH-L1 antigen complex, and
(2) at least one detection antibody which includes a detectable label and binds to an epitope on UCH-L1 that is not bound by the capture antibody, to form a UCH-L1 antigen-detection antibody complex, such that a capture antibody-UCH-L1 antigen-detection antibody complex is formed, and
(b) measuring the amount or concentration of UCH-L1 in the sample based on the signal generated by the detectable label in the capture antibody-UCH-L1 antigen-detection antibody complex.
13. The method of claim 8 , wherein the sample is:
(a) maintained at room temperature for some period of time between the time point that the sample is obtained from the subject and the time point when the assay is performed;
(b) maintained at a temperature from about 2° C. to about 8° C. for some period of time during the time point that the sample is obtained from the subject to the time point when the assay is performed; or
(c) not mixed during the period of time after the sample is obtained from the subject to the time point when the assay is performed.
14. The method of claim 8 , wherein the UCH-L1 amount in the sample from the subject is assessed as a measure of traumatic brain injury, wherein the subject has sustained or may have sustained an injury to the head.