Book:The Comprehensive Guide to Physician Office Laboratory Setup and Operation/Primary laboratory testing domains in the POL/Immunology

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2.4 Immunology

ID Now testing (51038387158).jpg

In December 2014, healthcare market research company Kalorama Information estimated that by volume, several immunological tests ranked in the top 10 tests conducted in POLs. Kalorama ranked the rapid antigen detection test for group A streptococcus and the human Chorionic Gonadotropin (hCG) urine pregnancy test fifth and eighth respectively in physician office use.[1] The popularity of these two immunological tests, among others, in the POL is likely due to their availability as inexpensive qualitative CLIA-waived tests. This is exemplified by CLIA-waived over-the-counter products like Proctor and Gamble's Clearblue PLUS Pregnancy Test, which can be bought for less than $10 U.S. and provide a qualitative result in three minutes.[2] And CLIA-waived Strep A test kits that provide a result in five minutes can by bought with multiple tests per box, working out in some cases to less than $2 U.S. per test.[3] In addition to these types of tests, a handful of other CLIA-waived immunological tests are available to POLs (detailed in the testing subsection).

2.4.1 Basic concepts and collection procedures

The human body's immune system is largely responsible for defending against a wide variety of foreign entities, including microorganisms and allergens among others. When these enter or appear in the body, the immune system must determine what belongs and what doesn't belong. The foreign substance, often referred to as an antigen, is met with a wave of antibodies designed to attach to and destroy it. Additionally, the antibodies are tasked with "remembering" its encounter with the antigen so the antibody can be more agile the next time it is confronted with the foreign body. Usually this process works as intended, but in some cases the body's ability to identify properly goes wrong, and the immune system rebels against useful constituents of the body. As laboratory science has progressed, we've created new and novel ways to search for antigens, antibodies, and attacks against the "self" by applying various in vivo and in vitro tests to various body fluids.[4][5]

The most common body fluids used in immunological testing are blood, serum, urine, and oral fluids, though occasionally body tissues may need to be examined. As such, the collection procedures used for these fluids will be the same as in urinalysis, hematology, and clinical chemistry. In complex cases—likely not conducted in a POL—body tissues such as placenta[6], mucosa-associated lymphoid[7], and even bone marrow[8] may need to be collected for immunological analysis, requiring special surgical techniques.

2.4.2 Specimen composition and testing

Several testing methodologies are used in immunological testing; however, for CLIA-waived testing the most common methodology is lateral flow immunoassay. Practically speaking, this means a specimen is absorbed by the testing device, flowing laterally over the testing materials to reach the antigen or antibody contained within the testing materials. Color changes can be matched to a key to indicate a positive or negative qualitative change.[4] Lateral flow testing has many advantages as well as a few disadvantages. The technology is relatively cheap, easy-to-use, quick, versatile, easy to commercialize, and testing devices typically maintain a long shelf life. However, they also tend to only give qualitative results, manufactured lots can vary in quality (with reagents used), and test accuracy may suffer from cross-reactivity.[9] Most recently, with the COVID-19 pandemic, this type of antigen lateral flow immunoassay technology has been put to use (via emergency use authorization) in testing options like Abbott's BinaxNOW COVID-19 Antigen Self Test.[10]

Earlier we mentioned pregnancy and group A strep tests as examples of immunology-based tests that are often CLIA-waived. These and other examples—by disease, condition, or analyte—include[5][4][11]:

  • eye disorders: Either 1. testing for adenoviral conjunctivitis (Ad-CS, an affliction commonly known as pink eye) via examination of eye fluid or 2. or the inflammatory marker MMP-9 (associated with dry eye disease) found in tear fluid
  • fertility: Detection of luteinizing hormone (LH) in urine
  • gastric disorders: Either 1. testing for the H. pylori bacterium (found in the stomach) via examination of whole blood (or in some cases serum or plasma) or 2. gastric occult blood in gastric aspirates or vomitus by directing antibodies against human hemoglobin that might be present
  • hepatitis C: Testing for the presence of the hepatitis C virus antibody via fingerstick or whole blood
  • HIV-1 and -2 infection: Testing for the presence of the human immunodeficiency virus (HIV) in blood
  • influenza: Detection of the influenza type A and type B antigens via nasal or nasopharyngeal swabs
  • intestinal disorders: Testing for fecal occult blood in the stool by directing antibodies against human hemoglobin that might be in the stool
  • menopause: Detection of the follicle-stimulating hormone (FSH) in urine
  • mononucleosis: Testing for the presence of infectious mono heterophile antibodies in whole blood (or in some cases serum or plasma)
  • pregnancy: Detection of the hormone human chorionic gonadotropin (hCG) in urine
  • respiratory syncytial virus: Testing for the presence of the respiratory syncytial virus (RSV) via nasal secretions
  • strep throat: Detection of the group A streptococcal antigen, typically from a throat swab
  • syphilis: Detection of Treponema pallidum (syphilis) antibodies in fingerstick blood (or in some cases whole blood, serum, or plasma)
  • trichomoniasis: Testing for the presence of Trichomonas vaginalis antigens via vaginal swabs
  • urinary disorders: Detection of the bladder tumor associated antigen (BTA) in urine

CLIA-waived instruments that can perform multiple qualitative immunological tests are somewhat limited. Abbot's ID NOW is currently CLIA-waived for influenza A and B, group A strep, and RSV.[12][13] Becton, Dickson and Company offers their Veritor System, which is also CLIA-waived for influenza A and B, group A strep, and RSV.[14]

You can find an extensive listing of CLIA-waived POL instrument and test kit vendors (including for the immunological analytes mentioned above) in the Additional Resources section of this guide.

References

  1. ↑ "Top 10 Tests In Physician Office Revealed". Kalorama Information. 10 December 2014. Archived from the original on 05 June 2015. https://web.archive.org/web/20150605181846/http://www.kaloramainformation.com/about/release.asp?id=3686. Retrieved 13 May 2022. 
  2. ↑ "Clearblue PLUS Pregnancy Test". Clearblue. Proctor & Gamble. https://www.clearblue.com/pregnancy-tests/rapid-detection. Retrieved 13 May 2022. 
  3. ↑ "ACCUSTRIP Strep A Value+ Test Strip (CLIA-Waived)". Accutest. JANT Pharmacal Corporation. http://www.accutest.net/products/id413.php. Retrieved 13 May 2022. 
  4. ↑ 4.0 4.1 4.2 Lieseke, Constance L.; Zeibig, Elizabeth A. (2012). Essentials Of Medical Laboratory Practice. F. A. Davis. pp. 539. ISBN 9780803630352. https://books.google.com/books?id=IX_2AAAAQBAJ&pg=PA1. Retrieved 13 May 2022. 
  5. ↑ 5.0 5.1 Garrels, Marti; Oatis, Carol S. (2014). Laboratory and Diagnostic Testing in Ambulatory Care: A Guide for Healthcare Professionals (3rd ed.). Elsevier Health Sciences. pp. 368. ISBN 9780323292368. https://books.google.com/books?id=LM9sBQAAQBAJ. Retrieved 13 May 2022. 
  6. ↑ Othoro, Caroline; Moore, Julie M.; Wannemuehler, Kathleen; Nahlen, Bernard L.; Otieno, Juliana ; Slutsker, Laurence; Lal, Altaf A.; Shi, Ya Ping (2006). "Evaluation of Various Methods of Maternal Placental Blood Collection for Immunology Studies". Clinical and Vaccine Immunology 13 (5): 568–574. doi:10.1128/CVI.13.5.568-574.2006. PMC PMC1459646. PMID 16682478. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1459646. 
  7. ↑ Shacklett, Barbara L.; Critchfield, J. William; Lemongello, Donna (2009). "Isolating Mucosal Lymphocytes from Biopsy Tissue for Cellular Immunology Assays". Methods in Molecular Biology 485: 347-56. doi:10.1007/978-1-59745-170-3_23. PMID 19020836. 
  8. ↑ Zhao, Ende; Xu, Huanbin; Wang, Lin; Kryczek, Ilona; Wu, Ke; Hu, Yu; Wang, Guobin; Zou, Weiping (2011). "Bone marrow and the control of immunity". Cellular & Molecular Immunology 9: 11-19. doi:10.1038/cmi.2011.47. PMC PMC3251706. PMID 22020068. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3251706. 
  9. ↑ Sajida, Muhammad; Kawdea, Abdel-Nasser; Daud, Muhammad (2014). "Designs, formats and applications of lateral flow assay: A literature review". Journal of Saudi Chemical Society. doi:10.1016/j.jscs.2014.09.001. 
  10. ↑ Abbott (31 March 2021). "Abbott's BinaxNOW Rapid Antigen Self Test Receives FDA Emergency Use Authorization for Asymptomatic, Over-the-Counter, Non-Prescription, Multi-Test Use". PR Newswire. https://www.prnewswire.com/news-releases/abbotts-binaxnow-rapid-antigen-self-test-receives-fda-emergency-use-authorization-for-asymptomatic-over-the-counter-non-prescription-multi-test-use-301260240.html. Retrieved 17 May 2022. 
  11. ↑ "CLIA - Clinical Laboratory Improvement Amendments - Currently Waived Analytes". U.S. Food and Drug Administration. 9 May 2022. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfClia/analyteswaived.cfm. Retrieved 13 May 2022. 
  12. ↑ Seiffert, Don (12 January 2015). "FDA waiver of Alere's flu test poses threat to market leader Cepheid". Boston Business Journal. American City Business Journals. https://www.bizjournals.com/boston/blog/bioflash/2015/01/fda-waiver-of-aleres-flu-test-poses-threat-to.html. Retrieved 13 May 2022. 
  13. ↑ "ID NOW". Abbott. https://www.globalpointofcare.abbott/en/product-details/id-now.html. Retrieved 13 May 2022. 
  14. ↑ "BD Veritor System". Becton, Dickson and Company. https://bdveritor.bd.com/en-us. Retrieved 13 May 2022. 
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