Smooth Muscle Antigen - Research Paper Example

Smooth Muscle Antigen Principles & Application The human muscular system consists of three types of muscles – skeletal, smooth and cardiac. Skeletal muscles control every action that a person consciously performs such as standing, walking, sitting, talking, and eating. Smooth or visceral muscle is found inside hollow organs such as the stomach, the gastrointestinal tract, the lungs, blood vessels, the bladder or the uterus. These muscles contract to move and digest food, absorb nutrients and expel waste from the system. These muscles are controlled by the unconscious part of the brain, unlike the skeletal muscles. The name smooth muscle comes from the fact that these muscles do not have the banded appearance of skeletal or cardiac muscles. The third group is the cardiac muscles that serve to pump blood through the human body. Cardiac muscles, like the smooth muscles, are controlled involuntarily (Zimmermann, 2014). Several forms disease could affect smooth muscles as shown in the charts below (Elgaddar, 2013). When antigens such as bacteria or viruses attack smooth muscle, the body’s immune system produces antibodies to counter the antigen. Every antibody produced is unique, to defend against one type of antigen. In rare cases, antibodies are produced to attack the body’s own healthy cells. These are called auto antibodies and the person has an autoimmune disorder (Blocka, 2012). Fig 1.1 – Smooth muscle diseases (Elgaddar, 2013). The most common smooth muscle disease is hepatitis or inflammation of the lever. Hepatitis types A and B are usually self-limiting. Most cases that require clinical studies are of hepatitis C. When a physician diagnoses smooth muscle problems, the first test he recommends is a test for hepatitis. The hepatitis virus itself cannot be detected in a test. When the virus is present, the human system produces antibodies which can be identified and serve as an indicator for presence of the infection. The Anti-Smooth Muscle Antibody or ASMA test is performed on a blood sample drawn from a vein in the arm of the person (Blocka, 2012). Smooth muscle antibodies were first identified in patients with chronic hepatitis, other liver diseases, viral infections, certain cancers and female infertility. SMA is a heterogeneous group of antibodies reactive with different smooth muscle auto antigens. Different SMAs give different immunofluorescent staining patterns which help the laboratory to identify the SMA (Toh, 1979). 2. Selection & Interpretation of Controls The history of the person for whom ASMA test is being administered is of relevance in the conduct of tests and interpretation of results. Hepatitis C is often associated with intravenous drug use and the sharing of needles and syringes. The infection may also be caused by a tattoo created using non-sterile needles. If the person received a blood transfusion prior to 1992 when blood donors were not screened for the virus, the risk of hepatitis C infection is higher. Healthcare workers exposed to blood from patients or donors may also be at higher risk (Roland, 2014). The blood test first checks for the presence of HCV antibodies. If no HCV anti-bodies are found, no further tests are indicated. If the test result is “HCV antibody reactive”, a second test to check for HCV ribonucleic acid (RNA) is done. If RNA is detected, the person is infected with Hepatitis C virus. If RNA is not detected, the first test is considered a “false positive” and a repeat test may be done to eliminate doubt (Roland, 2014). The HCV anti-body detection is by Enzyme Immunoassay (EIA). The third generation tests now in use are more sensitive and specific than previous ones. However, false-positive results are occasionally a problem. The HCV- RNA test uses a sensitive polymerase chain reaction (PCR) assay. The RNA test is particularly helpful in patients with low immune levels who may not produce enough anti-bodies to be detected in the EIA test. 3. What should be seen in a well stained slide The EIA blood test would only establish the presence of antibodies against the HCV virus in the blood stream. The comparison is with a control sample which is known to be non-infected. Laboratories for EIA blood screening are required to use only FDA-approved or licensed screening kits. These immunoassay kits use HCV-encoded recombinant antigens. Criteria for interpretation of test results are based on clinical studies conducted by each manufacturer of the test kit. Any test result that is positive of HCV infection is retested for confirmation before the results are communicated to the patient. This is to prevent unnecessary medical visits and psychological harm to the patient (Alter, et al, 2003). 4. Problem causes in the test process and solutions The EIA test does not distinguish between acute, active or resolved infection. A patient who has had a hepatitis infection carries antibodies for life. This could result in a “false positive” test result. Understanding the clinical background of the patient could help eliminate some of these cases. The test is also not effective in the time period between exposure and seroconversion, which is typically 8 weeks. When the patient background indicates possibility of insufficient time period between exposure and test, repeat testing may be indicated when the test report is negative. Patients with immune deficiency disorders have reduced ability to produce antibodies. Tests on such patients may also be “false negative” (Wisconsin DHS). The EIA test may also show “false positive” results due to other antigens in the system. For example, people living in countries or regions which have high incidence of infectious diseases may have higher chances of “false positive” EIA results (Wisconsin DHS). Correlation of patient profile with the test is important to eliminate the need for additional tests. 5. Safety and Precautions The laboratory conducting tests on blood samples should comply with the OSHA safety standard relating to blood borne pathogens. The standard points out that blood borne pathogens can cause diseases such as hepatitis B, hepatitis C and human immunodeficiency virus (HIV). The specific steps include (OSHA, n.d.) i. Engineering and work practice controls for safe handling of blood samples ii. Use of personal protective clothing and equipment such as aprons, gloves, masks and eye glasses iii. Training to employees and display of warning signs and notices iv. Medical surveillance of people v. Preventive vaccination such as for hepatitis B. ************ References: Alter, M.J., Kuhnert, W.L. and Finelli, L. (2003). “Guidelines for Laboratory Testing and Result Reporting of Antibody to Hepatitis C Virus”, Center for Disease Control and Prevention, January 27, 2003. Retrieved on June 3, 2015 from Blocka, K., (2012). “Anti-Smooth Muscle Antibody”, Health line, August 15, 2012. Retrieved on June 2, 2015 from Elgaddar, O., (2013). “Laboratory diagnosis of muscle diseases”, Health & Medicine, October 18, 2013. Retrieved on June 2, 2015 from HepCNet, (2003). “Hepatitis C Tests”, HepCNet, March 7, 2003. Retrieved on June 2, 2015 from OSHA, (n.d.). “Blood borne Pathogens and Needle stick Prevention”, Occupational Safety & Health Administration. Retrieved on June 3, 2015 from Roland, J., (2014). “What to Expect from a Hepatitis C Blood Test”, Health line, April 18, 2014. Retrieved on June 2, 2015 from Toh, B.H., (1979). “Smooth muscle auto antibodies and auto antigens”, Clinical & Experimental Immunology (1979), 38, 621-628. Retrieved on June 2, 2015 from Wisconsin DHS, (2011). “Interpretation of Hepatitis C Test results”, Wisconsin Department of Health Services, summer 2011. Retrieved on June 3, 2015 from Zimmermann, K.A., (2014). “Muscular Systems: Facts, Functions & Diseases”, Live Science, November 25, 2014. Retrieved on June 2, 2015 from Read More