Prostate Specific Antigen (PSA) Test Information   The detection of PSA on forensic samples is often helpful because it confirms the presence of semen even in samples that involve vasectomized or azospermic individuals. PSA is a glycoprotein produced by the prostate gland and secreted in seminal fluid at concentrations ranging from 2.0x105 to 5.5x106 ng/ml.   The PSA  test confirms the presence of semen by utilization of a dye-labeled mobile monoclonal antibody that binds to the PSA.   The PSA antibody complex diffuses horizontally on a membrane with two regions of fixed antibodies. Immobilized polyclonal PSA antibodies are located in a test region and antihuman immunoglobulin antibodies are present in a control region. In these regions, the mobile PSA antibody complex and/or free dye-labeled PSA antibody interact with the immobilized antibody regions.   Following the application of 200 µl of sample extract and a 10 minute diffusion time, the accumulation of the dye labeled antibodies results in the formation of pink bands at the test and control regions. A pink band at the control region signifies that the test was run appropriately. Immobilization of the antigenantibody complex at both the test and control region positively identifies the presence of the PSA.