THIS RESPONSE HAS ALSO BEEN POSTED ON THE PEBL SITE WHICH IS DEDICATED TO TALK ABOUT HIV SELF TESTING. VISIT:-  http://peblfeedback.com/hivselftest/   Hi Boogy Man Thanks for getting in touch with us. The control line is triggered by a protein that all people have in their blood it is not an antibody as such, but is a universal blood product. So you can only get a valid result if you have applied enough blood to the device to trigger this line. The filter has holes that are big enough to let all antibodies through but not big enough to let whole blood cells through for example. The filter does not affect the result of a test. I hope that this answers your questions. If you need any information please don't hesitate to get in touch. Kind regards Gary Carpenter BioSure (UK) Limited   THIS RESPONSE HAS ALSO BEEN POSTED ON THE PEBL SITE WHICH IS DEDICATED TO TALK ABOUT HIV SELF TESTING. VISIT:-  http://peblfeedback.com/hivselftest/