Antibodies are a very versatile biologic, with utility as therapies and as scientific tools. Antibodies have a long-established utility as diagnostic tools. A good example of antibodies as diagnostic tools is the pregnancy testing kit. The dip-stick in this urine sampling kit make use of a pair of monoclonal antibodies. The protein human chioronic gonadotropin (hCG) is elevated during pregnancy. The elevated levels of hCG can be detected by antibodies. Any hCG present in the urine sample is bound by a gold-colloidal anti-hCG monoclonal antibody (mAb). The gold-mAb-hCG complex travels through the dip-stick by capillary action. A second, immobilised anti-hCG mAb captures the complex as it travels through the kit. If the immobilised complex reaches a threshold concentration it becomes visible as a line within the dip-stick results window; a positive result [1].
In addition to the use of antibodies for the detection of medically relevant antigens, antibodies can be used for the detection of environmental pollutants. Microcystins are toxins produced by the blue-green algae Cyanobacteria and are a cause of water pollution worldwide. Monoclonal antibodies specific to microcystin have been used to improve the detection of toxic levels of the pollutant in water samples [2]. The specificity of monoclonal antibodies can be demonstrated by another antibody that targets an environmental pollutant. Atrazine is an herbicide contaminant of drinking water. Atrazine is a member of the triazine class of pesticides. The potential for monoclonal antibodies to be very specific is demonstrated by an antibody to atrazine that does not recognise any of the other triazine family members [3].
Diagnostic antibody devices also serve an unmet medical need. In 2012 the Food and Drug Agency (FDA) approved an in-home HIV diagnostic kit. Antibodies to HIV present in oral fluid are collected by a swab and detected by buffered test solution of the kit. In this way a qualitative assessment of HIV infection can be determined in the privacy of your own home [4].
Here at Scotia Biologics, one of our current projects is the development of an antibody-based, real-time, point-of-need device for the detection of potentially lethal levels of anaesthetic in patient blood. This use of antibodies as diagnostics will be used to increase patient safety, with particular focus on vulnerable groups of society, such as infants and the older population.
All of these examples highlight the versatility and importance of diagnostic monoclonal antibodies.
References
2. Strachan G., et al., 2002 FEMS Microbiology Letters 210 (2002) 257^261
3. Charlton K., Harris W.J., Porter A.J., (2001). The isolation of super-sensitive anti-hapten antibodies from combinatorial antibody libraries derived from sheep. Biosensors & Bioelectronics 16: 9-12; 639-646