MadSci Network: Immunology
Query:

Re: Why is cocaine not immunogenic?

Date: Sun Jun 20 11:31:21 1999
Posted By: Mitchell Ho, PhD Student, Microbiology & Immunology, University of Illinois at Urbana-Champaign
Area of science: Immunology
ID: 929217811.Im
Message:

This is a very good question. Although any structure such as cocaine can be 
recognized by antibody as an antigen, usually only proteins can elicit 
fully developed adaptive immune responses because of their ability to 
engage the T cells. T cells can induce most antibody responses and are 
required for immunological memory. T cells recognize antigens as peptide 
fragments of proteins bound to major histocompatibility complex (MHC) 
molecules. The larger and more complex a protein, the more likely it is to 
elicit an immune response. Some small soluble proteins are unable to induce 
a response unless they are made to aggregate in some way. Cocaine is not a 
protein, and it is a very small and "simple" molecule. Therefore, it 
usually does not elicit an immune response.  However, it can be attached 
covalently to a protein carrier such as keyhole limpet hemocyanin (KLH). 
The cocaine-KLH conjugate can be used to induce the antibodies that 
recognize cocaine.

In your question, you also mentioned the exposure of nasal mucous membranes 
to cocaine and allergic responses. Allergens are antigens that commonly 
provoke an IgE antibody response. For the same reason, usually allergens 
must be proteins because only proteins induce T-cell responses. Thus, 
cocaine can not invoke an allergic reaction. Most allergens are soluble 
proteins that are inhaled in desiccated particles such as pollen grains. 
Your question is interesting because recently scientists are developing 
some vaccines that can be administered to the mucosa by nasal inhalation 
for respiratory infectious diseases. Maybe we can consider using a similar 
structure of cocaine (so-called "molecular mimicry") conjugated with an 
appropriate carrier protein for a nasal vaccine design!




Current Queue | Current Queue for Immunology | Immunology archives

Try the links in the MadSci Library for more information on Immunology.



MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci


MadSci Network, webadmin@www.madsci.org
© 1995-1999. All rights reserved.