question about penicillin allergy - (Feb/13/2008 )
hello
i just had an argument with a coworker. i hope you immunology experts can settle this. 
is penicillin allergy a REAL allergy or a pseudo allergy/intolerance?
of course i allready looked that up in books and the internet but i allways found the two contradicting statements that
1) a real allergy can only be caused by antigens with at least 1000 daltons.
2) surprisingly penicillin allergy is considered to be a real allergy allthough penicillin has merely about 300 daltons and therefore shouldnt be immunogenic at all
hope you can help me
regards
Given that penicillin can cause anaphylaxis in some, I would lean towards the allergy side. I don't know that much about allergens, but I have done a little reading on the topic as I am actually allergic myself. Interesting argument that must have been, however 
I think you will find that no matter what the "rule" in science, there will always be exceptions- as the "rules" are made up by scientists and can sometimes be wrong
Penicillin allergy is for REAL. One can die from penicillin allergy.
Doctors have to test for penicillin allergy before administering it to patients.
i think that the 1000 dalton rule is a general rule for antibody production. this is defeated by sensitizing the immune system and/or artificially increasing the size of the antigen.
but it is a general rule, not hard and fast.
Isn't it because of Penicillin binding to some hapten?
Have to look that up now but that is what I thought till now.
Ok. . . with googling I found this
''Penicillin is a chemical hapten with a low molecular weight of 300 d that needs to bind to a tissue macromolecule, usually a protein, to become immunogenic.7 The breakdown products of penicillin include the penicilloyl group, known as the major determinant because it is the major penicillin metabolic product (approximately 85% to 90% of the penicillin breakdown products).7 The minor haptenic determinants or minor determinant mixture, so called because they are formed in smaller quantities,7 are composed of the parent penicillin molecules, penicilloate, penicilloylamine, penilloate, and other simple chemical products of penicillin.7 Immediate reactions following penicillin administration are mediated through IgE antibodies against either the major or minor determinants, or both.''
Reference is : Erffmeyer JE, Blaiss MS. Proving penicillin allergy. Postgrad Med. 1990 Feb 1;87(2):33-5, 39, 41. (I do not have access to it)
Hmm, this thing is interesting : Weltzien HU, Padovan E. Molecular Features of Penicillin Allergy. 1998 Mar ;110(3):203-206.
@scolix:
when i asked if penicillin allergy is real i did not doubt that some people have these allergic reactions (that can even be lethal).
its just that the word "allergy" is so often falsly used in popular and pseudo science. even real doctors mess this up! one told my mother that she was "allergic to mono sodium glutamate" for instance! such nonsense!
first of all glutamate can not cause an immune response. just think that it is a part of virtually every protein in the human body! again i do not doubt that the notorious "chinese restaurant syndrome" does exist. but it definitly isnt an allergy.
you will also often find lactose intolerance referred to as lactose allergy or aquagenic pruritus as water allergy for example.
thats why i asked.
@bungalow boy:
hm that would make sense. i know that mycotoxin-binding antibodies are produced by covalently binding them to immunogenic proteins. and penicillin is sort of a mycotoxin itself at the end of the day.
its just interesting that such a binding can happen all by itself when penicillin is administered to you!
thanks to all for answering
I am not quite sure if U can accuse doctors messing that up. It is easier to explain patients that way. 'Intolerance' might not be understood well by patients.
And about allergy, what I was taught (may be falsely) was - one can have allergy to anything under the sun and even the sun. We even have allergy to ourself in autoimmunity, don't we?
Then we have terms 'heat allergy', 'cold allergy', 'psychogenic allergy' , don' t we?
It cannot be said messing up but same word can have different meaning in common use though not scientific.
you are right. the term allergy is better known than intolerance. and maybe some doctors use the incorrect term when talking to their patients. but even if the word lactose intolerance is not widely known it can be explained to anyone briefly.
dont you think that you as a patient have the right to know exactly whats going on in your body? for example when i called in sick last week and went to a doctor he said that i was suffering from a flu caused by a bacterial infection. i sort of felt cheated because i know that flu is caused by RNA viruses.