Immunology questions & terminology

Mark Haynes Mark.Haynes at Mail.TJU.Edu
Mon Nov 27 14:17:35 EST 2000


Anostica wrote:

> I'm curious about is why is it that the major
> histocompatibility complex in humans is called Human Leukocyte Antigen

THink of the word antigen as being equal to the word 'thing' as in any THING
can be an antigen--a doorknob is my favorite antigen because it sticks out
from the plane of the door just like the artistic dawings of virus antigens
the stick out from the surface of the virus.  historically, these molecules
were identified by lymphocyte reactions against them and so they got called
antigens that governed tissue compatability.  the prefix histo- means tissue
and so histo-compatibility antigens.

> 2. I know that MHC's (major histocompatibility complex) are a set of genes
> that
> code for White blood cells..

MHC's aren't antibodies so the terms are not interchangababble (sorry gwbush
came out).  Both are proteins that are encoded by genes.  Again, the term
antigen is not that specific a term-it just means a 'thing' that can be
recognized by the immune system.
MHC class I proteins are almost all cells
MHC class II proteins are on cell of the immune system and a couple other
the distribution of the proteins seems to depend upon the function of the
protein--and it really gets complicated to go further--i suggest immunology
text books or on-line info maybe from the american association of
immunologists web site (

and the pig quest ion was answered but I would also say that anti-rejection
drugs may be part of the answer

> I was asked about why pig heart valves can be transplanted into
> humans. The only answer I could come up with is because we may not or do
> not have any white blood cells there that can scavenge around the area
> and check for antigens. I thought that since that area is constantly
> being flushed by blood, it may cause that area to be somewhat out of
> reach by the immune system.
> that's it..thank you for your time..
> -Jane

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