In article <20021210030856.5919.qmail at ww02.hostica.com>,
drrodriguez at hotmail.com wrote:
> A child has severe hay fever. A total IgE measurement was performed by the
> Ouchterlony immunodiffusion method. No lines of precipitation appeared on
> the immunodiffusion plate. What is the most likely explanation for this
> event?
>>>> so is no precipitation possible? if so, what's going on here? someone,
> anyone?
>> thanks.
>>http://biowww.net/mynews/tree.php?group_name=bionet_immunology&begin=0
Yes, it is entirely possible that precipitation might not occur, if the
amount of antibody greatly exceeds the amount of antigen.
Precipitation is based on antibodies being multivalent and, thus,
crosslinking the antigen until it precipitates. If there is a great
excess of either the antigen or antibody, then the antibody binds to
only one molecule and will remain soluble and not precipitate.
Try doing serial dilutions of the antibody against the antigen to test
this.
Perhaps less likely, there are some situations where allergy is not IgE
dependant. C5a, IL-3 and hypoosmolality can activate mast cells in some
circumstances.
Hope this helps,
Regards,
C. Allen Black, Ph.D.
University of Pittsburgh
