This is a tangent on eosinophilia...
As a type 1 hypersensitive individual (i.e., if it flies in the air, I'm
allergic to it), I have found intriguing the hypothesis that
allergies are an abnormal manifestation of an arm of the immune
response that ought to be responding to parasites (presumably helminth).
My understanding of the notion is that:
a) there is no logical rationale for human evolution to have selected
an arm of the immune response to generate allergies.
b) many of the same systems used in fighting off parasites are active
in allergic responses (e.g., eosinophilia, mast cells, prostaglandin
c) that allergies are more prevalent (both phenotypically and in
terms of HLA haplotype predispositions) in caucasian populations
which may be a result of the long history of a hyper-hygenic
environment for this "group".
Anyway... does anyone know if this has gone any further than mere
speculation? I mean it's an interesting hypothesis but it sounds like
it's only that and is as yet empirically empty.
I wonder if a few bouts of toxocariasis when I was a kid would have
saved me the miseries of August as an adult? :-)
Mark E. Siddall "I don't mind a parasite...
mes at vims.edu I object to a cut-rate one"
Virginia Inst. Marine Sci. - Rick
Gloucester Point, VA, 23062