Chemokines and Parasites?
I want to write to see if anyone has any thoughts on a possible interaction
between chemokines (intercrines; such as IL-8, MIP-1alpha/beta, RANTES
etc.) and the coat of parasites. The chemokine family of cytokines are
characterised both on structural terms and on their ability to bind to
heparin (a property shared by some other molecules such bFGF). A major role
of these molecules is mediation of chemotaxis and adherence. Recently it
has been shown that the binding of such molecules to the proteoglycan on
endothelial cell surface is probably important in providing surface bound
chemotactic (or haptotatic) and localisation signals (See papers by Stephen
Shaw's group; Nature 361, 79, Immunol Today 14, 111 and by Rot; EJI 23 303,
Immunol Today 13 291).
A second role of chemokines, however, is to induce cytotoxic mechanisms.
For example IL-8, MIP-1alpha/beta can induce neutrophils to degranulate,
releasing lysosomal enzymes and to produce reactive oxygen species. This
has led me to propose in a cheeky letter to Immunol Today (15, 88) that
chemokines might bind to the surface carbohydrate residues of bacteria,
both helping to trigger leukocyte cytotoxic mechanisms and possibly to
provide opsonin like signals. I have no direct evidence for this, but it
seems a reasonable idea. The polysaccharides on the surface of some
bacteria resemble those seen in proteoglycans, indeed one bacteria has a
capsule identical in sequence to heparin.
I know next to nothing about parasites. However I was recently looking
through an issue of Parasitology Today and came across an article about the
coats of nematodes (8 243). It suggested that the outer coat of nematodes
contains proteoglycan like structures. Could a similar mechanism act in
immunity to parasites? Alternatively could parasites use a disposable coat
that can bind and mop up chemokines as part of their defence against an
immune response? Any ideas or thoughts on this subject would be most
welcome!
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Andrew J.T. George
Department of Immunology
Royal Postgraduate Medical School
Hammersmith Hospital
Du Cane Road
London W12 0NN
Tel 081 743 2030 ext 2089 From overseas +44 81 743 2030 ext 2089
Fax 081 749 8034 +44 81 749 8034
Email: JANET ajgeorge at uk.ac.rpms
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