IL-5 production by allergen-stimulated T cells following grass pollen immunotherapy for seasonal allergic rhinitis.
Grass pollen immunotherapy for the treatment of seasonal allergic rhinitis ('summer hayfever') results in improvement in symptoms, a reduction in the early and late phase responses to allergen provocation and decreased tissue eosinophilia. Immunotherapy may act by altering the pattern of cytokine production by allergen-specific T cells from a 'Th2-type' (IL-4 and IL-5) profile to a 'Th1-type' (interferon-gamma (IFN-gamma)) profile. We set out to determine whether clinical improvement following specific allergen immunotherapy is accompanied by reduced production of the pro-eosinophilic and archetypal 'Th2-type' cytokine, IL-5. Peripheral blood mononuclear cells (PBMC) were isolated from (i) 13 patients who had received 6 or 7 years' continuous conventional immunotherapy with timothy grass pollen (Phleum pratense); (ii) 14 patients who had received 3 or 4 years of conventional immunotherapy followed by 3 years of placebo treatment; (iii) 12 matched seasonal rhinitic patients who had never received immunotherapy; and (iv) 17 non-atopic normal controls. PBMC were stimulated with 20 microg/ml and 200 microg/ml P. pratense extract, or 10 microg/ml of Mycobacterium tuberculosis purified protein derivative (PPD), at 2 x 10(6) cells/ml and 5 x 10(6) cells/ml. IL-5 concentrations in culture supernatants collected after 6 days' culture were measured by ELISA. IL-5 production in response to stimulation with P. pratense extract was highly reproducible and was elevated in both of the immunotherapy treated groups and the untreated rhinitics relative to non-atopic controls (P<0.005 for each group relative to non-atopic controls, under each of the four conditions tested). However, no significant reduction was observed in IL-5 production when immunotherapy treated patients were compared with untreated rhinitic controls. Moreover, abrogation of the cutaneous late-phase responses to allergen following treatment was not associated with reduced IL-5 production by allergen-stimulated peripheral blood T cells. Reduced IL-5 production by peripheral blood T cells may not be necessary for immunotherapy to be effective. Local immunodulation of T cell responses may play a role in this form of treatment.
Till
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S
Upper Respiratory Medicine, Imperial College School of Medicine at National Heart and Lung Institute, London, UK.
Walker
S
S
Dickason
R
R
Huston
D
D
O'Brien
F
F
Lamb
J
J
Kay
A B
AB
Corrigan
C
C
Durham
S
S
D000328:Adult; D005260:Female; D006801:Humans; D007167:Immunotherapy; D015848:Interleukin-5 / Q000096:biosynthesis*; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D008517:Phytotherapy; D011058:Pollen / Q000276:immunology* / Q000627:therapeutic use; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology* / Q000628:therapy; D018418:Th2 Cells / Q000276:immunology*
D015848:Interleukin-5