Modified T-cell activation pattern during specific immunotherapy (SIT) in cat-allergic patients

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The aim of the study was to analyse early effects of specific immunotherapy (SIT) on immune functions in cat-allergic patients.


Immunological responses of peripheral blood mononuclear cells from eight cat-allergic patients were analysed before and after SIT in comparison with 11 nonallergic controls. Cells were stimulated in vitro with either bacterial superantigen, mitogen, or cat allergen. Production of IL-12 and TH1/TH2 cytokines was analysed by ELISA and lymphocyte subset distribution was assessed by flow-cytometry.


We found a significantly reduced secretion of IL-12 (P < 0.05) from cells of allergic individuals compared with the controls. This finding was associated with significantly lower IFN-γ production after stimulation with allergen (P < 0.05) that did not increase during SIT. However, no significant differences were seen after stimulation with mitogen indicating an allergen specific IFN-γ secretion response in allergic individuals. Prior to SIT IL-5 production was significantly higher in cells of allergic donors stimulated with allergen <0.005 or mitogen (<0.05). After reaching the maintenance dose for SIT, allergen-induced IL-5 production returned to normal levels, whereas it remained elevated after stimulation with mitogen. These changes were associated with a reduced frequency of CD45 RO T cells following SIT.


These results suggest that SIT exerts early effects on allergen-specific T-cell responses with selective inhibition of the up-regulated TH2 immune response.

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