Objective: To explore whether regulatory CD(4)(+)CD(25)(+) cells exist in patients with atopic asthma.
Methods: The numbers of peripheral blood CD(4)(+)CD(25)(+) cells in peripheral blood of atopic asthmatics and healthy nonatopic subjects were determined using flow cytometry. CD(4)(+)CD(25)(+) and CD(4)(+)CD(25)(-) cells from atopic asthmatics and normal donors were isolated, and were cultured to observe the effects of CD(4)(+)CD(25)(+) cells on proliferation response as well as Th1/Th2 cytokine production of CD(4)(+)CD(25)(-) cells in vitro.
Results: A significant increase in CD(4)(+)CD(25)(+) cell numbers was shown in atopic asthmatic patients during acute exacerbation [(14.9 +/- 1.8)%, P < 0.01], but not in patients with stable asthma [(11.8 +/- 0.7)%] and normal subjects [(11.2 +/- 0.8)%, P > 0.05]. The mean inhibition values of the proliferation response of CD(4)(+)CD(25)(-) cells by CD(4)(+)CD(25)(+) cells from normal controls [(72 +/- 8)%] and asthmatics [(74 +/- 9)%] were similar (P > 0.05). There was no difference in inhibitory effects on both Th1 and Th2 cytokine production of CD(4)(+)CD(25)(-) cells by CD(4)(+)CD(25)(+) cells in the two groups.
Conclusion: Although CD(4)(+)CD(25)(+) cells increase in atopic asthma during exacerbation, these regulatory T cells appear to function normally with regard to their suppressive activities.