Mite-specific induction of interleukin-2 receptor on T lymphocytes from children with mite-sensitive asthma: Modified immune response with immunotherapy

Background: The efficacy of immunotherapy is still controversial. To elucidate the mechanisms of immunotherapy, we studied mite-specific induction of IL-2 receptor (IL-2R) expression on T lymphocytes from children with mite-sensitive asthma. Methods: Peripheral blood mononuclear cells were obtained from 28 children with mite-sensitive asthma: 13 had never received house dust immunotherapy (nonimmunotherapy group), 15 had been receiving house dust immunotherapy at the time of the study (immunotherapy group). After a 6-day culture with or without Dermatophagoides farinae (Df) antigen, the expression of IL-2Rp55 (CD25) and p75 on CD4(+) or CD8(+) T lymphocytes was measured by flow cytometry. Results: The nonimmunotherapy group showed significant Df-specific CD25 induction on CD4(+) T lymphocytes (Delta CD4(+) CD25(+)) but little induction on CD8(+) T lymphocytes (Delta CD8(+) CD25(+)). Delta CD4(+) CD25(+) was correlated with the severity of the disease. In the immunotherapy group Delta CD8(+) CD25(+) was significantly higher than in the nonimmunotherapy group or in normal subjects and correlated with Df-specific IgG(4) and cumulative doses of house dust extract, whereas Delta CD4(+) CD25(+) was similar in the nonimmunotherapy and the immunotherapy groups. IL-2Rp75 was not induced either on CD4(+) or CD8(+) T lymphocytes. Conclusions: Our data suggest that house dust immunotherapy may have induced Df-specific CD8(+) T lymphocytes in patients with mite-sensitive asthma and that the efficacy of immunotherapy may be attributed to the generation of Df-specific CD8(+) T lymphocytes.