THE ATTENUATIVE EFFECT OF PURIFIED PROTEIN DERIVATIVE SENSITIZATION ON T-HELPER-2 REACTION AND EOSINOPHIL INFILTRATION OF THE LUNG IN OVALBUMIN SENSITIZED MICE

Objectives To identify the effects of tuberculin purified protein deri vative (PPD) sensitization on attenuating pulmonary T helper 2 (Th2) r eaction and eosinophil infiltration in ovalbumin sensitized mice, and to search for the possibility of its clinical use in the management of asthma in a new way. Methods Sixty C57BL/6 mice were sensitized with PPD and then with ovalbumin and aluminum hydroxide, and randomized int o 4 groups: ovalbumin (OVA), pre-PPD, post-PPD and control groups. Aer osol PPD were administered 3 h before or after ovalbumin challenge in the pre-PPD and post-PPD groups respectively, and control group receiv ed aerosol PPD only. IL-4, IL-5 expression was detected by immunocytoc hemistry in situ hybridization. Lung slides were stained with eosin an d hemotoxylin, and pathological changes were observed. Results Ovalbum in aerosol inhalation caused a mixed inflammatory infiltration dominat ed by CD4(+) T lymphocytes and eosinophils in the lung of sensitized m ice. 87.5% - 89.7% and 89.0% - 89.2% of the CD4(+) T lymphocytes were IL-4 mRNA(+) and IL-5 mRNA(+) respectively. 88.7% - 91.2% of IL-4 mRNA (+) cells and 89.8% - 90.6% of IL-5 mRNA(+) cells were CD4(+) T lympho cytes in OVA group. Aerosol administration of PPD markedly suppressed IL-4 and IL-5 expression, and lung eosinophil infiltration. It was mor e effective in pre-PPD group. 76.6% - 78.0% of IL-4 mRNA(+) and 73.8% - 79.7% of IL-5 mRNA(+) cells were CD4+ and 78.1% - 84.9% and 78.4% - 85.3% of the CD4+ cells were IL-4 mRNA+ or IL-5 mRNA(+) respectively i n pre-PPD group, both were markedly lower than that of OVA group. CD4( +) percentage of IL-4 mRNA+ and IL-5 mRNA(+) cells were 80.7% - 82.0% and 78.0% - 83.9% in post-PPD group, which were markedly lower than th at of OVA group. Conclusions Sensitization with PPD by intraperitoneal injection and then challenged by PPD inhalation markedly suppressed I L-4, IL-5 expression and eosinophil infiltration, and attenuated pulmo nary Th2 reaction in ovalbumin sensitized mice. This induces Th1 type reaction and inhibits Th2 cell differentiation. It may be beneficial f or glucocorticoids dependent or resistant patients.