The Effect Of Pulmonary Surfactant On The Activation Of T Lymphocytes During An Asthma Attack

Objective: To study the effect of pulmonary surfactant (PS) on the activation of T lymphocytes during an asthma attack by animal and clinical experiments. Methods: (1) Eighty SD rats were randomly divided into four groups: the normal control group, the model group, the PS group and the NS (normal saline) group, 20 rats in each group. Except for the normal control group, other groups were sensitized with ovalbumin (OVA) by a combination of intraperitoneal injection and repeated aerosol inhalation to establish the rat asthma model. The experiment was divided into two parts. The first part is to assess the change in vivo when PS was directly delivered into the airway of asthma model. Spleen cells, BALF and lung tissues were collected. The proliferating rate of lymphocytes, BALF total cell numbers and differentials were determined. The effect of PS on the pulmonary pathology was also studied. The second part is to assess the change of lymphocytes proliferation in vitro when the spleen lymphocytes of asthma model were incubated with a varying concentration of PS. (2) The lymphocytes samples were obtained from peripheral blood of 40 patients during an acute asthmatic attack. They were incubated with PS and divided into two groups. One group was to assess the change of CD69 expression on T cells by means of flow cytometry (FCM). The other group was also analyzed by FCM to study the effect of PS on T cell subsets (Th1 and Th2). Results: (1 )The manifestation of rats during an acute asthmatic attack, the change of BALF total cell numbers, differentials, and the pulmonary pathology all indicate that the rat asthma model was successfully established. (2) The proliferating rate of model group was significantly higher compared with that in normal control group, however the rate of PS group was significantly lower than that in model group. (3) In vitro the number of T lymphocytes incubated with PS wasdecreased by increasing the concentrations of PS. (4) The clinical tests showedthat the CD69 expression on T lymphocytes from the acute asthmatic patients wasinhibited by PS, while the ratio between Th1/Th2 subsets was significantlyenhanced.Conclusions: During an asthmatic attack, PS can inhibit the activation andproliferation of T lymphocytes by inhibiting CD69 expression on T cells, and theratio between Th1/Th2 subsets was significantly increased. These data indicate that PScan suppress airway inflammation in asthma by inhibiting the activation of Tlymphocytes.