Asthma.

The relation between lower respiratory tract illnesses in early life caused by the respiratory syncytial virus (RSV) and the subsequent development of wheezing and atopy in childhood is not well understood. We studied this relation in children who had lower respiratory tract illnesses that occurred before 3 years of age. Children were enrolled at birth and cases of lower respiratory tract illness were ascertained by a physician. Viral tests were done for specimens collected at the time of the illness. Children were classified into five groups according to type and cause of lower respiratory tract illness. Children were then followed prospectively up to age 13, and we measured frequency of wheezing, pulmonary function, and atopic status (allergy skin-prick tests, serum IgE concentrations). RSV lower respiratory tract illnesses were associated with an increased risk of infrequent wheeze (odds ratio 3.2 [95% CI 2.0-5.0], p < 0.001), and an increased risk of frequent wheeze (4.3 [2.2-8.7], p < or = 0.001) by age 6. Risk decreased markedly with age and was not significant by age 13. There was no association between RSV lower respiratory tract illnesses and subsequent atopic status. RSV lower respiratory tract illnesses were associated with significantly lower measurements of forced expiratory volume (2.11 [2.05-2.15], p < or = 0.001) when compared with those of children with no lower respiratory tract illnesses, but there was no difference in forced expiratory volume after inhalation of salbutamol. RSV lower respiratory tract illnesses in early childhood are an independent risk factor for the subsequent development of wheezing up to age 11 years but not at age 13. This association is not caused by an increased risk of allergic sensitisation.

In atopic asthma, activated T helper lymphocytes are present in bronchial-biopsy specimens and bronchoalveolar-lavage (BAL) fluid, and their production of cytokines may be important in the pathogenesis of this disorder. Different patterns of cytokine release are characteristic of certain subgroups of T helper cells, termed TH1 and TH2, the former mediating delayed-type hypersensitivity and the latter mediating IgE synthesis and eosinophilia. The pattern of cytokine production in atopic asthma is unknown. We assessed cells obtained by BAL in subjects with mild atopic asthma and in normal control subjects for the expression of messenger RNA (mRNA) for interleukin-2, 3, 4, and 5, granulocyte-macrophage colony-stimulating factor (GM-CSF), and interferon gamma by in situ hybridization with 32P-labeled complementary RNA. Localization of mRNA to BAL T cells was assessed by simultaneous in situ hybridization and immunofluorescence and by in situ hybridization after immunomagnetic enrichment or depletion of T cells. As compared with the control subjects, the subjects with asthma had more BAL cells per 1000 cell that were positive for mRNA for interleukin-2 (P less than 0.05), 3 (P less than 0.01), 4 (P less than 0.001), and 5 (P less than 0.001) and GM-CSF (P less than 0.001). There was no significant difference between the two groups in the number of cells expressing mRNA for interferon gamma. In the subjects with asthma, mRNA for interleukin-4 and 5 was expressed predominantly by T lymphocytes. Atopic asthma is associated with activation in the bronchi of the interleukin-3, 4, and 5 and GM-CSF gene cluster, a pattern compatible with predominant activation of the TH2-like T-cell population.

Although the prevalence of asthma and morbidity related to asthma are increasing, little is known about the natural history of lung function in adults with this disease. We used data from a longitudinal epidemiologic study of the general population in a Danish city, the Copenhagen City Heart Study, to analyze changes over time in the forced expiratory volume in one second (FEV1) in adults with self-reported asthma and adults without asthma. The study was conducted between 1976 and 1994; for each patient, three measurements of lung function were obtained over a 15-year period. The final data set consisted of measurements from 17,506 subjects (8136 men and 9370 women), of whom 1095 had asthma. Among subjects who participated in all three evaluations, the unadjusted decline in FEV1 among subjects with asthma was 38 ml per year, as compared with 22 ml per year in those without asthma. The decline in FEV1 normalized for height (FEV1 divided by the square of the height in meters) was greater among the subjects with asthma than among those without the disease (P<0.001). Among both men and women, and among both smokers and nonsmokers, subjects with asthma had greater declines in FEV1 over time than those without asthma (P<0.001). At the age of 60 years, a 175-cm-tall nonsmoking man without asthma had an average FEV1 of 3.05 liters, as compared with 1.99 liters for a man of similar age and height who smoked and had asthma. In a sample of the general population, people who identified themselves as having asthma had substantially greater declines in FEV1 over time than those who did not.