There are few reports of reference ranges for haematological values in school age children and most studies extend over a small age range or have excluded a considerable proportion of the study population in an effort to omit those with haemoglobinopathies or anaemia. Blood samples from 2135 children aged 4-19 years, from randomly selected schools, were analysed by automated counter. Reference ranges for red cell, white cell and platelet indices are provided from the results. Median haemoglobin and red blood cell count values for girls and boys rose together with increasing age, up to 12 years, but then diverged. Girls had a higher platelet count than boys. Mean platelet volume rose with age and was inversely related to the platelet count. Plateletcrit fell with age but in girls there was a peri-pubertal peak. Total leucocyte count fell with age. The upper limits for total leucocyte count in this study are approximately 2 x 10(9) lower than those quoted in modern haematology textbooks. Lymphocyte, eosinophil and basophil counts fell with age with little difference between the sexes. Neutrophil and monocyte counts were similar for younger girls and boys but diverged in the older children with the older girls having higher values than boys.

Bronchial hyperresponsiveness can be produced experimentally after inhalation of numerous nonimmunospecific stimuli; our objective was to determine whether acrolein, a component of cigarette smoke, could increase bronchial reactivity to intravenously administered acetylcholine in guinea pigs. Bronchial responsiveness was assessed twice before and 1, 2, 6, and 24 h after exposures to less than or equal to 0.01 (sham), 0.31, 0.67, 0.94, or 1.26 parts per million for 2 h (5-7 guinea pigs/group). To examine the possible relationships of responsiveness to inflammatory mediator release and cellular infiltration, bronchoalveolar lavage was performed in another 30 guinea pigs before (control) and 0, 1, 2, 6, or 24 h after exposures. Pulmonary resistance was increased immediately after exposure (5 min) and returned to control values within 30-60 min. Increased bronchial responsiveness was evident within 1 h and became maximal 2-4 h after exposure. The acetylcholine dose necessary to double resistance decreased from 104.2 +/- 7.3 to 79.6 +/- 15.9 at 1 h and was 32.5 +/- 7.9 at 2 h and 32.8 +/- 7.6 micrograms.kg-1 at 6 h. Increases in two eicosanoids, thromboxane B2 (from 167 +/- 21 to 314 +/- 77 pg/ml) and prostaglandin F2 alpha (from 98 +/- 20 to 285 +/- 62 pg/ml) occurred immediately after exposure, whereas an influx of neutrophils occurred 24 h later (from 2.2 +/- 1.2 to 11.3 +/- 3.6%). These temporal relationships suggest that neutrophil infiltration may be a sufficient but not a necessary condition for the onset of bronchial hyperresponsiveness and that injury to cells normally present in the lung are responsible for the mediators thought to influence bronchial responsiveness.

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