A group of renal pathologists, nephrologists, and transplant surgeons met in Banff, Canada on August 2-4, 1991 to develop a schema for international standardization of nomenclature and criteria for the histologic diagnosis of renal allograft rejection. Development continued after the meeting and the schema was validated by the circulation of sets of slides for scoring by participant pathologists. In this schema intimal arteritis and tubulitis are the principal lesions indicative of acute rejection. Glomerular, interstitial, tubular, and vascular lesions of acute rejection and "chronic rejection" are defined and scored 0 to 3+, to produce an acute and/or chronic numerical coding for each biopsy. Arteriolar hyalinosis (an indication of cyclosporine toxicity) is also scored. Principal diagnostic categories, which can be used with or without the quantitative coding, are: (1) normal, (2) hyperacute rejection, (3) borderline changes, (4) acute rejection (grade I to III), (5) chronic allograft nephropathy ("chronic rejection") (grade I to III), and (6) other. The goal is to devise a schema in which a given biopsy grading would imply a prognosis for a therapeutic response or long-term function. While the clinical implications must be proven through further studies, the development of a standardized schema is a critical first step. This standardized classification should promote international uniformity in reporting of renal allograft pathology, facilitate the performance of multicenter trials of new therapies in renal transplantation, and ultimately lead to improvement in the management and care of renal transplant recipients.

The pathological features of 20 cases dying in status asthmaticus have been studied. In gross sections the lungs showed no emphysema, but mucus plugs in the air passages and focal areas of collapse were outstanding features. Five cases showed cystic bronchiectasis which was of a similar distribution to the focal areas of collapse, occurring in the upper lobes as commonly as in the lower lobes.Histologically, shedding of the ciliated bronchial mucosal cells was prominent and this is attributed to a transudation of oedema fluid from the submucosa. Areas of regeneration of the mucosa, with the presence of simple stratified epithelium, were seen frequently. The loss of the ciliated respiratory epithelium and the transudation of oedema fluid into the bronchial lumen, with interference with the action of the remaining ciliated cells, are considered to be the essential factors in the failure of clearance of the bronchial secretions in asthma. It is postulated that bronchospasm plays little or no part in the shedding of the bronchial mucosa or in the pathogenesis of the asthmatic attack.

Clinico-pathological correlation has always been one of the main aims of the morbid anatomist. However, although clinical physiologists have for many years expressed their results in a quantitative form, pathologists have progressed mainly, though not entirely, along a descriptive path. Descriptive pathology has reached a high degree of refinement with the study of ultra-structure by the electron microscope and the probing of cellular chemistry by histochemical methods. Little interest has been shown in the field of quantitative morphology, although a quantitative study of gross and microscopic pathology, correlated with the findings of physiopathologists, might well yield much useful information. Thompson (1917) pointed out many applications of this approach to general biology, and recently Grant (1961) has drawn attention to the importance of this type of study in cardiac pathology and has referred to the work of Linzbach (1960). This paper is concerned with the methods of quantitation as applied to the lung, but the methods mentioned are capable of adaptation to almost any organ.

The proto-oncogene bcl-2 is abnormally expressed in some lung carcinomas, and its expression may have prognostic importance.

The quantitative anatomy of the bronchi has been studied in sudden deaths in normal subjects, in deaths from status asthmaticus and chronic bronchitis, and in patients with emphysema. In the normal bronchi the observed range of values for the percentage volume of mucous glands was between 7 6 and 16 7. In the status asthmaticus group the mucous gland volume was greatly increased and in no case was there an overlap with the normal subjects. In a previous paper (Dunnill, 1960) the pathological anatomy of the bronchi in asthma was described with special reference to the mucosal changes. The outstanding feature at necropsy was the presence of numerous plugs of mucus in the airways. Histologically, shedding of the ciliated bronchial mucosa cells was prominent, and this was attributed to a transudation of oedema fluid from the submucosa. The loss of the ciliated epithelium, together with interference with the action of the remaining ciliated cells by the oedema fluid, were considered to be the essential factors in the failure of clearance of the bronchial secretions in asthma. The finding of smooth muscle hypertrophy emphasized by Huber and Koessler (1922) was also noted. The present paper is concerned with the quantitative differences in the bronchial wall between normal subjects and those with status asthmaticus, chronic bronchitis, and emphysema. MATERIALS AND METHODSThe bronchi were divided into four groups, and were from (1) normal individuals who had died suddenly, usually a traumatic death, with no previous history of chronic bronchitis; (2) patients who had died in status asthmaticus; (3) patients who had died with a history of chronic airways obstruction with expectoration and who, on pathological examination of their inflated lungs, were found not to have any destructive emphysema-chronic bronchiti^s; (4) patients who had died with chronic airways obstruction and were found at necropsy to have one of the varieties of destructive emphysema.The majority of the lungs were fixed by the formalin steam method of Weibel and Vidone (0961). but in the status asthmaticus lungs, due to the dense bronchial exudate, this was often not possible. and the lungs were fixed by perfusion of the vessels wvith 10% formol saline.Transverse histological sections, 5/1 thick, were taken at three different levels from each bronchus selected (vide infra). Points of bifurcation were avoided. The sections were stained by the Masson trichrome and periodic acid Schiff tethniques, as well as by haematoxylin and eosin. Sections. viewed with a Leitz Ortholux microscope fitted with a x4 objective and a projection mirror, were projected on to a piece of Bristol board with a point-counting grid drawn on it, the points being placed at the angles of equilateral triangles of side 0-6 cm. The details and rationale of the point-counting procedure have been described in previous papers (Dunnill, 1962;Anderson and Dunnill, 1964). Points falling on the bronchial wall were allocated to cartilage, muscle, mucous gland or 'connective tissue'. The latte...