SUMMARY The incidence of reactive thrombocytosis in active pulmonary tuberculosis was studied in 122 patients. Thrombocytosis was common, platelet counts often exceeding I x 1012/1. A significant inverse correlation was noted between the mean platelet volume and the platelet count (r = -0 54, p < 0 0001). Interval estimation suggested that this relation was non-linear. Further studies were done in a small group of six patients. Platelet survival was considerably shortened, the platelets aggregated excessively in vitro, serum concentrations of thrombopoiesis stimulating activity were raised, and serotonin uptake and release were within normal limits. The degree of thrombocytosis correlated significantly with the degree of inflammation measured by the erythrocyte sedimentation rate (r = 0 40, p < 0 003) and serum C-reactive protein concentration (r = 0 35, p <0-008).Thrombocytosis occurs in many chronic inflammatory diseases, including tuberculosis.' 4 The precise stimulus for increased platelet production in reactive thrombocytosis is not clear, but it is associated with increased numbers of small megakaryocytes in the marrow,4 6 which show reduced nuclear ploidy.5 The platelets are also small,7-9 but it has recently been suggested, that this may simply reflect the thrombocytosis, as there is normally an inverse correlation between the number and volume of platelets. "' The present study was done to define reactive thrombocytosis in acute tuberculosis with particular reference to the association between the volume and number of platelets, their survival, and certain aspects of their function. Patients and methodsOne hundred and twenty two patients with pulmonary tuberculosis were studied; most were of black or mixed racial origin. Twenty were newly diagnosed and about to begin antituberculous treatment, 82 had been diagnosed recently and were already being treated, and 20 were nearing the end of a six month course of treatmeilt. A full blood count was done-in

old were inoculated with the Jensen sarcoma and the phagocytic index of the reticuloendothelial system was measured a t various stages of tumor growth. The older animals bearing the Jensen tumor produced more and an earlier stimulation in the rate of carbon clearance than the younger tumor-bearing animals.In a study of the in vivo aging of rat blood platelets, the relative sizes of platelets tional Refrigerated Centrifuge: model PR-2) for 40 minutes, the platelet-rich plasma-saof young, old, and normal populations were compared by measuring with a cathetometer the volumes of packed platelets in microhematocrit tubes; it was found that platelet size decreases with age( 1). The purpose of this study was to investigate the frequency distributions of platelet sizes in populations of varying age using a Coulter Electronic Particle Counter with a particle size distribution plotter attached( 2,3).Methods. Blood was drawn from the abdominal aorta of anesthetized male Sprague-Dawley rats into cold, siliconed 20-ml syringes containing 1 ml of a 1% solution of filtered ethylenediaminetetraacetic acid (EDTA) in 0.7% saline. All diluents used were filtered through a filter having 0.45 p pore size. A standard volume of 10 ml of blood was collected from each rat and was diluted with 6.25 ml of filtered saline to obtain a better yield of platelets. The bloodsaline mixture of each rat was equally divided into two 15-ml conical centrifuge tubes, and the platelets were separated by differential centrifugation in a refrigerated centrifuge (5°C). After a slow centrifugation of the blood a t 107 X g (750 rpm in an Interna-~ *Operated by Union Carbide Corp. for U. S. Atomic Energy Commission. line was removed and spun more rapidly a t 760 X g (2,000 rpm) for 30 minutes to obtain a platelet button. The platelets were then resuspended in 0.9% saline to give concentrations of 9,747 to 37,030 platelets/50 p1. (The standard volume of suspension pulled through the counting aperture was 50 pl when making numerical counts.) Platelets that had been separated from blood and resuspended in saline were used in these experiments rather than diluted platelet-rich plasma because our own work and that of others(4) has indicated that, in addition to platelets, the latter may contain unidentified small particles that affect platelet counts and possibly size distribution curves.Populations of young platelets were obtained from rats that were recovering from thrombocytopenia induced with antiplatelet serum( 1 ) . Four hours after injection of the antiplatelet serum there were no circulating platelets. At 24 hours the platelet count was approximately 4,000/mm3, which was too few for satisfactory collection. Platelets were collected and sized 2, 3, 4, 5 , 6, and 7 days after antiserum injections. Platelets collected 2 days after antiserum injection, therefore, had an age range of 0-2 days.Populations of old platelets were prepared at GEORGETOWN UNIV MED CTR on July 22, 2015 ebm.sagepub.com Downloaded from

No abstract

An assay describing conditions for the maturation of single immature megakaryocytes in vitro is reported. Enriched populations of small, relatively immature megakaryocytes have been found to develop into single, mature megakaryocytes by 60 hours in semisolid agar cultures. Continued incubation of these cells did not lead to the formation of colonies within 5-7 days. Maturation was indicated by increasing cell size and cytoplasmic and acetylcholinesterase content. Factors stimulating the development of immature megakaryocytes were found in preparations of human embryonic kidney cell-conditioned media (a source of in vivo Thrombopoietic Stimulatory Factor), peritoneal exudate cell-conditioned medium, lung-conditioned medium, or bone marrow cellular sources of activity (adherent cells or cells that sediment at 5-6 mm hr-1). Immature megakaryocytes cultured serum free responded to sources of an auxiliary megakaryocyte potentiating activity by developing into single, large megakaryocytes but did not respond to a megakaryocyte colony-stimulating factor devoid of detectable potentiator activity present in WEH1-3-conditioned medium. In contrast, serum-free proliferation of the megakaryocyte progenitor cell required both megakaryocyte colony-stimulating factor and the auxiliary potentiator activity. In the presence of megakaryocyte colony-stimulating factor alone, progenitor cells did not form colonies of easily detectable megakaryocytes. However, groups of cells comprised entirely of small acetylcholinesterase containing immature megakaryocytes were observed, thus establishing that megakaryocyte colony development passes through a stage of immature cells prior to detectable megakaryocyte development and that some acetylcholinesterase-containing cells can undergo cellular division.