Trapped plasma in the microhematocrit.

The amount of trapped plasma in the microhematocrit red blood cell column of samples from 25 normal individuals and 102 patients was investigated. The mean value for the normal individuals was 1.53%, and the mean values for the samples from the patient groups ranged from 1.41% to 1.82%. These groups included patients with sickle cell disease, iron deficiency, and hereditary spherocytosis. There was an inverse correlation between trapped plasma and the MCH in the samples from patients with iron-deficiency (MCH less than or equal to 25.0 pg). These findings have relevance to the determination of the PCV and derived red blood cell indices.

The interpretation of measured red cell mass and plasma volume in patients with elevated PCV values.

Various formulae using both height and weight have been proposed to interpret measured red cell mass (RCM) and plasma volume (PV). This paper compares four different methods for evaluating these measurements in 50 males with PCV values above 0.51 and three different methods for evaluating results in 50 females with PCV values above 0.49. Overall there was close agreement in the RCM result expressions by all methods for both males and females except at extremes of height and/or weight. The incidence of absolute polycythaemia in both sexes was influenced by the width of the normal range. When this was taken into account overall the incidence of polycythaemia was similar, but in a small number of individuals there were discrepancies of interpretation. These individual patient differences establish that decisions regarding further investigations of a patient must not rest on a strict interpretation of a measured RCM. The various methods of measured PV interpretation gave dissimilar results--in particular by one of the male PV interpretation methods. The differences in the methods almost certainly reflect methodological discrepancies in the original techniques used to establish the normal values. The differences in result expression for PV would however lead to a different incidence of relative, low plasma volume, polycythaemia by the various techniques.

PCV measurement in the management of polycythaemic patients.

The PCV of samples from normal individuals and polycythaemic patients being treated by venesection were measured using the microhaematocrit corrected for trapped plasma, radio-isotope dilution, the Coulter 'S' and Coulter 'S Plus'. There was no significant difference between the two manual methods for either the normal individuals or the polycythaemic patients. The Coulter S and S Plus gave lower values for PCV compared with the corrected microhaematocrit, particularly for the polycythaemic patients. The underestimation of the PCV by the Coulter instruments for the polycythaemic group was significantly related to the MCH and MCV. The under-estimation was approximately 6.4% and 7.4% at an MCH of 20 pg by the Coulter S and S Plus respectively. These findings have relevance to the management of polycythaemia by venesection if the effectiveness of treatment is monitored by measuring the PCV by a Coulter instrument.

Diabetes mellitus in the rat: diminution in the number of cells in the thymus and of lymphocytes in the blood.

In diabetic rats there is a rapid fall in the weight of the thymus with a great loss in the numbers of thymocytes. In this paper we show that there is also a marked diminution in the number of lymphocytes in the peripheral blood, although the numbers of neutrophils and monocytes are not affected. Since the thymus is thought to be the site in which T-lymphocytes develop, it is suggested that the paucity of lymphocytes in the peripheral circulation reflects the loss of cells from the thymus. The diminution in the number of circulating lymphocytes in diabetes may account for the liability of diabetics to suffer severely from infections.

The Ultra-Flo 100 platelet counter: a new approach to platelet counting.

The Clay Adams Ultra-Flo 100 whole blood platelet counter is a semiautomated instrument. The count is made on dilute whole blood by the detection of comparatively small current changes induced by the cells suspended in a conducting diluent as they flow thrugh an orifice. Alarm systems are incorporated in the instrument to detect sample irregularities due to microcytosis, and large and small platelets. The results of this evaluation are given, and confirm that the results using the Ultra-Flo 100 compare very favourably with those obtained using phase contrast microscopy.

Whole blood viscosity in polycythaemia: the effect of iron deficiency at a range of haemoglobin and packed cell volumes.

The effect of iron deficient red cells changes (MCH range 20.0-32.6 pg) on whole blood viscosity (WBV) at high and low shear rates (94.5 and 0.51 s-1), has been assessed at a wide range of standardized PCV (0.30-0.65) and standardized Hb values (10.0-22.0 g/dl). Particular attention was given to the precision of PCV measurement. At all PCV values there was no correlation between MCH and WBV, whereas at all Hb values there was a significant negative correlation between MCH and WBV. If the treatment of polycythaemia is by venesection, iron deficient red cell changes occur frequently. These changes are unimportant if control of the WBV is the objective of treatment, as long as the PCV is accurately measured. Alternatively, in the secondary polycythaemias, where oxygen saturation is reduced, the induction of iron deficient red cell changes could be regarded as disadvantageous since at a standard PCV of 0.50 the Hb and hence oxygen carrying capacity is reduced by approximately 11% between MCH values of 30 and 20 pg.

Electrophoretic analysis of red blood cells in polycythaemia.

In contrast with previously published observations, this study has found no increase in the net negative surface charge of the red blood cells (RBC) from patients with various forms of polycythaemia when compared with normal subjects. Two sub-populations of RBCs with different electrophoretic mobilities (EPM), termed fast and slow, were present in samples from both patients and normal individuals. Frequently, the slow cell population in RBCs from patients with polycythaemia, particularly the apparent polycythaemia sub-group, was of a lower EPM and contained more cells than the corresponding population in normal subjects. The membrane-bound sialic acid content of RBCs from patients with primary proliferative polycythaemia, associated with iron deficient RBC changes, was increased if the results were expressed per unit volume of RBCs and decreased if the sialic acid concentration was presented per number of RBCs. These results imply that differences in surface charge of RBCs are of no value in discriminating between primary and secondary polycythaemia.

Screening tests for Sezary cells in cutaneous T-cell lymphomas.

Blood samples from normal individuals (n = 7), from patients with cutaneous T-cell lymphomas (Sezary syndrome = 7; mycosis fungoides = 18) and from patients with chronic benign skin disease (n = 8) were examined for the presence of Sezary cells. The samples were analysed using a Coulter model S Plus IV with a three Cell Population upgrade, and a Becton Dickinson FACS analyser; and the results were compared with those obtained from morphological examination of peripheral blood films. Using the FACS analyser a population of aneuploid cells was only identified in two out of eight patients with confirmed circulating Sezary cells. This was in contrast to the results from the Coulter S Plus IV which detected an abnormality in six out of the eight samples with confirmed circulating Sezary cells. These results indicate that leukocyte volume analysis is a useful, additional screening tool for the identification of Sezary cells.

Interpretation of measured red cell mass and plasma volume in adults: Expert Panel on Radionuclides of the International Council for Standardization in Haematology.

Four European centres provided height and weight data on 202 males and 204 females undergoing red cell mass (RCM) and plasma volume (PV) measurements. For these populations, the RCM and PV predictions by the various published methods were compared. It was shown clearly that predictions based solely on body weight were inappropriate, particularly because approximately half of the male and female populations could be regarded as overweight or obese. Although there was reasonable agreement in the prediction values given by the formulae based on both height and weight, it was not possible to establish which formulae could be recommended. For that reason, the published literature containing normal RCM and PV measurements were re-examined. RCM data for 283 males and 171 females and PV data for 100 males and 67 females were included. Measurements were standardized for variables such as trapped plasma in the PCV, exclusion of buffy coat in the PCV and calculation of PV at zero time. As a result of this analysis, prediction formulae based on surface area for RCM and PV with 98/99% reference ranges have been established.

Platelet size: no correlation with migraine or monoamine oxidase activity.

A Coulter Model "S Plus" counter has been used to study platelets from 39 migrainous patients between attacks, six during attacks, eight with active cluster headache and 26 controls. None of the patient groups showed any abnormality in platelet size profile. There was no correlation between platelet monoamine oxidase activity and mean platelet volume in any of the groups.