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Measurements of integrated optical density and projected area of red cells have been made on Romanowsky-stained blood films from 25 subjects using an image analysing computer. Close correlation was observed between mean cell projected area and MCV and between mean cell integrated optical density and MCH. Mean values for the quotient of cell integrated density/cell projected area (mean cell colour density) correlated with MCHC. Varieties of cell area and colour density correlated subjectively with anisocytosis and anisochromasia, and histograms of these parameters demonstrated dual populations. The clinical application of these findings is discussed.

During sterile incubation of normal human erythrocytes at 37 degrees C., intracellular nonhemoglobin protein is bound to the membrane prior to hemolysis. These studies have characterized this phenomenon further. Protein binding to the membrane began after 12 hours incubation when cellular ATP was depleted and increased to 36 hours incubation. The binding was prevented by adding adenosine or glucose at the start of incubation and was arrested by adding adenosine to regenerate ATP during the course of incubation. However, protein, once bound, was not released by regeneration of ATP. The amount of protein bound was not altered by: (1) addition of Ca++ or EDTA to the medium, (2) blockade of sulfhydryl groups with N-ethylmaleimide, or (3) stabilization of heme-globin bonds by conversion of hemoglobin to cyanmethemoglobin. Conversion of hemoglobin to carboxyhemoglobin by incubations under carbon monoxide inhibited protein binding, but this appeared to be an effect of exclusion of oxygen rather than stabilization of heme-globin bonds since incubation under nitrogen had a similar effect. The morphological counterpart of this chemically-measured membrane-bound protein was visible in red cell ghosts stained with crystal violet as small membrane-associated particles resembling Heinz bodies. Sodium dodecyl sulfate acrylamide gel electrophoresis of membranes of incubated cells revealed a new protein band that was identical to globin monomers. This membrane binding of globin during incubation provides a model for the study of Heinz body formation in clinical disorders.

The cortex of the thymus glands of embryos, chicks, juveniles, fledglings and adults from several colonies of Quelea quelea were studied using an image analyser (Quantimet 720) to determine cell populations and nuclear sizes. Just prior to hatching the lobes showed a high level of mitosis and consisted of predominantly small lymphocytes. The larger glands of chicks and juveniles had higher cell populations; pyknotic cells and erythrocytes occurred free in the cortex. The lobes of adults were more variable but in general mitosis occurred in enlarging glands of adults from colonies with eggs; most lobes contained pyknotic cells but not in such high numbers as in lobes from chicks and fledglings. Erythrocytes were common, occurring in large numbers in the cortex in some birds. The factors affecting the interpretation of these data are discussed in detail.

The effects of the hallucinogen, harmaline (HME), and its congeners on human red blood cell (RBC) transport were studied. HME reduced sodium efflux by 70% at maximum inhibitory concentrations (6-8 mM). It acted upon the ouabain-sensitive component of sodium efflux since it exerted no inhibitory actions in the presence of ouabain. Several lines of evidence suggested that HME exerted its inhibitory effect at intracellular sodium-sensitive sites. The percent inhibition of Na efflux by 0.1 mM HME was unaffected by increasing extracellular potassium from 10 to 100 mM. When HME was incorporated into RBC ghosts by reversible hemolysis, the degree of inhibition of sodium efflux was comparable to that found with ouabain outside the red cells and was always greater than the inhibition produced with HME outside cells. HME increased membrane permeability to sodium, as shown by enhanced sodium influx into RBC and at concentrations of 10 mM caused rapid increments of intracellular sodium and decrements of intracellular potassium. We conclude that the harmala alkaloids inhibit the active Na-K transport system in human RBCs through their effects on sodium-sensitive transport sites on the interior membrane surface.

Differentiation of red blood cells occurs in organ cultures of both livers and kidney tissue from tadpoles of the bullfrog Rana catesbeiana. Our evidence indicates that different red blood cell lines are produced by the two tissues and that these different cell lines contain different tadpole hemoglobins.