The discocyte-stomatocyte equilibrium of normal and pathologic red cells.

By R. I. Weed and M. Bessis T HE DISCOCYTE-ECHINOCYTE transformation has become well known through the studies of Jolly,’ Ponder,2 Teitel-Bernard,3 Furchgott and Ponder,4 and, more recently, by Weed et al.5 and Bessis and Lessin.68 This subject has been recently reviewed in this journal by Brecher and Bessis.9 Certam characteristics of this transformation have been established. Intrinsic factors (i.e., depletion of ATP5”#{176}” or extrinsic agents (e.g., lysolecithin, anionic detergent-like compounds,’2 uranyl salts,’3 sodium oleate, or elevated pH2’9’4 can induce normal discoid erythrocytes to undergo the echinocyte transformation. This transformation also appears to be dependent on intramembrane calcium and its turnover.’4 Exaggeration of the predisposing conditions, such as by employing increased concentrations of extrinsic agents, will lead to the formation of spheroechinocytes and prelytic spheres that are not reversible. Pathologic erythrocytes, no matter what their shape, (e.g., poikilocytes, acanthocytes, or sickle cells) can, like normal red cells, respond to these same agents and develop echinocytic forms.7’8 The underlying pathologic shape persists, and secondary (new) spicules may be superimposed on primary spicules so as to give rise to echinopoikilocytes (e.g., echino-sickle cells, echinoacanthocytes, etc.). In spite of the number of studies dealing with the distinctions between echinocytes, on one hand, and various other types of crenated or spiculated cells (such as acanthocytes, spur cells, burr cells, keratocytes, etc.) on the other, it is apparent that confusion persists in the literature in regard to these forms. Even less well known and appreciated than the discocyte-echinocyte equilibrium is another type of shape change. This is the discocyte-stomatocyte transformation, which, in a sense, is the converse of the echinocytic transformation. The limited number of investigators who have studied the stomatocytic change have described this transformation as occurring with decreased pH,”5”6 as well as with certain chemical agents, particularly cationic detergent-like compounds and nonpenetrating anions.12 Low concen-