Effect of the cationic environment on immune haemolysis of high potassium and low potassium sheep erythrocytes.

Immune haemolysis was studied with the two types of genetically controlled sheep erythrocytes (E) which contain either high potassium (K) and low sodium (Na) (HK E) or low K and high Na (LK E). It was found that the susceptibility of HK and LK E to lysis by guinea-pig and human complement is influenced by the cationic environment. In veronal buffer containing 0.140 M sodium, caesium, choline or Tris, HK E were less susceptible to immune lysis than LK E. No difference was observed in potassium and in lithium(Li). Immune lysis of HK E was stimulated by the cationic series: K>Li>Rb>Cs>Na. Immune lysis of LK E was less dependent on the cationic environment, but K had a slight stimulatory effect. HK and LK E had similar reactivity with haemolytic antibody and in immune adherence. The enhancing effect of potassium was demonstrable upon E (an erythrocyte which has been damaged by complement but has not yet undergone lysis), suggesting that the cationic effect is produced in the final steps of immune lysis. The data suggest that the different reactivity of HK and LK E with complement in a sodium medium might be independent of the cationic permeability properties of the membrane. Inhibition of active transport by ouabain did not modify the reactivity of HK and LK E with complement in a sodium medium.