EFFECTS OF MONOCLONAL-ANTIBODIES ON ALPHA-STAPHYLOTOXIN ACTION AGAINST ERYTHROCYTES AND MODEL PHOSPHOLIPID-MEMBRANES

It was found that one of twenty tested monoclonal antibodies (MABs) ex isted which drastically enhanced ability of Staphylococcus aureus alph a-toxin (ST) to both lysis of human erythrocytes and increase of plana r phospholipid bilayer conductance more than 10 and 1000 times respect ively. Other 19 MABs possessed only neutralized effect. The activation could only be observed if the activating MAB (AMAB) interacted with S T in solution but not in membrane. The one molecule of AMAB was able t o activate approximately 2-4 molecules of ST. It was assumed that this activation was a result of the AMAB-induced transition of ST from a h ydrophilic to an amphiphilic form. The activation could not be observe d when the activity of AMAB/ST mixtures was tested on highly sensitive rabbit erythrocytes. All the tested MABs (including AMAB) were able t o inhibit the ST-induced lysis of rabbit erythrocytes. The activating effects of AMAB on ST action in BLM and in human erythrocytes as well as their inhibiting influence on the ability of toxin to cause a lysis of rabbit erythrocytes indicate the presence of an ST-specific recept or on the membrane of rabbit erythrocytes.