Is the primary complement lesion insufficient for lysis? Failure of cells damaged under osmotic protection to lyse in EDTA or at low temperature after removal of osmotic protection

The extent of damage to cell membranes induced by specific antibody and complement under various conditions was monitored by leakage from the cells of isotopically labeled molecules of three sizes. The results have revealed that cells which have sustained complement-mediated membrane damage (indicated by loss of electrolytes) do not, in the absence of osmotic protection, proceed to undergo rapid colloid osmotic lysis, provided that (1) the primary complement-mediated damage was sustained in osmotically protective medium, (2) the damage was of limited extent, and (3) complement activity is stopped (by EDTA or low temperature) prior to removal of osmotic protection so that additional new damage is not done after the removal of osmotic protection. This was found both for mouse ascites tumor cells and erythrocytes. Moreover, the results suggest striking differences in the effect of low temperature on the lytic process in nucleated cells as compared with erythrocytes. In addition to the above-mentioned effects, low temperature can apparently prevent leakage of molecules as small as amino acids from damaged nucleated cells (but not from erythrocytes) in the absence of ostomic protection, no matter how extensive the previous (prelytic) complement-mediated damage, and irrespective of whether the cells were osmotically protected while the damage was administered. These findings have two, perhaps unrelated implications. First, low temperature has a striking ability to restrict further loss of intracellular constituents from damaged nucleated cells (but not from erythrocytes). Second, the results with nucleated cells and erythrocytes raise the possibility that the primary complement-induced lytic lesion either reseals spontaneously or is capable of being repaired.