Effect of Anti-Allotype Sera on Hemolytic Plaque Formation by Single Rabbit Spleen Cells

Summary Examination of the effects of anti-allotype sera on hemolytic plaque formation by rabbit spleen cells has revealed the following effects: 1.Plaque formation is usually inhibited by the anti-allotype sera if the cells are obtained from rabbits undergoing the initial response to sheep red blood cells. 2.Plaque formation is usually enhanced by the anti-allotype sera if the cells are obtained from rabbits undergoing the secondary response to sheep red blood cells. 3.A single anti-allotype serum directed against an allotypic specificity present on either the H-chain or the L-chain may give either inhibition or enhancement depending upon the source of the PFC as given in 1 and 2 above. 4.Both the inhibition and the enhancement appear to be mediated through the action of the anti-allotype sera on the hemolysin produced rather than directly on the cells producing it.