The Immune Response in NZB and NZB × C3H F1-Hybrid Mice as Measured by the Haemolysin Plaque Technique

Abstract

In unstimulated mice the average background count of sheep red cell reactive plaque forming cells is higher in young Coombs negative NZB-mice than in C3H-mice of similar age. NZB-mice of positive Coombs reactivity are not significantly different in their background of plaque forming cells from C3H-mice and from older but still Coombs negative NZB-mice. The kinetics of response to a single injection of 4 x 108 sheep red cells in different mouse populations show the following features. In C3H, (C3H x NZB) F1 and Coombs negative NZB-mice, the peak of plaque forming cells is at 4 to 5 days. In NBZ-mice of Coombs positive reactivity the mean peak of plaque forming cells is about 11 fold lower and is reached only at 7 days. The delay is mainly in the time taken for the plaque forming counts in the NAB-mice to emerge from the background level. When the estimation of plaque forming cells at day 4 is taken as a criterion, the yield in NZB-mice falls sharply with the correlated changes of Coombs conversion and splenic enlargement with age. The fall is more intense in relation to the splenomegaly in these mice, than the fall with age seen in (C3H x NZB) Fl hybrids, where neither splenic enlargement nor Coombs conversion has occurred.