Impaired capacity of the macrophages of newborn mice for T-lymphocyte activation by phytohemagglutinin.

The level of collaboration in phytohemagglutinin (PHA) induced lymphoblastic response by the macrophage of neonatal mice was studied. The results show a diminished response to the mitogen (PHA) when lymphocytes from the spleen of syngeneic adult mice were incubated in the presence of macrophages from neonatal mice as compared to those obtained from cultures performed in the presence of macrophages from adult mice. In both cases the highest response corresponded to the lowest dose of PHA and the lowest amount of macrophages used.