Interaction of maternal and neonatal cells in mixed-lymphocyte cultures.

One-way and two-way mixed-lymphocyte cultures of cells from male newborn infants and their parents were studied. The tests between the lymphocytes of the parental pairs in the one-way system, in which one population stimulates and the other responds, indicated that maternal lymphocytic response was not generally depressed. However, there was some evidence that the response of the maternal cells was depressed when the cells of the newborn infant were stimulatory. When both maternal and neonatal lymphocytes were viable and the origin of the dividing cells was monitored by using sex chromosomes as markers, it was clearly shown that the division of maternal cells was inhibited, most of the metaphases being XY. The mechanism of this inhibition may depend on contact between viable cells or on the liberation of inhibitory factors by the neonatal cells.