Role of suppressor cells in immunological maturation

Neonatal mice exhibit high suppressor cell activity that can be measured by the ability of their spleen cells to suppress the in vitro response of adult mouse spleen cells to alloantigens in mixed lymphocyte culture. In this paper we have compared the changes in splenic suppressor cell activity after birth with the changes in immunological maturity, the latter being measured by mixed lymphocyte reactivity of the neonatal spleen cells. The data indicate that there are significant strain differences in the postnatal changes of suppressor cell activity. The results further indicate that four of the five mouse strains tested (C57BL/6, B10.A(5R), B10.A, and DBA/2) demonstrate a good correlation between the decrease in suppressor cell activity and increase in mixed lymphocyte reactivity of mouse spleen cells after birth. In one strain (B10.A(3R)), however, the suppressor cell activity drops to adult levels before full mixed lymphocyte reactivity is achieved. The results suggest that, although suppressor cells may have a role in immunological maturation, other factors may contribute to the development of immunocompetence.