Suppression of developed spleen haemolytic plaque formation by neonatal antigen stimulus in mice.

Non-specific antigen stimulus on the first day of life in mice led to profound depression (up to 10-fold) of splenic developed (IgG) haemolytic plaque forming cells (P.F.C.) in response to subsequent administration of another antigen (S.R.C.): a similar effect on direct (IgM) P.F.C. was significantly less. This immunoglobulin class-specific, but not antigen-specific, depression of immunity response by antigen occurred only in young mice and was transient. It is perhaps comparable to the IgG deficiency observed in infants with congenital rubella.