In vitro studies on allotype suppression. IV. Abrogation of waning suppression by normal immunoglobulin of the suppressed allotype.

The mechanism of allotype suppression in rabbits has been investigated by studying the in vitro immune responses of spleen cells from rabbits in advanced stages of spontaneous recovery from suppression. Whereas the spleen cells from highly suppressed rabbits can be released from their suppressed state only if treated with a combination of antibodies against the non-suppressed type and immunoglobulin (Ig) of the suppressed type, treatment with either of these two components alone suffices to overcome suppression when cells of more poorly suppressed spleen donors are used. The demonstration that suppression can be abrogated by normal Ig of the suppressed type alone, when cells are obtained from rabbits in the final phases of suppression, lends further support to the previously suggested concept that the probable role of this normal Ig in the release phenomenon may be that of neutralizing an effector of allotype-specific repression, possibly involving suppressor cells.