Maternal influence on the immune response: SMLC reactions between identical and reciprocal F1 hybrids and the role of lactation.

Identical and reciprocal adult F1 mice from different strain combinations, either nursed on their own mothers or foster-nursed on mothers from the paternal strain, were used to carry out SMLC assays. The results obtained showed that: (1) in vitro proliferation of F1 T cells was significantly different when splenocytes from identical versus reciprocal hybrids were used as the stimulatory population, splenocytes from one of the members of the reciprocal pair being able to induce higher proliferative responses of T cells from both identical and reciprocal F1 hybrids; (2) foster-nursing of F1 hybrids on mothers from the paternal strain was able to induce permanent alterations in the ability of their splenocytes to stimulate the proliferation of responder F1 T cells. The stimulatory ability of splenocytes from foster-nursed hybrids was indistinguishable from that observed in the reciprocal F1 combination nursed by its own mother. The existence of a maternal effect acting through milk on the outcome of self recognition in the litter is discussed.