Regulation of B-cell expression as revealed in the congenic barrier: exerted by B cells, augmented by T cells, and directed toward memory as well as naive donor B lymphocytes.

Donor's memory cell expression is reduced in nonirradiated recipients as compared to irradiated ones. This "barrier" was studied in Igh-congenic BALB/c mice as transfer partners, making use of their allotypic markers, under two aspects: (I) Does the barrier apply to naive B-cells also, not only to memory cells? (II) Does a barrier exist in nude recipient mice also? (I) Naive donor B cells were subject to a barrier in nonirradiated recipients as well as memory cells. (II) Nude recipients showed a barrier toward naive donor cells like euthymic hosts, but toward memory cells this was less stringent. The allotypically marked donor B cells survived and were active in the nonirradiated host. In some situations they even dominated the host's response. The results favor a concept of the barrier as an "intrinsic" interlymphocytic control, exerted by B cells, augmented by T cells, best explained by Jerne's theory of idiotypic interactions.