Mouse milk cells were stained with rhodamine or fluorescein isothiocyanate and fed to young suckling mice. By visual examination of serial sections and by flow cytofluorometry, we were able to demonstrate directly the presence of these cells in peripheral tissues. It was estimated that at least 0.1% of the fed cells might infiltrate the young mouse, which is initially immunologically defenseless. This is in accordance with evidence from many sources for activity of maternally-derived lymphoid cells in young rodents.

In BALB/c mice, antibodies to the alpha-(1-3) glucosidic linkage of some dextrans (Dex) carry the idiotype of the BALB/c myeloma protein J558. Both specific antibody and idiotype are inherited in a dominant fashion, linked to the immunoglobulin (Ig) (heavy chain) allotype Igla of BALB/c mice (Eur. J. Immunol. 1975. 5: 775). In F1 hybrid mice from the parent strains SJL and BALB/c, we were able to suppress the expression of anti-Dex antibodies by immunizing prospective SJL mothers to the J558 idiotype. The state of suppression in the progeny was ascertained by immunization with Dex, and tests for the following were carried out: (a) antibodies specific for Dex; (b) inhibition of such antibodies (if present) by antiidiotypic serum to protein J558; (c) presence of the J558 idiotype; and (d) concentration of lambda1 chains (which are associated with the 558 idiotype) in the serum. SJL mothers, once immunized, conferred suppression upon several successive litters, spanning a period of 4-5 months. Suppression in F1 progeny animals lasted for 16 weeks or more. Spleen cells from suppressed F1 mice which had neither been treated with Dex nor with J558 protein, were able to confer suppression to further F1 newborn mice.

No abstract

Antibodies t o the determinant oligo-D-alanine can be characterized by the speed of their association and dissociation with multivalent antigen. The antigen is present on the surface of sheep red blood cells (SRBC) as dense clusters, formed by poly-alanylated rabbit antibodies against SRBC. Anti-Dala IgG molecules attached to such "receptors" sensitize SRBC for subsequent lysis by complement, provided they are complexed with anti-allotype antibodies ("facilitation"). Kinetic curves for the association reaction (at 5 "C) or for the dissociation reaction (at 35 "C) indicate whether antibody populations are heterogenous or homogenous in their kinetic properties.Even when mice are of the same genetic constitution, antisera from individual mice may show up to 3O-fold differences in association velocities.The use of anti-allotype antibodies as facilitating reagents allows the separate kinetic analysis of allotypically defined antibody subpopulations within heterozygous animals. Such subpopulations were found to be distinct and independent with respect to association-dissociation characteristics.

Nude mice bearing allotype Ighb on a BALB/c genetic background (= CB nu/nu) are nonresponders to alpha (1----3)dextran (Dex), in contrast to BALB/c or BALB/c nu/nu. Although CB nu/nu mice accept transplants of congenic BALB/c, or BALB nu/nu lymphocytes, as shown by the expression of donor allotype Igha, they are not permissive for a primary anti-Dex response by the grafted cells. BALB/c or BALB nu/nu cells, however, give a strong anti-Dex response when grafted onto irradiated CB nu/nu or CB 23 (Ighb) euthymic mice. A thymus-independent, radiation-sensitive suppressor cell population is postulated, which specifically hinders the anti-Dex response, and which is exhibited by strains bearing that portion of chromosome 12 which codes for CH allotype Ighb, not containing the germ-line anti-Dex V/D genes. The suppressive action of Ighb lymphocytes could be demonstrated directly in staggered co-transfer experiments.