Cross-reactivity patterns of IgM and IgG anti-lipopolysaccharide antibodies in individual mice

Unidirectional IgG allotype- and isotype-specific suppressor cells in congeneic mice

By the use of allotypic markers on immunoglobulin molecules of isotypes IgG1 and IgG2a, in transfers of spleen cells between Igh haplotype congeneic partner strains BALB/c (Igha) and CB20 (=BALB/c-Ighb), the expression of donor and recipient lymphocytes could be followed differentially. BALB/c donor's allotype a was produced in nonirradiated CB20 recipients for months. By contrast, CB20 donor's allotype b disappeared in nonirradiated BALB/c recipients shortly after transfer. These BALB/c recipients of CB20 spleen cells ("CB20-primed") developed lymphocytes which were able to suppress the autochthoneous allotype b production of CB20 irradiated or CB20 nu/nu or neonatal F1 (BALB/c female X CB20 male) recipients immediately after transfer. Titers decreased with a half life of about 4 days, resembling that of immunoglobulin molecules. The suppression was restricted to the IgG2a isotype of allotype b. Neither the other isotype IgG1 of allotype b, nor, in the reciprocal transfer experiment, IgG1 or IgG2a of allotype a was affected. Analogous transfers between Igh congeneic partners on a C57B1/6 genomic background revealed the same susceptibility of allotype b-producing cells from C57B1/6 donors toward suppression by C57B1/6-Igha mice as recipients. Allotype suppression, induced by cell transfer, is thus unidirectional in that Igha haplotype mice react against allotype b but not vice versa, and it is isotype-specific, only directed against IgG2a, and not IgG1.

Inheritance of antibody specificity: the IgM anti-lipopolysaccharide response in mice

Mice of different genotypes were immunized with Salmonella anatum. The cross-reactivity patterns of their IgM anti-S. anatum lipopolysaccharide (LPSAN) antibodies were characterized by their relative avidity toward heterologous LPS. When the LPS from S.cholera suis (LPSCHS) was used as the heterologous LPS, clear differences between mouse strains were found. DBA/2 and DBA/1 showed cross-reacting IgM, whereas C57BL/10, C57BL/6 BABL/c-Igb and B10. D2 had mainly noncross-reacting IgM. In C3H and C57BL/6-Iga, individual mice express either the cross-reacting or the noncross-reacting antibodies. The IgM antibodies from individual mice were further characterized for their cross-reactivity toward the LPS from S. strasbourg (LPSSTR) and S illinois (LPSILL). Only individual patterns with no correlation to the cross-reactivity pattern with LPSCHS were found.This shows that more than one antibody type is characterized by cross-reactivity.(B10.D2 X DBA/1)F1 mice showed a biphasic distribution of cross-reactivity. Of the F1 X DBA backcross mice 21% had IgM antibodies which showed no cross-reaction with LPSCHS. This still is in agreement with one locus controlling this phenotype. This locus segregates independently from Ig allotype since no correlation was found between allotype and cross-reactivity pattern in F1 X DBA backcross mice.