The effects of idiotype on the ability of IgG1 anti-phosphorylcholine antibodies to protect mice from fatal infection with Streptococcus pneumoniae.

Anti-phosphorylcholine (PC) antibodies of the mouse are found in three different idiotype families: T15, M603 and M511. These subgroups exhibit different specificities for PC analogs and utilize light chains of different VL subgroups. In this study we have found that IgG1 antibodies of the T15 idiotype are much more protective against pneumococcal infection than IgG1 antibodies of the M511 or M603 idiotypes. This finding provides additional evidence that the T15 VH and VL genes may have evolved to protect mice from infection with PC-bearing pathogens.