Influence of the nude and X‐Iinked immune deficiency genes on expression of × and λ light chains

Publisher Website
Google Scholar
Abstract
The relative amounts of Igx and Igλ1 anti‐2,4‐dinitrophenyl antibodies were measured at various times after immunizing mice with prototype thymus‐dependent (TD), thymus‐independent type 1 (TI‐1) and thymus‐independent type 2 (TI‐2) antigens. Similar amounts of Igλ1 were produced after TD and TI‐2 immunization and somewhat less was produced after a TI‐1 stimulus. In contrast, Igx levels were much greater after TD than after TI‐1 or TI‐2 antigen. The amount of light chain isotype produced appeared to depend on the molecular form in which the hapten was presented, although possible adjuvant effects were not ruled out. Levels of Igx and Igλ present in nonimmune sera were measured in normal, xid and nude mice. The x/λ, ratio was higher in xid than in normal mice and the difference was demonstrated by F1 analysis to be due to an X‐linked gene. Conversely, the x/λ ratio was lower in nude than in normal mice. This was true for the CBA/Tufts (Ighj), CBA. Ighb and C57BL/10 strains. However, there were no detectable differences in the relative frequencies of surface Igx‐ and Igλ ‐bearing B cells in adult CBA/Tufts, CBA/N and nude mice. Hence, serum ratios may reflect differences at the level of B cell triggering. Two possible explanations for these differences are discussed. Igx and Igλ may be expressed on functionally distinct B cell subsets. (For instance Igλ ‐producing cells might be readily triggered by T1 antigens whereas Igx‐producing cells are more dependent on T cell signals. Such functional subsets could be determined by light chain expression). Alternatively, cells producing Igx antibody are selected for because they have a higher affinity for antigen. If so, triggering of cells producing high affinity Igx or their subsequent selection is T cell‐dependent.