Past work has demonstrated that the κ:λ ratio in serum immunoglobulins varies significantly among species. In murine systems it has been established that serum levels of immunoglobulins containing κ and λ light chains are present in concentrations of 95 and 5%, respectively. The experiments reported here were designed to determine the molecular basis for this unbalanced ratio. We examined spleens and Peyer's patches (PP) of CBA/J mice for the ratio of κ to λ for surface Ig expression, mRNA accumulation, transcription and in vitro translation. Studies of the levels of B-cells expressing κ and λ revealed the percentages to be similar to the protein concns in serum (90% κ +, 10% λ +). However, further analysis of light chain mRNA accumulation and nuclear transcription revealed ratios of κ:λ only slightly greater than 1.0 in most cases. In addition, in vitro translation of B-cell-derived mRNA demonstrated greater translation of κ chains relative to λ, though clearly not totally sufficient to provide a serum ratio of 95:5. The results suggest that the low concn of serum λ relative to κ in the mouse is most likely due to post-translational events such as inefficient protein processing, poor association with heavy chains, etc. In addition, these data support the hypothesis that λ-mRNA is present in some κ -bearing B-cells since λ-mRNA levels are higher than one would predict from a population of cells in which only 5% express surface λ chain protein.
ASJC Scopus subject areas
- Molecular Biology