B cell receptor light chain repertoires show signs of selection with differences between groups of healthy individuals and SLE patients

Abstract

We have developed a microarray to study the expression of L-chain V genes (VL genes) in healthy and SLE patient peripheral κ- and λ-sorted B cells. In all repertoires tested, one VL gene accounts for over 10% of all gene VL expression, consistent with positive selection acting on L-chains. While a few VL genes were highly expressed in all individuals, most VL genes were expressed at different levels. Some VL genes (5 out of a total of 78) were not detected. We attribute their absence from the repertoire to negative selection. Positive selection and negative selection were also found in SLE repertoires, but expression of VL genes was different; the differences point to less regulation of VL gene repertoires in SLE. Our data shows that VL gene expression is variable and supports a model where the L-chain repertoire is generated by both positive and negative selection on L-chains.

Molecular Basis of 9G4 B Cell Autoreactivity in Human Systemic Lupus Erythematosus

“…Moreover, the use of Vk-distal Jk genes or l L chains, more likely to be found in edited autoreactive B cells (56,60), did not correlate with lack of 9G4 autoreactivity. Instead, our findings are reminiscent of the traditional 3H9 mouse H chain, which imparts dominant anti-dsDNA autoreactivity that can be edited by very few L chains (59) and also with recent studies of the global B cell repertoire in SLE indicating lack of consistent positive or negative selection of individual L chains (70). Larger repertoire studies as well as more extensive testing of selected L chains expressed by 9G4 cells devoid of autoreactivity, currently underway in our laboratory, will be required to conclusively answer these important questions.…”

“…Our results conclusively demonstrate that, despite the L chain independence reported for IgM cold-agglutinins, L chains have a strong modifying potential of SLE 9G4 autoantibodies (70). However, contrary to previous studies indicating the ability of most L chains to edit the autoreactivity present in non-9G4 human B cells (41), most L chains tested failed to eliminate VH4-34-determined autoreactivity.…”

The analysis of clonal expansions in normal and autoimmune B cell repertoires

“…Table 1 shows four different experimental approaches that are used to analyse B cell clones. There are of course other approaches, such as Southern blotting of bulk repertoires [ 16 , 17 ], V gene arrays [ 18 ] and mass spectrometry of secreted antibodies [ 19 ], but we chose these four methods because they are the most frequently used.…”

Intrinsic bias and public rearrangements in the human immunoglobulin Vλ light chain repertoire

“…22 A more recent analysis by Weigert et al indirectly supports this same observation and similarly concludes the existence of an IGH-independent mode of IGL selection. 34 Using microarray profiling rather than deep sequencing, a set of IGL genes was observed to be uniformly highly expressed without IGH chain restriction (that is, IGH exhibiting a normally distributed CDR-H3 length spectratype), which they conclude is consistent with the positive selection of particular IGL chains, rather than clonal selection, independent of the IGH chain. Their results suggest that multiple overexpressed IGL chains might pair promiscuously with IGH chains.…”