Intrathecal K free light chain synthesis in multiple sclerosis at clinical onset associates with local IgG production and improves the diagnostic value of cerebrospinal fluid examination.

BACKGROUND: The pathological significance and the diagnostic usefulness of intrathecal κ and λ free light chain (FLC) synthesis in Multiple Sclerosis (MS) are debated. METHODS: Paired cerebrospinal fluid (CSF) and serum specimens from 70 relapsing remitting MS (RRMS), 40 with and 30 without CSF restricted IgG Oligoclonal Band (IgGOB), and 37 from healthy controls (HC) were analyzed. IgG, IgM, κFLC and λFLC concentrations and indexes were evaluated. All RRMS performed MRI to estimate white and grey matter (WM) pathology. RESULTS: In HC, no intrathecal κ or λ FLC synthesis was found, and κFLC and λFLC Indexes were reciprocally correlated (r = 0.67, p < 0.001). In RRMS, intrathecal κFLC or λFLC synthesis was demonstrated in respectively 66% and 43% of the cases, the Qκ/λ ratio was significantly higher compared to HC (17.0 ±â€¯31.3 vs 0.79 ±â€¯0.20, p < 0.001) and the correlation between κFLC Index and λFLC Index was weak (r:0.38, p < 0.05). Intrathecal IgG synthesis was associated with κFLC Index (IgG Index: r2 = 0.53, ß = 0.73, p < 0.001; IgGLOC: r2 = 0.37, ß = 0.61, p < 0.001; IgGIF: r2 = 0.69, ß = 0.83, p < 0.001), but not with λFLC Index, while intrathecal IgM synthesis correlated with λFLC Index (IgM Index: r = 0.41, p < 0.001; IgMLOC: r = 0.34, p < 0.005; IgMIF: r = 0.45, p < 0.001), but not with κFLC Index. 26% of RRMS patients without CSF-restricted IgGOB had increased κFLCLOC. Finally, no associations were observed between any CSF and MRI parameters. CONCLUSIONS: The demonstration of intrathecal κFLC synthesis may further improve the diagnostic usefulness of CSF examination in RRMS. The marked increased in Qκ/λ further suggests a deregulated B-cell activation in MS pathology.

Development of neutralizing scFv-Fc against botulinum neurotoxin A light chain from a macaque immune library.

Botulinum toxins (BoNTs) are among the most toxic substances on earth, with serotype A toxin being the most toxic substance known. They are responsible for human botulism, a disease characterized by flaccid muscle paralysis that occurs naturally through food poisoning or the colonization of the gastrointestinal tract by BoNT-producing clostridia. BoNT has been classified as a category A agent by the Centers for Disease Control, and it is one of six agents with the highest potential risk of use as bioweapons. Human or human-like neutralizing antibodies are thus required for the development of anti-botulinum toxin drugs to deal with this possibility. In this study, Macaca fascicularis was hyperimmunized with a recombinant light chain of BoNT/A. An immune phage display library was constructed and, after multistep panning, several scFv with nanomolar affinities that inhibited the endopeptidase activity of BoNT/A1 in vitro as scFv-Fc, with a molar ratio (ab binding site:toxin) of up to 1:1, were isolated. The neutralization of BoNT/A-induced paralysis by the SEM120-IID5, SEM120-IIIC1 and SEM120-IIIC4 antibodies was demonstrated in mouse phrenic nerve-hemidiaphragm preparations with the holotoxin. The neutralization observed is the strongest ever measured in the phrenic nerve-hemidiaphragm assay for BoNT/A1 for a monoclonal antibody. Several scFv-Fc inhibiting the endopeptidase activity of botulinum neurotoxin A were isolated. For SEM120-IID5, SEM120-IIIC1, and SEM120-IIIC4, inhibitory effects in vitro and protection against the toxin ex vivo were observed. The human-like nature of these antibodies makes them promising lead candidates for further development of immunotherapeutics for this disease.