FROM NEW ENGLAND JOURNAL OF MEDICINE

Clonal immunoglobulin reactive to lyso-glucosylceramide (LGL1), which is elevated in Gaucher disease, was found in patients with Gaucher disease as well as in one third of patients with sporadic monoclonal gammopathies.

Antigen-specific immunoblots showed that 17 of 20 patients with Gaucher disease had clonal immunoglobulin against LGL1, researchers reported ( N Engl J Med. 2016 Feb 10 ).

Analysis of immunoglobulin gene mutations has provided evidence for antigen-driven clonal expansion of plasma cells in multiple myeloma and monoclonal gammopathy of undetermined significance (MGUS), but the underlying antigens remained unknown. Myeloma risk is increased with lipid disorders such as Gaucher disease and obesity, suggesting lipid involvement in pathogenesis.

“These studies set the stage for newer approaches to lower the levels of these lipids in patients with Gaucher disease and others with precursors for myeloma. Potentially, this could be achieved with drugs or lifestyle changes to reduce the levels of lipids to lower the risk of cancer,” senior author Dr. Madhav Dhodapkar , chief of hematology at Yale Cancer Center, New Haven, Conn., said in a press release.

All six mouse models with Gaucher-like disease had clonal immunoglobulin against LGL1. Gaucher disease–associated gammopathy in mouse models can be targeted by the reduction of the underlying antigen. Feeding eliglustat to the mice with clonal immunoglobulins reduced anti-LGL1 antibodies detected by immunoblot and reduced clonal immunoglobulin in vivo.

Dysregulated lipids are sometimes present in sporadic myeloma, and M spikes on LGL1-specific blotting were LGL1-reactive in 22 of 66 patients (33%). These clonal immunoglobulins also were cross reactive to lysophosphatidylcholine. Patients with polyclonal gammopathies not associated with Gaucher disease did not react to the lysolipids.

“Understanding the antigenic reactivity of clonal immunoglobulin not only has direct implications for antigenic origins of myeloma but also may lead to new strategies to prevent or treat clinical cancer by targeting the underlying antigen,” wrote Shiny Nair , Ph.D., of Yale University and colleagues.

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