CRISPR-Engineered B Cells Dampen Autoimmune Responses in Mice

B cells have enormous potential in the field of immunotherapy. By engineering B cells to express specific antibodies, researchers can use them as an alternative to vaccines for infectious diseases and circumvent issues associated with the production and storage of antibodies.¹ However, these cells could also be used to tamp down overactive immune responses seen in autoimmune conditions, such as multiple sclerosis (MS), lupus, and rheumatoid arthritis.

Ragan Pitner, an immunologist at the University of Washington and the Seattle Children’s Research Institute is investigating this approach. During the “Engineered B-Cells as Therapeutic Agents” session of the 2026 annual meeting of the American Society of Gene and Cell Therapy, Pitner discussed the application of engineered B cells to modulate immune responses in a mouse model of MS. “Multiple sclerosis is a neat model for this because B cells that accumulate within the meninges are known contributors to [the disease],” Pitner said.

Decoy-Mediated Suppression with Engineered Bregs

Regulatory B cells (Bregs) help orchestrate both innate and adaptive immune responses by secreting regulatory cytokines such as interleukin-10 and 35 and transforming growth factor beta. They also regulate the ability of other immune cells to present antigens and use their own antigen presentation machinery to modulate the activation and differentiation of helper T cells. Despite their potential, Bregs remain underutilized for therapeutic approaches.

“The approaches that leverage natural Bregs as a cell therapy are unlikely to succeed,” Pitner explained. “Primarily because Bregs are highly heterogeneous.” This heterogeneity in Breg phenotype and function contributes to various autoimmune disorders. Unlike other immune cells, such as regulatory T cells, the Breg phenotype is also largely transient, Pitner said, meaning they don’t necessarily stay inhibitory when they are sorted and stimulated in the lab.

Despite these challenges, Bregs are an attractive option for cell therapy because “In the people for whom Bregs would be the most useful, like people with autoimmune disease, [Bregs] are actually deficient,” Pitner added.

To create Bregs that could modulate immune responses, Pitner and his colleagues, including his mentor, immunologist David Rawlings of the Seattle Children’s Hospital, developed a technique they call decoy-mediated suppression. The team genetically edited cultured B cells, preventing their maturation into antibody-secreting cells, then primed these gene-edited B cells with their antigens and transplanted them into mice immunized with the corresponding antigens.

This resulted in the B cells expanding and dominating sites of B cell maturation, dulling the immune response to immunization.³ “If you take this a step further, you ought to be able to put in a regulatory cargo to then take advantage of this antigen presentation, prevent the differentiation of more active inflammatory subsets like [pro-inflammatory T helper 1 and T helper 17 cells], and perhaps drive regulatory T cell differentiation,” said Pitner.

Testing Engineered Bregs in a Mouse Model of Multiple Sclerosis

Next, the team wanted to explore the effects of this approach in a mouse model of MS. They injected mice with myelin oligodendrocyte glycoprotein (MOG), a peptide that causes encephalitis and demyelination, which are hallmarks of MS. Pitner and his colleagues performed CRISPR editing in the B cells to prevent their maturation and insert regulatory cargo.

The team found that these engineered Breg cells could successfully suppress disease-associated T cells, indicating potential in the treatment of autoimmune diseases. Finally, they investigated whether the edited Bregs could also respond to the production of antigens during autoimmune damage, such as myelin shedding. “These engineered antigen-specific B cells are preferentially expanded and retained in response to autoimmune tissue damage,” Pitner said about their currently unpublished data. The team is continuing to investigate the efficacy of the approach in models of MS.