B Cell Subset Changes During Ovarian Cancer

Abstract

Early biomarkers of ovarian cancer (OvCa) are needed for timely disease detection. Monitoring alterations in the immune system might be informative in this regard. To study humoral immunity during OvCa, we transplant murine epithelial carcinoma cells (ID8) into the peritoneal cavity (PerC). As the PerC is enriched for B1 cells, we assessed B cell subset composition via flow cytometry. As OvCa developed PerC B1 cells were lost while B2 cells persisted in the PerC and spleen (SP). This difference might reflect that self-reactive B1 cells have a role in housekeeping and lack progenitors in adult mice. We tested the latter hypothesis by monitoring transitional (T) B cells, and found the T1, T2, and T3 subsets were markedly reduced in late stage disease, suggesting depletion of B1 B cells, as opposed to expansion of B2 B cells. Intriguingly, marginal zone B cells (MZB) expanded early then contracted as OvCa progressed. We speculate that housekeeping burden grows with OvCa progression and the cells most associated with this vital homeostatic process, notably B1 and MZB cells, are most at risk. These findings highlight the disruption of B cell biology in mice challenged with OvCa, and may help to inform strategies to develop biomarkers for the disease.