Senior Scientific Lead Abcam Ltd Cambridge, United Kingdom
Disclosure(s):
Emilie Stolarczyk, PhD: No relevant disclosure to display
Introduction/Rationale: Neutrophils are key modulators of tumor progression and immune responses. Ly6G-neutralizing antibodies are widely used to study neutrophil biology, yet their long-term depletion efficiency varies. We compared two anti-Ly6G [1A8] antibody formats -rat IgG2a and recombinant mouse IgG2c- in a KP intratracheal (KPi.t.) lung tumor model to assess sustained neutrophil depletion and tissue clearance.
Methods: KPi.t. mice (n = 3/group) were randomized into four treatment arms, anti-Ly6G [1A8] rat IgG2a or mouse IgG2c and corresponding isotype controls, and administered intraperitoneal injections of the indicated antibodies at 200μg per mouse every three days. Peripheral blood was collected on days 0, 3, and 12 to monitor neutrophil depletion. Mice were sacrificed on day 15, and blood and lung tissues were analyzed for CD11b⁺ Gr-1⁺ cells by flow cytometry.
Results: The recombinant mouse IgG2c anti-Ly6G [1A8] achieved robust and sustained depletion of circulating neutrophils throughout the 15-day study. In contrast, the rat IgG2a format showed partial recovery of CD11b⁺ Gr-1⁺ cells by day 12. Lung analysis revealed near-complete neutrophil clearance with mouse IgG2c, whereas rat IgG2a-treated mice retained 15 % parenchymal neutrophil CD11b+ Gr1+.
Conclusion: The mouse IgG2c anti-Ly6G [1A8] chimeric antibody (ab320708) demonstrated superior long-term efficacy compared to the rat IgG2a format. This optimized approach reduces injection frequency and hands on time whilst greatly improving animal welfare. It additionally enhances reliability in neutrophil depletion studies and supports deeper insights into neutrophil biology in cancer.
