Sialylated CD43 is a glyco-immune checkpoint for macrophage phagocytosis

Jooho Chung; Mounica Vallurupalli; Sarah Noel; Gail Schor; YuhJong Liu; Celeste Nobrega; Jonathan Perera; Ewa Wrona; Margaret Hu; Yunkang Lin; David Wei Wu; Maria Saberi; Ilario Scapozza; Aidan Cruickshank; Elliot C. Woods; Cun Lan Chuong; Filippo Birocchi; Ashwin V. Kammula; Omar I. Avila; Mustafa Kocak; John G. Doench; Dean J. Procter; Lindsey Thornton; Andrew Mark Brunner; Eric P. Winer; Daniel J. DeAngelo; Jacqueline Suen Garcia; Richard Maury Stone; Russell William Jenkins; Marcela Valderrama Maus

doi:10.1101/2025.05.05.652090

Cancer BiologybioRxivMay 5, 2025

Preprint

Sialylated CD43 is a glyco-immune checkpoint for macrophage phagocytosis

Jooho Chung iD, Mounica Vallurupalli iD, Sarah Noel iD, Gail Schor iD, YuhJong Liu, Celeste Nobrega, Jonathan Perera iD, Ewa Wrona iD, Margaret Hu, Yunkang Lin iD, David Wei Wu iD, Maria Saberi, Ilario Scapozza iD, Aidan Cruickshank, Elliot C. Woods iD, Cun Lan Chuong iD, Filippo Birocchi iD, Ashwin V. Kammula iD, Omar I. Avila iD, Mustafa Kocak iD, John G. Doench iD, Dean J. Procter iD, Lindsey Thornton, Andrew Mark Brunner iD, Eric P. Winer iD, , Robert T. Manguso iD

Abstract

Macrophages in the tumor microenvironment exert potent anti-tumorigenic activity through phagocytosis. Yet therapeutics that enhance macrophage phagocytosis have not improved outcomes in clinical trials for patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). To systematically identify regulators of phagocytosis, we performed genome-scale CRISPR knockout screens in human leukemia cells co-cultured with human monocyte-derived macrophages. Surprisingly, we found that whereas the classic "dont eat me" signal CD47 inhibited mouse macrophages, it did not inhibit phagocytosis by human macrophages. In contrast, the O-linked glycosylation and sialylation pathways were strong negative regulators of phagocytosis. In AML, the cell surface O-linked glycoprotein CD43 was the major effector of the O-linked glycosylation and sialylation pathways. Genetic deletion or antibody blockade of CD43 enhanced macrophage phagocytosis. This work highlights the importance of using human platforms to identify immune checkpoints, and nominates CD43 as a glyco-immune regulator of human macrophage phagocytosis.

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