Every cell in your body is covered in glycans, which are sugar chains stuck to proteins and lipids. Sialic acids often sit at the outer edge of that coat, like the last visible bead on a bracelet. Immune cells use receptors called Siglecs - short for sialic acid-binding immunoglobulin-like lectins - to inspect that sugary layer and decide whether to calm down, attack, or mind their business.
That matters because cancer loves a loophole. Tumors often pile on sialylated glycans and use them to push immune cells toward the cellular equivalent of "nothing to see here" (van Houtum et al., 2021; Läubli et al., 2022).
The problem is that Siglec biology has been messy. Different labs have reported different expression patterns and different binding preferences. That is not ideal when you are trying to turn these molecules into biomarkers or drug targets. It is also how entire research fields end up staring at the same sugar cube from five angles and arguing.
What this new atlas actually did
The new study by Leviatan Ben-Arye and colleagues tried to clean that up by profiling 14 functional human Siglecs across expression, binding behavior, and binding strength (Ben-Arye et al., 2026). They looked at RNA expression in blood immune cells, checked protein expression in spleen cells, and then tested Siglec binding across a large pile of glycan arrays and cell-based systems.
A few big patterns stood out.
First, Siglecs were broadly expressed in monocytes and dendritic cells, more restricted in NK cells and B cells, and basically absent in T cells at the mRNA level. So the receptors reading the sugar code are concentrated in the immune cells that patrol, sample, and regulate. The neighborhood watch, not the full stadium crowd.
Second, different Siglecs were picky in different ways. Binding changed depending on the exact sialic acid, the chemical decorations on it, the linkage, sulfation, and the molecular scaffold carrying it. Same family, very different taste in sugar.
Third, and maybe most interesting, the study emphasizes cis interactions. That means Siglecs often bind sugars on the same cell they sit on, not just on a neighboring cell. So these receptors are not only checking other cells' ID badges. They are also staring at their own reflection and adjusting their mood.
Why cancer people should care
This matters because the Siglec-sialic acid axis has become one of the more interesting side doors in immunotherapy. We spend a lot of time talking about PD-1 and CTLA-4. Fair. They earned the spotlight. But Siglecs may be part of another immune checkpoint layer, especially in myeloid cells such as macrophages and dendritic cells (Boelaars and van Kooyk, 2024).
Recent reviews make the same point from slightly different angles: glycans are not decoration, they are active regulators of immune behavior (Jame-Chenarboo et al., 2024; Nardini et al., 2024). If you do not know which Siglec is expressed where, what it binds, and how tightly it binds, drug design gets sloppy fast.
And the translational hints are already piling up. In colorectal cancer, a 2025 study linked the Siglec-14-LGALS3BP axis to tumor-associated macrophage polarization and worse outcomes (Lin et al., 2025). In pancreatic cancer, a 2026 study showed that blocking a Siglec-10 interaction restored macrophage phagocytosis in preclinical models (Saini et al., 2026). Translation: if tumors are using sugar-coated fake passports, researchers are getting better at spotting the lamination.
The catch, because there is always a catch
An atlas is not a cure. It is a field guide.
This paper does not prove that targeting a given Siglec will help patients. It does something more basic and more necessary. It tells the field which receptors live on which immune cells, what sugar features they notice, and how self-binding might muffle or tune those interactions before any therapy shows up.
That kind of map matters. If future drugs try to block a Siglec, strip tumor sialic acids, or use Siglecs as biomarkers, they will need this level of detail to avoid swinging at fog.
Cancer biology, as usual, has discovered a way to make sugars feel like espionage. But this time the spy manual got a lot better.
References
Ben-Arye SL, Schmidt EN, Jame-Chenarboo Z, et al. An atlas of human siglecs integrates expression, affinity, and cis/trans sialoglycan recognition profiles. Nature Communications. 2026;17:3866. DOI: https://doi.org/10.1038/s41467-026-71086-8
van Houtum EJH, Büll C, Cornelissen LAM, Adema GJ. Siglec signaling in the tumor microenvironment. Frontiers in Immunology. 2021;12:790317. DOI: https://doi.org/10.3389/fimmu.2021.790317
Läubli H, Nalle SC, Maslyar D. Targeting the Siglec-Sialic Acid immune axis in cancer: current and future approaches. Cancer Immunology Research. 2022;10(12):1423-1432. DOI: https://doi.org/10.1158/2326-6066.CIR-22-0366 PMCID: https://pmc.ncbi.nlm.nih.gov/articles/PMC9716255/
Boelaars K, van Kooyk Y. Targeting myeloid cells for cancer immunotherapy: Siglec-7/9/10/15 and their ligands. Trends in Cancer. 2024;10(3):230-241. DOI: https://doi.org/10.1016/j.trecan.2023.11.009
Jame-Chenarboo Z, Gray TE, Macauley MS. Advances in understanding and exploiting Siglec-glycan interactions. Current Opinion in Chemical Biology. 2024;80:102454. DOI: https://doi.org/10.1016/j.cbpa.2024.102454
Nardini E, Rodriguez E, van Kooyk Y. The tissue glycome as regulator of immune activation and tolerance mediated by C-type lectins and Siglecs. Seminars in Immunology. 2024;76:101913. DOI: https://doi.org/10.1016/j.smim.2024.101913
Lin KY, Jiang JK, Lai JI, et al. Siglec-14-LGALS3BP glycoimmune axis shapes tumor-associated macrophage polarization and confers poor outcome in colorectal cancer. npj Precision Oncology. 2025;9(1):398. DOI: https://doi.org/10.1038/s41698-025-01169-0 PMCID: https://pmc.ncbi.nlm.nih.gov/articles/PMC12706041/
Saini P, Mirji G, Islam SMS, et al. Targeting interactions between Siglec-10 and α3β1 integrin enhances macrophage-mediated phagocytosis of pancreatic cancer. Cancer Research. 2026;86(1):99. DOI: https://doi.org/10.1158/0008-5472.CAN-25-0977
Disclaimer: The image accompanying this article is for illustrative purposes only and does not depict actual experimental results, data, or biological mechanisms.