Infection with Neisseria gonorrhoeae (Gc) is characterized by an influx of neutrophils to the site of infection. Neutrophils express activating and inhibitory receptors to fine-tune immune responses. Carcinoembryonic antigen-related cell adhesion molecule 3 (CEACAM3) is one of the activating receptors that is constitutively expressed on the human neutrophil surface and transmits signals through its immunoreceptor tyrosine-based activation motif (ITAM). CEACAM3 can recognize some members of the opacity-associated (Opa) protein family on the bacterial surface, which leads to phagocytosis and bacterial killing. Even though neutrophils have multiple mechanisms to clear bacteria, Gc have evolved ways to evade killing by neutrophils. Previous work by our laboratory (Cardenas et al., 2024) has shown that one-way Gc can dampen neutrophil activation and antimicrobial activity is by engaging Sialic acid-binding immunoglobulin-type lectins (Siglecs), which possess an immunotyrosine-based inhibitory motif (ITIM) in their cytoplasmic domain. Gc engages Siglecs via sialylation of its lipooligosaccharide (LOS), by scavenging the sialic acid precursor cytidine-5′-monophosphate-N-acetylneuraminic acid (CMP-NANA) from the host using its LOS sialyltransferase enzyme (Lst). However, the molecular mechanisms governing sialic acid-mediated manipulation of neutrophils are not yet known. We hypothesize that binding of sialylated Gc to inhibitory Siglecs triggers downstream signaling cascades that interfere with CEACAM3-dependent signaling, ultimately dampening neutrophil activation. Since neutrophils have a short life span and are terminally differentiated cells, to test this hypothesis, we generated stable Chinese Hamster Ovary (CHO) cell lines that express CEACAM3, alone or with wild-type or ITIM-mutant (signaling-deficient) Siglec9. We found that sialylation does not affect the binding of Opa-expressing Gc to Siglec9- and CEACAM3-bearing CHO cells. Currently, we are using these cell lines to uncover how inhibitory Siglec activation affects the signaling cascade downstream of CEACAM3 that is elicited by Gc infection, including phosphatidylinositol 3′-kinase (PI3K), phospholipase C-gamma (PLC), and mitogen-activated protein kinases (MAPKs). Findings utilizing this model system will be confirmed in primary human neutrophils. These studies will dissect the mechanism by which sialylated Gc engagement of inhibitory Siglecs dampens neutrophil activation, enabling Gc survival in the face of the human innate immune response.