What evidence would distinguish humoral autoimmunity from innate Th17?

The short version: you need to look for autoantibodies in the serum and for IL-17 in the tissue, not the other way around.

The evidence that separates humoral autoimmunity from innate Th17-driven inflammation is straightforward in principle but often muddy in practice. Humoral autoimmunity leaves a signature in the blood: autoantibodies against specific self-antigens. The evidence records show this clearly for type 1 diabetes, where GAD65 autoantibodies appear in 70-80% of newly diagnosed patients and 80-90% of prediabetic individuals [2]. In Guillain-Barré syndrome, anti-ganglioside antibodies (GM1, GD1a) are the hallmark [9]. In the K/BxN mouse arthritis model, autoantibodies against glucose-6-phosphate isomerase drive the disease, and treatments that suppress germinal center B cells reduce those autoantibodies and prevent arthritis [8].

Innate Th17-driven inflammation, by contrast, does not require autoantibodies. It is driven by IL-17 produced by Th17 cells, γδ T cells, or innate lymphoid cells. The evidence records show IL-17 acting directly on tissue cells: in the temporomandibular joint, IL-17A upregulates chemokines like CXCL1 (49-fold), CXCL8 (24-fold), and CCL20 (15-fold) in synovial fibroblasts [17]. In a mouse model of periapical infection, P. gingivalis LPS drives IL-17-dependent local inflammation and systemic glucose intolerance, and IL-17 knockout mice are protected [13]. In spondyloarthritis models, IL-23 overexpression drives arthritis through IL-17-producing cells that are CD4-CD8-RORγt+, not through B cells or antibodies [14].

The key distinguishing evidence is what you measure and where. For humoral autoimmunity, you measure serum autoantibodies against known self-antigens. For Th17-driven inflammation, you measure IL-17 in the tissue or the responding cells, not in the serum. The evidence records do not contain a single study that directly compares these two pathways in the same cohort with the same antigen. That gap matters. When spike protein is elevated in exosomes but absent in plasma and immune cells, the question becomes whether the exosomes are carrying a self-antigen that triggers autoantibody production (humoral) or whether they are delivering a signal that activates IL-17-producing cells directly (innate Th17). The evidence records show that exosomes can carry both self-antigens [20] and viral antigens [22], so the cargo alone does not settle it.

My call: the evidence supports measuring serum autoantibodies against the spike protein or cross-reactive self-antigens to confirm humoral autoimmunity, and measuring IL-17 in tissue or exosome-stimulated cell cultures to confirm Th17-driven inflammation. Confidence: moderate, because no study in this retrieval directly tests both pathways in the same system with the same exosomal cargo.