Can persistent Borrelia antigens sustain immune signaling and inflammatory burden, while antibody positivity alone cannot prove it?

Persistent Borrelia burgdorferi material is a biologically credible contributor to inflammation in selected post-treatment settings, but the evidence is strongest for local joint disease—not for a generalized systemic process inferred from blood tests or serology.

Clinical and mechanistic evidence

• In treated Lyme arthritis, B. burgdorferi peptidoglycan has been detected in synovial fluid after antibiotics, together with proinflammatory mediators. This retained material can activate human peripheral blood mononuclear cells through innate pathways including NOD2.
• The synovial inflammatory milieu—including TNF-α, IL-1β, IFN-γ, CXCL9/10, and CCL4—is consistent with persistent local immune activation. It does not by itself demonstrate viable ongoing infection.
• Continued antigen availability could support antigen processing and presentation and thereby maintain adaptive immune activity. However, direct longitudinal human evidence linking antigen quantity to antigen-specific T-cell activation is not established.
• A systemic contribution remains plausible rather than demonstrated. Findings such as elevated CCL19 and persistent inflammatory/immune-trafficking transcriptional changes in some post-treatment cohorts have not been prospectively tied to measured retained Borrelia antigen and are not a validated systemic signature.

Meaning of antibody positivity

• Positive Borrelia IgG—and sometimes IgM—may persist for years or decades after eradication, reflecting immune memory rather than retained antigen, active infection, or current inflammation.
• Serology does not measure tissue antigen, innate-cell activation, cytokines, T-cell activity, or systemic inflammatory burden. Cross-reactivity, rheumatoid factor, and low pretest probability further limit interpretation; isolated IgM after >30 days of symptoms is particularly vulnerable to misinterpretation. One low-prevalence cohort reported an overall positive predictive value of 17% for two-tier testing.

Bottom line

• Retained Borrelia antigen can sustain localized innate inflammation in Lyme arthritis; adaptive and systemic effects remain biologically plausible but unproven. Antibody positivity alone cannot establish any of these processes.