This might be a question best suited to @Jonathan Edwards but maybe others can answer as well. What does it mean when a person has antibodies to an antigen but they're not high enough to garner a positive or equivocal result? Examples: AChR Blocking Abs, Serum Your value: 15% Interpretation: Negative: 0 - 25% Borderline: 26 - 30% Positive: >30% GM-1 Ganglioside IgG Antibody Your value: 8 IV Interpretation: Negative: <29 IV Equivocal: 30-50 IV Positive: 51-100 IV In both of these examples, the antibodies aren't zero but they're not high enough for a diagnosis either. So why do these antibodies exist? What do they mean?