Figure 3.

Regeneration after immunoablative therapy of ACPA-IgG autoantibodies with low avidity. (a) Low avidity of antibodies against anti-cyclic citrullinated protein (ACPA)-IgG (solid lines) before and after immunoablative therapy when autoimmunity is reactivated with rising levels of ACPA-IgG (dotted lines) in the three 'ACPA responders'. Levels below the detection limit were arbitrarily assigned a value of 4 arbitrary units (AU)/ml to optimize the graphical representation. Thick lines represent mean values. (b) Avidity of ACPA-IgG (solid lines) before and after immunoablative therapy in the three 'ACPA nonresponders', in whom, despite relatively stable ACPA-IgG levels (dotted lines), reactivation of autoimmunity was accompanied by the avidity maturation of ACPA-IgG autoantibodies. Thick lines represent mean values. (c) Avidity of tetanus toxoid (TT)-IgG (solid lines) before and after immunoablative therapy in four patients. Increasing levels of TT-IgG (dotted lines) after repeated TT immunizations (see Materials and methods) were accompanied by stably high avidity of TT-IgG, indicative of an intact humoral recall response despite immunoablative therapy. Thick lines represent mean values. DMARD, disease-modifying antirheumatic drug; NaSCN, sodium thiocyanate.