Differences in the isoelectric focussing pattern of antibodies to human serum albumin eluted from an immunoadsorbent (HSA-sepharose) with thiocyanate ions.

Anti HSA-antibodies were isolated from HSA-sepharose by direct and stepwise elution with 0.5 M, 2.0 and 3.0 M KSCN at different pH values. The antibody fractions, especially those eluted stepwise, varied in their isoelectrofocussing pattern. Nearly all antibody molecules with an isoelectric point (PI) lower than 6.5 were eluted with 0.5 M KSCN. Application of increasing KSCN concentrations led to the recovery of antibody fractions showing a parallel shift in the PI to the region higher than 7.5. These differences were not correlated with differences in antibody avidity. The effect of KSCN does not seem to be restricted to the combining sites of the antibody. The dissociation of the antibody from the antigen is apparently facilitated by an interaction of KSCN with the remainder of the antibody molecule thereby influencing the overall net charge.