An Evaluation of Elution Techniques in the Study of Immune Complex Glomerulonephritis

Abstract

Antigen and antibody from glomerular immune complex deposits in rabbits with experimental bovine serum albumin-(BSA) induced chronic serum sickness (CSS) were quantitated in eluates from kidneys in which a portion of the antigen and antibody had been radiolabeled. The largest quantities of ¹²⁵I BSA eluted with 1 M proprionic acid at pH 2.7 (86%) and 0.1 M borate buffer at pH 11.25 (80%). However, these buffers yielded less functional anti-BSA antibody than 0.02 M citrate buffer at pH 3.2 (344 µg/g kidney). Citrate buffer-eluted anti-BSA antibody was reactive in immunodiffusion, immunofluorescence, and radiolabeled BSA binding test systems, but complement fixation was impaired relative to chaotropic ion-eluted antibody. It was found that up to 75% of the eluted antibody was lost to further study by recombination with eluted BSA. This could be prevented by fractionation of the dissociated eluate before neutralization. IgG fractionated eluates were successfully fluorescein conjugated or radiolabeled for use as reagents. Elution of cryostat sections of CSS kidney was also studied; BSA, IgG, and complement (C3) eluted in parallel, and sub-microgram quantities of anti-BSA antibody were recovered.