Serum Antibody to Bovine Serum Albumin I

To evaluate the re lat ionship be tween tumor burden and c i rculat ing immune complexes (IC) in ch i ldren with neurob lastoma (NBL), we studied sera col lected at intervals from pat ients with d isseminated (Stage III or IV) NBL. Sera from 10 of 12 pat ients conta ined IC by the Raji cell assay at some time dur ing the first 9 to 11 months of the study. H igher IC levels were observed in sera of female patients. F lu id-phase C l q b inding tests detected IC in only 16% of sera. IC measurements by ei ther assay did not corre la te with tumor burden. However , serum IC levels, as measured by the Raji cell assay, cor re la ted signi f icant ly with serum ant ibody to bovine serum albumin (BSA) (rs = 0.54; p < 0 .001 , rs = r a s de termined by Spearman rank corre lat ion test). Measurement of ant i -BSA ant ibod ies in sera from the 1 2 patients, tested serial ly for c i rculat ing IC, and from five addit ional pat ients revealed that these had significantly h igher ant i -BSA activity than was found in sera from 1 3 age-matched controls. Sera from females also had relat ively high levels of ant i -BSA. Levels of an t ibody to bovine y-g lobul in and casein were not abnormal . Three sera with high IC levels ( > 8 0 0 /~g equivalents of hea t -aggregated IgG) and relat ively low ant i -BSA activity appeared to conta in " h i d d e n " ant ibod ies to BSA. These were demonst ra ted by measur ing the increase in the abil i ty of sera to bind 12~I-BSA after they had been brief ly acidi f ied and then neutra l ized in the p resence of the labeled BSA. The possib le re levance of these resul ts to the pa thophysio logy of NBL is d iscussed in l ight of ear l ier wo rk that repor ted that serum IC levels corre la te with the s tage of the d isease in NBL.