Binding of cytokines to pharmaceutically prepared human immunoglobulin

• Published in: The Journal of clinical investigation 1993-11, Vol.92 (5), p.2533-2539
• Main Authors: SVENSON, M, HANSEN, M. B, BENDTZEN, K
• Format: Article
• Language: English
• Subjects: Animals; Antibodies - blood; Biological and medical sciences; Biological Products - immunology; Cytokines - immunology; Detergents - pharmacology; Humans; Immunoglobulin G - immunology; Immunomodulators; Interleukin-1 - immunology; Interleukin-6 - immunology; Medical sciences; Milk; Pharmacology. Drug treatments; Tumor Necrosis Factor-alpha - immunology
• ISSN: 0021-9738; 1558-8238
• DOI: 10.1172/jci116862

Pharmaceutically prepared IgG, pooled from sera of over 2,000 normal individuals, contained both monomeric and dimeric IgG. Each type of IgG bound 125I-labeled interleukin (IL)-1 alpha, IL-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha. Increased binding to IgG was observed if 125I-IL-1 beta was denatured by heating to 39 degrees C. However, the binding of both nondenatured and denatured 125I-IL-1 beta was not inhibited by unlabeled IL-1 beta. In contrast, binding of 125I-IL-1 alpha, 125I-IL-6, and 125I-TNF alpha was inhibited by the corresponding unlabeled cytokine. Papain-digestion of IgG abolished binding of 125I-TNF alpha but failed to influence the displaceable binding of 125I-IL-1 alpha and 125I-IL-6. 125I-TNF alpha was a mixture of trimeric and monomeric forms, the latter being the predominant form at lower concentrations. The apparent saturability of 125I-TNF alpha was explained by a higher nonspecific binding of monomeric than of trimeric 125I-TNF alpha to IgG. The amounts of cytokine antibodies in IgG preparations would contribute approximately 2 micrograms anti-IL-1 alpha IgG and 1 microgram anti-IL-6 IgG per kg body wt during high dose immune globulin therapy. In conclusion, pharmaceutical preparations of human IgG contain specific and neutralizing, high affinity antibodies against IL-1 alpha and IL-6, but not against TNF alpha or IL-1 beta. There are significant methodological pitfalls that hamper detection of IgG autoantibodies against cytokines.