The effect of solvent environment on the conformation and stability of human polyclonal IgG in solution

Árpád Szenczi, J. Kardos, György A. Medgyesi, P. Závodszky

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

Stability of therapeutic IgG preparations is an important issue as adequate efficacy and safety has to be ensured throughout a long shelf life. To this end, denaturation and aggregation have to be avoided. In many cases sugars are applied for stabilizing IgG in relatively high concentration (5-10%). However, certain sugars (sucrose, maltose) are responsible for adverse effects including renal failure. In this work we reassessed the effect of pH and stabilizers to optimize the solvent environment and minimize the amount of additives without endangering quality and stability. Since both biological function and aggregation depend on the conformational properties of individual IgG molecules, two sensitive and rapid physical methods were introduced to assess conformational changes and structural stability as a function of pH and addition of standard stabilizers. It was observed that the conformational stability decreases with decreasing pH, while the resistance against aggregation improves. The optimum pH range for storage is 5.0-6.0, as a compromise between conformational stability and the tendency for oligomerization. Intriguingly, additives in physiologically acceptable concentration have no effect on the thermal stability of IgG. On the other hand, glucose or sorbitol, even at a concentration as low as 1%, have significant effect on the tertiary structure as revealed by near-UV-CD spectroscopy, reflecting changes in the environment of aromatic side-chains. Although, 0.3% leucine does not increase conformational stability, it decreases the aggregation tendency even more efficiently than 1% glucose or sorbitol. Both pH and storage temperature are decisive factors for the long-term stability of IgG solutions. An increase in the dimer content was observed upon storage at 5°C which was partly reverted upon incubation at 37°C. Storage at temperatures higher than 5°C may help to maintain an optimal proportion of dimers. Regarding the known side effects, and their limited stabilizing capacity at low concentration, it is advisable to omit sugars at intravenous immunoglobulin (IVIG) formulation. Hydrophobic amino acids give promising alternatives.

Original languageEnglish
Pages (from-to)5-14
Number of pages10
JournalBiologicals
Volume34
Issue number1 SPEC. ISS.
DOIs
Publication statusPublished - Mar 2006

Fingerprint

Conformations
Immunoglobulin G
Sorbitol
Agglomeration
Sugars
Sugar (sucrose)
Dimers
Glucose
Temperature
Maltose
Intravenous Immunoglobulins
Leucine
Stabilizers (agents)
Renal Insufficiency
Oligomerization
Sucrose
Denaturation
Spectrum Analysis
Hot Temperature
Safety

Keywords

  • Circular dichroism
  • Differential scanning calorimetry
  • Immunoglobulin G

ASJC Scopus subject areas

  • Immunology
  • Microbiology
  • Infectious Diseases

Cite this

The effect of solvent environment on the conformation and stability of human polyclonal IgG in solution. / Szenczi, Árpád; Kardos, J.; Medgyesi, György A.; Závodszky, P.

In: Biologicals, Vol. 34, No. 1 SPEC. ISS., 03.2006, p. 5-14.

Research output: Contribution to journalArticle

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