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Publication Date

11-3-2014

Keywords

tumor immunity, anti-inflammatory, NY-ESO-1, immunoglobulin G, glycosylation, sialic acid, dendritic cells, melanoma

Abstract

Purpose: We tested the hypothesis that different glycoforms of antibodies from patients with metastatic melanoma have different functional effects on human dendritic cell differentiation and maturation.

Methods: Antibodies to the cancer antigen NY-ESO-1 were affinity-purified from patients with melanoma and further fractionated into different glycoforms by lectin chromatography. Sialic acid-rich and sialic acid-poor fractions of these immunoglobulin G antibodies (IgG) were added to dendritic cell cultures during both differentiation and maturation, and the resulting cellular messenger RNA (mRNA) and culture supernatants were tested by microarray and enzyme-linked immunoassay for molecules related to inflammatory pathways.

Results: We identified unique mRNA and secreted protein signatures that were induced by different glycoforms of IgG during dendritic cell differentiation and maturation. Among the variety of mRNA and proteins induced by the sialic acidrich IgG fraction, we found a dramatic increase in levels of the melanoma growth factor CXCL1.

Conclusions: Our findings support the concept that alternate glycoforms of IgG induce differing functional programs of dendritic cell differentiation and maturation. The data also support the concept that the functional phenotype of IgG is related to glycosylation. Thus, subtle changes in glycan structure can change the effector function of IgG from an inflammatory to an anti-inflammatory program. This work highlights the importance of the interface between tumors and the immune system, revealing a potential explanation as to why tumors persist and progress despite potent immune responses against them.

Online Appendix 1 (14-021).pdf (58 kB)
Data obtained during differentiation.

Online Appendix 2 (14-021).pdf (58 kB)
Data obtained during maturation.

Online Appendix 3 (14-021).pdf (68 kB)
Venn diagrams illustrating dramatic differences in the effects of Sia+ and Sia- IgG populations on inflammatory mRNA during dendritic cell differentiation and maturation. The Sia+ fraction of IgG was responsible for the vast majority of genes either up- or downregulated during both differentiation and maturation, whereas the Sia- fraction affected only a small number of genes. Also, there was little overlap induction (IL-12A mRNA) in the functional activities of the different Sia fractions. Under conditions of maturation, the Sia- fraction was essentially inert in terms of mRNA changes compared to control, whereas the Sia+ fraction showed a predominantly downregulatory influence on multiple inflammatory mRNA.

Online Appendix 4 (14-021).pdf (59 kB)
Venn diagrams illustrating limited overlap of the cytokines and chemokines secreted during dendritic cell differentiation and maturation. There is a reciprocal relationship of IL-6 and CCL-5 protein expression during differentiation, as the Sia+ fraction appears to augment their production whereas the Sia- fraction appears to dampen them. It is noteworthy that while the Sia+ fraction appears to augment CCL-5 and IL-6 production during differentiation, it appears to blunt expression of both molecules during maturation.