Serum IgG Subclass May Be Indicator of Treatment Effect in Multiple Myeloma

Exploring whether subclasses of serum immunoglobulin G (IgG) have implications for how patients with multiple myeloma respond to treatment, researchers of a recent paper have identified a specific subclass they say may be particularly helpful in predicting treatment efficacy.

Across serum and urine samples from 560 patients, the researchers found that among subclasses, IgG1 expression was most prominent in the disease. Compared against controls, expression of IgG1 was increased by over 25% (26.38%) in patients with multiple myeloma while IgG2 was increased by 6.09%, IgG3 by 8.12%, and IgG4 by 4.64%. Notably, the researchers observed that expression of IgG1 changed significantly before, throughout, and following treatment.

They also found that concentrations of κ-LC and λ-LC were increased in serum samples by 27.5% and 26.43%, respectively. In urine samples, concentration of κ-LC were increased by up to 65%.

“Our study made interesting findings that IgG, IgG1, IgG2, IgG3, IgG4, κ-LC, and λ-LC, especially IgG1, κ-LC, and λ-LC, showed great changes in the process of treatment, that is, before, during, and after treatment. Therefore, these factors could be considered as prognostic factors, even as potential biomarkers for treatment effects for multiple myeloma,” wrote the researchers.

The researchers noted that not enough patients were followed to determine the correlation of IgG subclasses with overall and progression-free survival. As a result, the group called for more prospective studies to further describe the impact on treatment effect and characterize the effect on survival outcomes.

Observations in the peripheral blood from 57 patients were also made. Compared with healthy controls, proportions of CD3+CD4+, CD4+/CD8+, and CD3−CD19+ were significantly decreased in patients with multiple myeloma. Meanwhile, proportions of CD3+CD8++ and CD16+CD56+ cells were significantly increased. Notably, CD3+CD4+, CD4+/CD8+ ratio, and CD3+CD8+ essentially normalized after treatment, suggesting that measuring T cell subsets can offer insights about disease status.

“We also further measured the immune cell-related cytokines in serum of patients with multiple myeloma,” described the researchers. “In serum of 57 patients, we found that IL-4, IL-6, IFN-c, and TNF-α significantly increased in multiple myeloma compared with healthy control, especially IL-6 and IFN-c. However, IL-2 also increased in serum with P value <0.0762. In addition, C-reactive protein (CRP) significantly upregulated in serum of patients with multiple myeloma compared with healthy controls.”

According to the researchers, their finding that NK cells were significantly higher among patients with multiple myeloma compared with controls was consistent with previous findings. They added that immune self-stabilization was still possible in the early stages of disease while NK cell function was significantly impaired in the progressive stage of disease, indicating that these patients have “extensive immunodeficiency.”

Reference

Yin J, Qiu J, Zhang Z, Feng B, Shi J, Zheng D. Analysis of serum IgG1 to predict progression and therapeutic effect in patients with multiple myeloma. J Oncol. Published online March 17, 2022. doi:10.1155/2022/8628781