Immunoglobulin G3 and immunoglobulin M isotype plasma levels are influenced by interleukin-1alpha genotype

Evaluation and validation of the prognostic value of anti-MDA5 IgG subclasses in dermatomyositis-associated interstitial lung disease

OBJECTIVE

To investigate the association between the anti-melanoma differentiation associated gene 5 (MDA5) IgG subclasses and prognosis of patients with dermatomyositis (DM)-associated interstitial lung disease (ILD).

METHODS

This retrospective study included 122 anti-MDA5 positive DM-ILD patients admitted from October 2017 to October 2020 as training cohort, and additional 68 patients from August 2014 to September 2017 as validation cohort. The levels of anti-MDA5 total IgG and IgG subclasses were measured using in-house enzyme-linked immunosorbent assays, and analysed in association with the patient prognosis.

RESULTS

In the training cohort, the concentrations of anti-MDA5 IgG1 and IgG3 in non-survivors were significantly higher than in survivors (P < 0.05), whereas there were no significant differences in the IgG2 and IgG4 levels. Kaplan-Meier survival analysis revealed that the levels of anti-MDA5 total IgG, IgG1 and IgG3 were associated with mortality (P < 0.05). Multivariate analysis revealed anti-MDA5 IgG1 >13 U/ml and anti-MDA5 IgG3 >11 U/ml were independent risk factors for death of DM-ILD patients (P < 0.05). Anti-MDA5 IgG1 was confirmed as an independent risk factor in the validation cohort, while anti-MDA5 IgG3 was not. Anti-MDA5 IgG1 showed greater discriminable power for patient prognosis (Youden index 0.494) than anti-MDA5 total IgG, IgG3, or the combination of IgG1 and IgG3 (Youden index 0.356, 0.32 and 0.447, respectively).

CONCLUSION

Anti-MDA5 IgG1 and IgG3 are significantly associated with poor prognosis in DM-ILD patients, and anti-MDA5 IgG1 is more efficient as a prognostic biomarker in DM-ILD patients.

Adaptive Immunity against Streptococcus pyogenes in Adults Involves Increased IFN-γ and IgG3 Responses Compared with Children

Each year, millions of people are infected with Streptococcus pyogenes, leading to an estimated 500,000 annual deaths worldwide. For unknown reasons, school-aged children have substantially higher infection rates than adults. The goal for this study was to provide, to our knowledge, the first detailed characterization of the human adaptive immune response against S. pyogenes in both children and adults. We report that all adults in our study, as well as most children, showed immunity against the two conserved group A streptococci (GAS) Ags, streptococcal C5a peptidase and immunogenic secreted protein. The response primarily consisted of three subsets of Th1 T cells, in which the TNF-α(+) and IL-2(+)TNF-α(+) subsets were most frequent. Humoral immunity was dominated by IgG1 and IgG3, whereas the Th2-associated IgG4 isotype was only detected at very low amounts. IgG3 levels correlated significantly with IFN-γ, but not with IL-5, IL-13, IL-17, or TNF-α. Interestingly, children showed a similar pattern of Ag-specific cytokine release, but displayed significantly lower levels of IgG3 and IFN-γ compared with adults. Thus, human immune responses against S. pyogenes consist of a robust Th1 cellular memory response in combination with IgG1/IgG3-dominated humoral immunity that increase with age. The significance of these data regarding both the increased GAS infection rate in children and the development of protective GAS vaccines is discussed.

IgG subclass profiles in infected HIV type 1 controllers and chronic progressors and in uninfected recipients of Env vaccines

We have studied IgG subclass responses to the HIV-1 proteins gp120, gp41, p24, and Tat in individuals who control their infection without using antiretroviral drugs (HIV-1 controllers; HC) or who progress to disease (chronic progressors; CP). We also measured IgG subclass titers to gp120 in vaccinated individuals. In all cases, the IgG1 subclass dominated the overall response to each antigen. The only IgG titer that differed significantly between the HC and CP groups was to the p24 Gag protein, which was higher in the HC group. IgG1 titers to both p24 and gp120 were significantly higher in the HC group, and IgG3 anti-gp120 antibodies, although rare, were detected more frequently in that group than in CP. Overall, significantly more patients had IgG2 antibodies to gp120 than to gp41. Antibodies to other IgG subclasses were infrequent and their frequency or titers did not differ between the two patient groups. Anti-gp41 and anti-Tat responses also did not correlate with immune control, and anti-Tat antibodies were infrequently detected. Although we found isotypic differences in IgG responses to HIV-1 antigens among vaccinees and the HC and CP individuals, there were no indications of differential T(H)1:T(H)2 polarization between the different groups.