Immunoglobulins

Comparative Analysis of Laboratory-Scale Immunoglobulin G Purification Methods from Human Serum

Immunoglobulin G (IgG) purification is a critical process for evaluating its role in autoimmune diseases, which are defined by the occurrence of autoantibodies. Affinity chromatography with protein G is widely considered to be the optimal technique for laboratory-scale purification. However, this technique has some limitations, including the exposure of IgG to low pH, which can compromise the quality of the purified IgG. Here, we show that alternative methods for IgG purification are possible while maintaining the quality of IgG. Different techniques for IgG purification from serum were evaluated and compared with protein G-based approaches: Melon Gel, caprylic acid-ammonium sulfate (CAAS) precipitation, anion-exchange chromatography with diethylamino ethyl (DEAE) following ammonium sulfate (AS) precipitation, and AS precipitation alone. The results demonstrated that the purification yield of these techniques surpassed that of protein G. However, differences in the purity of IgG were observed using GeLC-MS/MS. The avidity of purified IgG against selected targets (SARS-CoV-2 and topoisomerase-I) was similar between purified IgG obtained using all techniques and unpurified sera. Our work provides valuable insights for future studies of IgG function by recommending alternative purification methods that offer advantages in terms of yield, time efficiency, cost-effectiveness, and milder pH conditions than protein G.

Staph’s Toxins IgE Antibodies and Its Relation to the Severity of Allergic Rhinitis

Background

Specific IgE against Staphylococcus can be found in approximately 40% of patients with allergies, also in patients without allergies because they may be sensitized. These antibodies are functional, and they can induce histamine release contributing to chronic pruritus which can worsen disease severity. The objective of this study was to compare levels of specific IgE against S. aureus toxins in those populations.

Methods

A cross-sectional, comparative non-blinded survey was made at the Regional Center for Allergy and Clinical Immunology. Ninety-nine adults between 18 and 70 years of age with allergic rhinitis (AR) and without allergic rhinitis (wAR) were recruited. A clinical history and demographic data, and allergic sensitization patterns to 35 aeroallergens were obtained, and participants were classified according to their severity using the Allergic Rhinitis and Its Impact on Asthma (ARIA) classification. Specific IgE levels were determined using ImmunoCAP™ 100 platform.

Results

The median age (IQR) of the participants was 23 (20–33.7); 56.2% were women. The most frequent comorbidities were asthma and obesity. Of the patients with AR, 46.7% were classified as mild intermittent and 25% as moderate persistent. IgE levels against staph toxins A, B, and TSST were significantly higher in the AR group vs the wAR group [median IQR 0.01 (0.01–0.03) vs. 0.01 (0–0.02), p = 0.01; 0.02 (0.01–0.03) vs. 0.01 (0–0.02), p= 0.02; 0.04 (0.02–0.09) vs. 0.01 (0–0.04), p=0.002, respectably]. A significant difference was found in serum IgE levels against Staph B toxin between severity subgroups.

Conclusion

People with AR have higher IgE levels against staph toxins A, B and TSST than wAR subjects. However, it is not possible declare that the IgE titers were related to disease severity.

Specific IgM, IgG and IgG1 directed against Toxoplasma gondii detected by flow cytometry and their potential as serologic tools to support clinical indirect fundoscopic presumed diagnosis of ocular disease

In the present study we evaluated the anti-Toxoplasma gondii immunoglobulin profiles of a group of 118 individuals living in an endemic area. The aim of the study was to select biomarkers to support the ophthalmological diagnosis of retinal/retinochoroidal scars presumably caused by T. gondii infection. Overall anti-T. gondii reactivity of the IgM, IgG, IgA, IgE and IgG subclasses was investigated by flow cytometry-based anti-fixed tachyzoite antibodies (FC-AFTA) in four groups of subjects, referred to as: i) TOXO(L)--seropositive patients with retinal/retinochoroidal scars presumably caused by T. gondii infection; these patients were further subdivided according to morphological aspects of their ocular scar lesions as A, B or C; ii) TOXO(NL)--seropositive patients without ocular scar lesions; iii) NEG(L)--T. gondii seronegative patients presenting retinal lesions; and iv) NEG(NL)--T. gondii seronegative without retinal lesions (negative controls). Our data demonstrated that anti-T. gondii IgG profiles were able to discriminate the mean reactivity of TOXO(L) from all other clinical groups. Analysis of anti-T. gondii immunoglobulin profiles revealed that IgM and IgG were good biomarkers capable of discriminating between individual reactivity in patients with retinal/retinochoroidal scars presumably caused by T. gondii infection [TOXO(L)] from those caused by other clinical conditions. Furthermore, anti-T. gondii IgG1 reactivity was able to discriminate TOXO(L) from all other clinical groups. In conclusion, the pre-selected IgM, IgG and IgG1 anti-T. gondii antibody subclasses were able to segregate both TOXO(L) and the other subgroups, including the scar lesion group types (A, B, C), from other clinical conditions. These results suggest the applicability of this technique in the clinical laboratory to detect putative biomarker for diagnosis of ocular lesions in T. gondii-infected patients. Studies in other areas implementing the methods described in the present study would be of value and enable evaluation of a system for classification of presumed ocular toxoplasmosis scar lesions. This classification would make comparative studies on ocular toxoplasmosis conducted in different regions around the world possible.

Genetic studies in Ecuador: acetylator phenotypes, red cell enzyme and serum protein polymorphisms of Shuara Indians

Population genetic studies of Shuara Indians in Ecuador are performed for GPT, AP, PGM1, Ak, EsD, 6-PGD, Hp, Gc, C3, Bg, ChE, Tf, Pi, Bf phenotypes, IgG, IgA, IgM, C3, C3-proactivator, C4 levels and acetylator phenotypes. Some systems having a polymorphism in many other populations showed a lack of some of those alleles in the population under study (C3, ChE, Tf, AK and almost absent 6-PGD, Bg, Bf).

Genetic polymorphism of C3 and serum levels of immunoglobulins, C3, C4 components of complement and C3-proactivator in four different populations of Afghanistan

The C3 phenotype distribution was studied in 4 different populations from Afghanistan. The gene frequencies of C3S allele were: Tajiks (0,8547), Pushtoons (0.8812), Hazaras (0.9036) and Osbeks (0.8530). These values were significantly higher than in European populations studied previously. No significant differences were found between the mean serum levels of C3, C4 and C3-proactivator among 4 population groups. A higher concentration of IgG, IgA and IgM was observed in Afghanistan sera than reported for Europeans.