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T-follicular helper (Tfh) cells are key drivers of antibodies that protect from malaria. However, little is known regarding the host and parasite factors that influence Tfh and functional antibody development. Here, we use samples from a large cross-sectional study of children residing in an area of high malaria transmission in Uganda to characterize Tfh cells and functional antibodies to multiple parasites stages. We identify a dramatic re-distribution of the Tfh cell compartment with age that is independent of malaria exposure, with Th2-Tfh cells predominating in early childhood, while Th1-Tfh cell gradually increase to adult levels over the first decade of life. Functional antibody acquisition is age-dependent and hierarchical acquired based on parasite stage, with merozoite responses followed by sporozoite and gametocyte antibodies. Antibodies are boosted in children with current infection, and are higher in females. The children with the very highest antibody levels have increased Tfh cell activation and proliferation, consistent with a key role of Tfh cells in antibody development. Together, these data reveal a complex relationship between the circulating Tfh compartment, antibody development and protection from malaria.

HIV-1 infection leads to chronic disease requiring life-long treatment and therefore alternative therapeutics, a cure and/or a protective vaccine are needed. Antibody-mediated effector functions could have a role in the fight against HIV-1. However, the properties underlying the potential beneficial effects of antibodies during HIV-1 infection are poorly understood. To identify a specific profile of antibody features associated with delayed disease progression, we studied antibody polyfunctionality during untreated HIV-1 infection in the well-documented Amsterdam Cohort Studies. Serum samples were analyzed from untreated individuals with HIV-1 at approximately 6 months (n = 166) and 3 years (n = 382) post-seroconversion (post-SC). A Luminex antibody Fc array was used to profile 15 different Fc features for serum antibodies against 20 different HIV-1 envelope glycoprotein antigens and the resulting data was also compared with data on neutralization breadth. We found that high HIV-1 specific IgG1 levels and low IgG2 and IgG4 levels at 3 years post-SC were associated with delayed disease progression. Moreover, delayed disease progression was associated with a broad and polyfunctional antibody response. Specifically, the capacity to interact with all Fc γ receptors (FcγRs) and C1q, and in particular with FcγRIIa, correlated positively with delayed disease progression. There were strong correlations between antibody Fc features and neutralization breadth and several antibody features that were associated with delayed disease progression were also associated with the development of broad and potent antibody neutralization. In summary, we identified a strong association between broad, polyfunctional antibodies and delayed disease progression. These findings contribute new information for the fight against HIV-1, especially for new antibody-based therapy and cure strategies. Author summary: Despite the availability of effective treatment, HIV-1 still causes significant mortality and morbidity across the globe. Alternative ways for protection or treatment against HIV-1 are needed. Antibody-mediated effector functions could potentially contribute to the effectiveness of novel approaches. However, we need more information on which antibody properties are associated with these potential beneficial functions of antibodies. Studying antibody responses during natural HIV-1 infection can provide guidance on this topic. This study identified several antibody properties that were associated with reduced HIV-1 disease progression in a large cohort of individuals with untreated HIV-1. High levels of IgG1 and low levels of IgG2 and IgG4, broad and polyfunctional antibodies and interaction with immune proteins FcyRs and C1q, were all associated with delayed disease progression. Subsequently, effective strategies against HIV-1 will likely require multiple different components, and the antibody properties described in this study may contribute to a more detailed bio-molecular roadmap for antibody-based strategies for HIV-1 prevention, therapy and cure. [ABSTRACT FROM AUTHOR]

Summary: Advances in antibody engineering are being directed at the development of next generation immunotherapeutics with improved potency. Hexamerisation of IgG is a normal physiological aspect of IgG biology and recently described mutations that facilitate this process have a substantial impact upon monoclonal antibody behavior resulting in the elicitation of dramatically enhanced complement‐dependent cytotoxicity, Fc receptor function, and enhanced antigen binding effects, such as targeted receptor agonism or microbe neutralization. Whereas the discovery of IgG hexamerisation enhancing mutations has largely focused on residues with exposure at the surface of the Fc‐Fc and CH2‐CH3 interfaces, our unique approach is the engineering of the mostly buried residue H429 in the CH3 domain. Selective substitution at position 429 forms the basis of Stellabody technology, where the choice of amino acid results in distinct hexamerisation outcomes. H429F results in monomeric IgG that hexamerises after target binding, so called "on‐target" hexamerisation, while the H429Y mutant forms pH‐sensitive hexamers in‐solution prior to antigen binding. Moreover, Stellabody technologies are broadly applicable across the family of antibody‐based biologic therapeutics, including conventional mAbs, bispecific mAbs, and Ig‐like biologics such as Fc‐fusions, with applications in diverse diseases. [ABSTRACT FROM AUTHOR]

IntroductionPassive administration of broadly neutralizing antibodies (BnAbs) reliably protects nonhuman primates from chimeric simian-human immunodeficiency virus (SHIV) challenge. A range of BnAbs delivered via either i.v. or mucosal routes consistently [...], A considerable body of evidence suggests that Fc-dependent functions improve the capacity of broadly neutralizing antibodies (BnAbs) to protect against and control HIV-1 infection. This phenomenon, however, has not been formally tested in robust cell-associated macaque simian-human immunodeficiency virus (SHIV) models with newer-generation BnAbs. We studied both the WT BnAb PGT121 and a LALA mutant of PGT121 (which has impaired Fc-dependent functions) for their ability to protect pigtail macaques from an i.v. high-dose cell-associated [SHIV.sub.SF162P3] challenge. We found that both WT and LALA PGT121 completely protected all 12 macaques studied. Further, partial depletion of NK cells, key mediators of Fc-dependent functions, did not abrogate the protective efficacy of PGT121 in 6 macaques. Additionally, in animals with established [SHIV.sub.SF162P3] infection, SHIV viremia levels were equally rapidly reduced by LALA and WT PGT121. Our studies suggest that the potent neutralizing capacity of PGT121 renders the Fc-dependent functions of the Ab at least partially redundant. These findings have implications for Ab-mediated protection from and control of HIV-1 infection.

Background: Sublingual immunotherapy (SLIT) for grass pollen allergy can modify the natural history of allergic rhinitis and is associated with increased allergen‐specific IgG4. IgG4 competitively inhibits functional IgE on the surface of effector cells, such as mast cells and basophils, from binding to allergens. To further understand the important role memory B‐cell (Bmem) responses play in mediating the beneficial effects of SLIT, we assessed changes in allergen‐specific Bmem subsets induced by SLIT for grass pollen allergy. Methods: Blood samples were collected twice outside the pollen season from twenty‐seven patients with sensitization to ryegrass pollen (RGP; Lolium perenne) and seasonal rhinoconjunctivitis. Thirteen received 4‐month pre‐seasonal SLIT for grass pollen allergy, and 14 received standard pharmacotherapy only. Single‐cell RNA sequencing was performed on FACS‐purified Lol p 1‐specific Bmem before and after SLIT from four patients, and significant genes were validated by flow cytometry on the total cohort. Results: Four months of SLIT increased RGP‐specific IgE and IgG4 in serum and induced two Lol p 1‐specific Bmem subsets with unique transcriptional profiles. Both subsets had upregulated expression of beta 1 integrin ITGB1 (CD29), whereas IGHE (IgE), IGHG4 (IgG4), FCER2 (CD23), and IL13RA1 were upregulated in one subset. There was an increase in the proportion of Lol p 1+ Bmem expressing surface IgG4, CD23, and CD29 after SLIT. Conclusions: A clinically successful 4 months course of SLIT for grass pollen allergy induces two transcriptionally unique Bmem fates. Associated changes in surface‐expressed proteins on these Bmem subsets can be used as early biomarkers for treatment effects. [ABSTRACT FROM AUTHOR]