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Studies for vaccine and human therapeutic Ab development in cynomolgus monkeys (cynos) are influenced by immune responses, with Ab responses playing a significant role in efficacy and immunogenicity. Understanding the nature of cyno humoral immune responses and characterizing the predominant cyno IgG types produced and the Fc–FcγR interactions could provide insight into the immunomodulatory effects of vaccines. Anti-drug Ab responses against human IgG therapeutic candidates in cynos may affect efficacy and safety assessments because of the formation of immune complexes. There is, however, limited information on the structure and function of cyno IgG subclasses and how they compare with human IgG subclasses in Fc-dependent effector functions. To analyze the functional nature of cyno IgG subclasses, we cloned four cyno IgG C regions by using their sequence similarity to other primate IgGs. The four clones, cyno (cy)IGG1, cyIGG2, cyIGG3, cyIGG4, were then used to construct chimeric Abs. The sequence features of cyno IgG subclasses were compared with those of rhesus monkey and human IgG. Our data show that rhesus monkey and cyno IgG C regions are generally highly conserved, with differences in the hinge and hinge-proximal CH2 regions. Fc-dependent effector functions of cyno IgG subclasses were assessed in vitro with a variety of binding and functional assays. Our findings demonstrate distinctive functional properties of cyno IgG subclasses. It is notable that human IgG1 was less potent than cyno IgG1 in cyno FcγR binding and effector functions, with the differences emphasizing the need to carefully interpret preclinical data obtained with human IgG1 therapeutics.

The transient receptor potential ankyrin 1 (TRPA1) channel has been implicated in different pathophysiologies that include asthma, cough, itch, and inflammatory pain. Agonists of TRPA1 such as mustard oil and its key component allyl isothiocyanate (AITC) cause pain and neurogenic inflammation in humans and pain behaviors in rodents. Hence, TRPA1 antagonists are being pursued as potential therapeutics. With the goal of generating monoclonal antibodies (mAbs) to human TRPA1 that could act as selective antagonists, we immunized mice with a variety of antigens expressing TRPA1 channels. After generation of hybridomas, the hybridoma conditioned media were screened to identify the mAbs that bind TRPA1 channels by a flow cytometry assay utilizing U2OS or Chinese hamster ovary (CHO) cells stably expressing TRPA1. The purified IgGs from the hybridomas that showed selective binding to TRPA1 were evaluated for antagonism in agonist-induced 45 Ca 21 uptake assays using CHO-TRPA1 cells. Several of the mAbs showed concentration-dependent inhibition of AITC and cold (4°C) activation of TRPA1. The most potent mAb, 2B10, had IC 50 values of approximately 260 and 90 nM in the two assays, respectively. These antagonist mAbs also blocked osmotically activated TRPA1 as well as activation by an endogenous agonist (4-oxo-2-nonenal). In summary, we generated mouse mAbs against TRPA1 that act as antagonists of multiple modes of TRPA1 activation.

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It has been well-documented that the terminal sugars of Fc glycans can play a critical role in the safety and efficacy of therapeutic monoclonal antibodies (mAbs). However, many of the effects of highly heterogeneous Fc glycan structures have yet to be fully characterized. Different glycosylation patterns can affect Fcdependent activities such as the ability of mAbs to bind Fcγ receptors (FcγRs) on the effector cell surface, which is critical to immune effector functions such as antibody dependent cellular cytotoxicity (ADCC).Previous studies on the impact of sialic acid in the Fc glycan on ADCC has not resulted in consistent conclusions. In our study we tested sialic acid enriched species from a chimeric murine/human kappa light chain IgG1 (mAb1) with known FcγRIIIa binding and ADCC activities. These enriched species contained up to a four-fold increase in sialic acid-containing glycans relative to the typical levels present in therapeutic mAbs, along with other attributes such as oxidized and deamidated species. The ADCC analysis of sialylated