ENGS 88 Honors Thesis (AB Students)

Degree Program

A.B.

Year of Graduation

2021

Faculty Advisor

Margaret Ackerman

Document Type

Thesis (Senior Honors)

Publication Date

Spring 6-7-2021

Abstract

Infections are responsible for over half a million neonatal deaths every year (Lawn et al., 2014). Thus, there is huge interest in leveraging maternal immunization against infectious diseases to grant fetal protection during its development through the vertical transferring of IgG antibodies, the only Ig subclass that can significantly cross the placental barrier. Studies about vertical immunization rely on in-vitro models to extrapolate physiological conditions of the human placenta. The BeWo Transwell model (Bode et al., 2006) presents itself as a reliable model to mimic the transplacental transport mechanism of antibodies (Ellinger et al., 1999; Poulsen et al., 2009). However, despite being a consolidated method, the BeWo Transwell preparation has a wide variation of parameters. Additionally, up to this date, evaluation of preferential transfer of IgG considering its subclasses and specificities have not been reported in the BeWo Transwell, limiting the ability to assess the reliability of this model for antibody translocation studies. Therefore, the focus of this project is to investigate the effect of IgG subclasses and specificity in the placental transferring of 16 CMV antibodies designed in-house by using the BeWo Transwell model in order to contribute to in-vitro studies about maternal immunization. However, the success of this study relies on first optimizing the Transwell model towards a more time-efficient preparation to reach monolayer confluency by investigating three variables: membrane coating, cell seeding density, and incubation time. Results indicate that the final ideal parameters for the Transwell setup are collagen-coat over the microporous membrane, seeding cell density of 6 ×  cells/ (200,000 cells/well for the 24-well plate), and incubation time of 72 hrs (3 days). Comparison of the preferential transfer of IgG across this BeWo Transwell model revealed that IgG4 1G2 has the best transferring performance. In the context of IgG subclasses, IgG3 has the worst relative transferring, regardless of its specificity. On the other hand, IgG4 and IgG2 show the best relative transferring performance overall. Analysis of the data by mAb specificities reveals that IgG 1G2 has the best transferring performance across the cell layer, regardless of its subclass. Future directions include quantifying the IgG transferring across the cell layer for a statistical analysis, and investigations about how mAb specificity influences IgG subclass transport across the BeWo cell layer, and how the transferring is compared to those found in-vivo.

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