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Johns Hopkins Bloomberg School of Public HealthCAAT

Developmental Immunotoxicity

Fenna Sille

Coordinator: Fenna Sille (

In the summer 2019, CAAT officially launched the effort towards a framework for alternative methods for developmental immunotoxicity testing, with the formation of the International Working Group around the topic of Alternatives to in vivo Developmental Immunotoxicity Testing.


The development of non-animal New Approach Methods (NAMs) has been widely ac­knowledged as a critical need for toxicity testing (NRC, 2007). Alternative/non-animal test methods are needed for various reasons including but not limited to: ethical animal welfare considerations (reduction & replacement); evaluation of more chemicals across a broader range of potential biological effects; evaluating more chemicals in a shorter time frame with fewer resources, while striving for equal or greater level of human health protection. Although critical windows of developmental immunotoxicity (DIT) have been defined by the field, developmental toxicity at the moment is mainly done using whole animal studies. Due to the ethical limitations to clinically evaluate the effects of drugs and other exposures on the developing immune system in utero in pregnant women, sensitive in vitro assays that are translatable across species could be of great value. The development of NAMs for developmental immunotoxicity is also important especially in a regulatory context to develop an OECD guideline. Current OECD testing guideline methods for DIT depend mainly on the extended one-generation and limitations of the current methods for assessing DIT.

The Problem Addressed

Unfortunately, the current status of in vitro assays available for DIT screening is unclear. Amongst other factors, there is the need to:

  1. Identify key molecular and biological events in developmental immunology that are important to assess during DIT testing.
  2. Identify when and why in vivo and in vitro DIT testing strategies are needed in the context of chemical development programs, regulatory hazard screening, regulatory risk assessment, and potential triggers for testing requirements. This includes surveying industry and regulators to determine what is required in different regulatory programs both across different countries as well as across different chemical programs (e.g. industrial chemicals, drugs, pesticides)
  3. Identify DIT reference chemical candidates: e.g. from extended one-generation study.
  4. Identify which existing in vitro strategies are useful and appropriate in the context of when and why DIT testing strategies are needed.
  5. Identify gaps in existing in vivo and in vitro testing schemes that could be addressed by the development of novel in vitro DIT assays or testing strategies.
  6. Identify appropriate endpoints and adverse outcome pathways (AOPs) which could be used as a foundation to identify DIT hazard and potency with sufficient certainty to inform regulatory hazard or risk assessment.
  7. To evaluate the feasibility of in vitro DIT testing strategies to reduce/replace in vivo DIT strategies.

With this in mind the Center for Alternative Animal Testing has formed an international working group around the topic of “Alternatives to in vivo Developmental Immunotoxicity Testing”. The working group consists of representing stakeholders from regulatory agencies, non-governmental organizations (NGOs), academia and industry to help pave the road towards alternative methods for assessing developmental immunotoxicity testing.

This working group focuses on assessing and advancing the topic using evidence-based methodologies, to bring transparency, objectivity and consistency to the project. The goal of the working group is to identify gaps in the field of alternative DIT and to establish a framework to encourage the refinement and development of new alternative test methods suitable for screening of (large numbers of) DIT compounds. The ultimate intent is to develop a methodology for alternative DIT screening (e.g. a tiered approach) and develop test guidelines that can be incorporated in OECD guidance documents and overall testing strategy for both applied and regulatory purposes.

Working Group Steering Committee

Fenna C. M. Sillé, PhD
Assistant Professor in Environmental Health & Engineering
Center for Alternatives to Animal Testing at Johns Hopkins Bloomberg School of Public Health (CAAT)
Johns Hopkins Bloomberg School of Public Health

Helena Hogberg, PhD
Deputy Director, Center for Alternatives to Animal Testing at Johns Hopkins Bloomberg School of Public Health (CAAT)

Katya Tsaioun, PhD
Director, Evidence-based Toxicology Collaboration at Johns Hopkins Bloomberg School of Public Health (EBTC)

Current Working Group Participants


Johanna Gostner, PhD (Biocenter, Medical University of Innsbruck)

Emanuela Corsini, PhD (University of Milan)

Robert Wright (Librarian III, John Hopkins, SOM Admin Welch Informationist Services)


Dori R. Germolec, PhD (NTP/NIEHS)

Suzanne Fitzpatrick, PhD, DABT (FDA)

Cameron Bowes, PhD (Health Canada)

David Lefebvre, PhD (Health Canada)

Shifawn O'hara, PhD (Health Canada)

Industry & End-users

Leigh Ann Burns-Naas, PhD, DABT, ERT, ATS (Magnolia Toxicology Consulting, LLC)

Mark Collinge, PhD (Pfizer)

Vic Johnson, PhD (BRT Labs)

Current Activities

Expert opinion article: The first project by the working group is an expert opinion article in which the working group lays out the need (from both regulatory as well as end-user) for alternatives to animal research for developmental immunotoxicity testing. The article will also highlight the need for in depth assessment and review of other areas important towards the development of alternatives to DIT, including: epidemiologic evidence for developmental immunotoxicity; windows of susceptibility; key elements required for testing battery that can identify DIT hazard and potency for regulatory hazard and risk assessment; and the need for development of a reference set of known developmental immunotoxicants.

Scoping Review: The working group is currently working on a “Systematic scoping review of developmental immunotoxicity mechanistic endpoints and associated new approach methodologies (NAM)”. This scoping review is intended to provide the working group with a solid foundation of evidence-based toxicology for the developing immune system, and will then define more specific areas the working group can focus on. This project is supervised by the Evidence-Based Toxicology Collaboration (EBTC,

Workshop: A two-day workshop on Alternatives to in vivo DIT testing was supposed to be held at Johns Hopkins University School of Public Health in September 2020. For COVID-10 reasons this in-person workshop has been postponed until further notice. In the meantime, a 3-part series of virtual mini- expert workshops around specific topics have been planned for 2021. The first expert workshop in May 2021 is on the Identification of Key Molecular and Biological events in Developmental Immunotoxicity. The purpose of these virtual mini expert workshops is to bring together the breath of expertise in developmental immune(toxico)logy with in vitro immuno(toxico)logy to address key knowledge gaps for DIT.

We have identified experts in the field, whom will be specifically invited for these workshops. The workshops will also seek participation from the broader community. The workshops will be structured in a way that minimal time will be spent on informative seminar lectures and the majority of the time will be spent in breakout sessions to discuss the identified issues in detail. Notes from each breakout group will be compiled into a comprehensive published report per workshop. The emphasis will be placed on identifying concrete definitions, problems and action items for follow up by the field.

Calendar of Events

Current- March 2021: Expert opinion article by core working group

Current- December 2021: Scoping review by core working group

May 4-5, 2021: Virtual expert workshop #1: “Identification of Key Molecular and Biological events in Developmental Immunotoxicity”

Spring/Summer 2021: Write up from workshop #1

July/August 2021: Virtual expert workshop #2: Topic TBD

Winter 2021: Write up from workshop #2

November/December 2021: Virtual expert workshop #3: Topic TBD

Spring 2022: Write up from mini-workshop 3

Call to Action

Intellectual (workshop participation)

Resources (we are looking for SOPs, AOPs, or other documents containing alternatives to DIT)

Contact Us

Center for Alternatives to Animal Testing at Johns Hopkins Bloomberg School of Public Health (CAAT)
Alternatives to in vivo Developmental Immunotoxicity Testing Working Group
615 N Wolfe Street, W7032
Baltimore, MD 21205