Immunotoxicology is the study of the adverse effects of chemical substances on the immune system. It involves evaluating the potential of various chemicals, including drugs, environmental pollutants, pesticides, and industrial chemicals, to alter immune function and increase susceptibility to infections, autoimmune diseases, allergies, and other immune-related disorders.

Here are the key aspects and areas of focus within immunotoxicology:

1. Immune System Components: The immune system is a complex network of cells, tissues, and molecules that work together to defend the body against pathogens and maintain overall health. Immunotoxicology examines the effects of chemicals on different components of the immune system, including immune cells (such as T cells, B cells, macrophages, and dendritic cells), antibodies, cytokines, and other immune factors.
2. Immunotoxicity Testing: Immunotoxicity testing involves in vitro and in vivo studies to assess the effects of chemicals on immune function. These tests include evaluating immune cell proliferation, antibody production, cytokine secretion, phagocytosis, natural killer cell activity, and other immune responses. Animal models are commonly used to assess immunotoxicity, and specific assays are designed to measure changes in immune parameters following chemical exposure.
3. Innate and Adaptive Immunity: Immunotoxicology studies explore the effects of chemicals on both innate and adaptive immunity. Innate immunity provides the first line of defense against pathogens, while adaptive immunity involves the production of specific immune responses tailored to a particular pathogen. Chemicals can modulate the functioning of innate immune cells, such as neutrophils and natural killer cells, as well as affect the activation and function of T cells and B cells in adaptive immunity.
4. Allergic and Hypersensitivity Reactions: Immunotoxicology investigates the potential of chemicals to induce allergic and hypersensitivity reactions. These reactions involve an overactive immune response to otherwise harmless substances, leading to symptoms such as skin rashes, asthma, or anaphylaxis. Chemicals can act as allergens or sensitize the immune system to subsequent exposures, resulting in hypersensitivity reactions.
5. Autoimmunity: Autoimmune diseases occur when the immune system mistakenly attacks the body’s own cells and tissues. Immunotoxicology studies explore the potential of chemicals to trigger or exacerbate autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, or multiple sclerosis. Chemicals can disrupt immune tolerance mechanisms, promote inflammation, or induce autoimmune responses.
6. Immunotoxicity Mechanisms: Understanding the mechanisms through which chemicals induce immunotoxicity is a key aspect of immunotoxicology. Mechanistic studies investigate how chemicals affect immune cell signaling, gene expression, antigen presentation, lymphocyte activation, and immune regulation. These studies help unravel the underlying biological pathways and processes involved in immunotoxicity and provide insights into the potential risks associated with chemical exposures.
7. Regulatory Considerations: Immunotoxicity data are important in regulatory decision-making and risk assessment. Regulatory agencies, such as the US Environmental Protection Agency (EPA) and the European Chemicals Agency (ECHA), require immunotoxicity data for the registration and approval of chemicals. The results of immunotoxicology studies inform hazard classifications, exposure limits, risk management strategies, and the establishment of guidelines to protect human health and the environment.

Immunotoxicology plays a crucial role in assessing the potential risks of chemical exposures on immune function and overall health. By understanding how chemicals can alter immune responses, immunotoxicology contributes to the development of safer chemicals, helps inform risk assessment, and supports the protection of individuals from immune-related disorders.