Immunotoxicology: Immune Responses, Hypersensitivity & Assays

Immunotoxicology

Study of adverse effects of toxicant exposures on the immune system.

Primary Lymphoid Organs

Bone marrow (producing B cells and stem cells) and thymus (producing T cells).

Secondary Lymphoid Organs

Spleen and lymph nodes that act as biological sieves to bring naive lymphocytes into contact with exogenous antigens.

Innate Immunity

Nonspecific first line of defense with physical barriers and no immunological memory.

Adaptive Immunity

Specific defense mechanism characterized by pathogen specificity and immunological memory.

Haptens

Small antigens that must conjugate with carrier molecules to become immunogenic and elicit a response.

Neutrophils

Polymorphonuclear phagocytic cells acting as the first line of defense by releasing reactive oxygen species.

Dendritic Cells

Professional antigen-presenting cells (APCs) acting as a bridge between innate detection and adaptive response.

Toll-like Receptors (TLRs)

Receptors on macrophages and dendritic cells that recognize pathogen-associated molecular patterns (PAMPs).

Humoral Immune Response

Immune response involving B cells that produce antigen-specific antibodies to neutralize or opsonize invaders.

Cell-Mediated Immune Response

Immune response mediated by CD8+ Cytotoxic T-lymphocytes that destroy antigen-infected cells.

Type I Hypersensitivity

Immediate, IgE-mediated allergic response causing mast cell degranulation and histamine release.

Type IV Hypersensitivity

Cell-mediated hypersensitivity involving T cells rather than antibodies, such as poison ivy contact dermatitis.

Autoimmunity

Inappropriate immune response directed against the body's own normal tissues and cellular components.

TCDD (Dioxin)

Potent environmental contaminant binding to the aryl hydrocarbon receptor (AHR), causing T-cell and B-cell impairment.

Local Lymph Node Assay (LLNA)

OECD assay measuring 3H-thymidine incorporation to assess skin sensitization and auricular lymph node infiltration.

Plaque Forming Cell (PFC) Assay

Assay measuring the ability of host B cells to mount an antibody response against sheep red blood cells.

Nickel Toxicity

Common occupational and jewelry-related exposure leading to allergic contact dermatitis.

Biologics

Therapies derived from living organisms (like monoclonal antibodies) that carry potential risks of immunogenicity.