The mechanisms of absence of immune response may vary and involve complex immunological interactions, but can include absent or insufficient co-stimulatory signals from antigen-presenting cells.
Haptens have been used to study allergic contact dermatitis (ACD) and the mechanisms of inflammatory bowel disease (IBD) to induce autoimmune-like responses.
The second elicitation phase where the hapten is applied to a different skin area starts with activation of effector T cells followed by T cell-mediated tissue damage and antibody-mediated immune responses.
Haptens initially activate innate immune responses by complex mechanisms involving inflammatory cytokines, damage-associated molecular patterns (DAMP), or the inflammasome.
After a second exposure, the proliferated T-cells become activated, generating an immune reaction that produces typical blisters of a urushiol-induced contact dermatitis.
Antibodies have successfully been raised against endogenous & unreactive small molecules such as some neurotransmitters (e.g. serotonin (5HT), glutamate, dopamine, GABA, tryptamine, glycine, noradrenaline), amino acids (e.g. tryptophan, 5-hydroxytryptophan, 5-methoxytryptophan), by using glutaraldehyde to crosslink these molecules to carrier proteins suitable for immune recognition.
[14] In general, carrier proteins should be immunogenic and contain enough amino acid residues in the reactive side chains to conjugate with the haptens.
Depending on the haptens being used, other factors in considering the carrier proteins could include their in vivo toxicity, commercial availability and cost.
[21] In allergology, in vitro/in silico tests for skin sensitization, hazard identification, and potency evaluation on different drug and cosmetic components are highly preferred in early product development.
[22] Hapten-specific antibodies are used in broad area of different immunoassays, immunobiosensor technologies and immunoaffinity chromatography purification columns; those antibodies could be used to detect small environmental contaminants, drugs of abuse, vitamins, hormones, metabolites, food toxins and environmental pollutants.