Drug Antigenicity, Immunogenicity, and Costimulatory Signaling: Evidence for Formation of a Functional Antigen through Immune Cell Metabolism

Abstract

Recognition of drugs by immune cells is usually explained by the hapten model, which states that endogenous metabolites bind irreversibly to protein to stimulate immune cells. Synthetic metabolites interact directly with protein generating antigenic determinants for T-cells; however, experimental evidence relating intracellular metabolism in immune cells and the generation of physiologically relevant antigens to functional immune responses is lacking. The aim of this study was to develop an integrated approach using both animal and human experimental systems to characterize sulfamethoxazole (SMX) metabolism-derived antigenic protein adduct formation in immune cells and define the relationship between adduct formation, cell death, co-stimulatory signalling and stimulation of a T-cell response. Formation of SMX-derived adducts in antigen presenting cells was dose- and time-dependent, detectable at non-toxic concentrations and dependent on drug metabolizing enzyme activity. Adduct formation above a threshold induced necrotic cell death, dendritic cell co-stimulatory molecule expression and cytokine secretion. Antigen presenting cells cultured with SMX for 16h, the time needed for drug metabolism, stimulated T-cells from sensitized mice and lymphocytes and T-cell clones from allergic patients. Enzyme inhibition decreased SMX-derived protein adduct formation and the T-cell response. Dendritic cells cultured with SMX and adoptively transferred to recipient mice initiated an immune response; however, T-cells were stimulated with adducts derived from SMX metabolism in antigen presenting cells, not the parent drug. This study shows that antigen presenting cells metabolize SMX; subsequent protein binding generates a functional T-cell antigen. Adduct formation above a threshold stimulates cell death, which provides a maturation signal for dendritic cells.

Idiosyncratic Adverse Drug Reactions: Current Concepts

“…Exposure of keratinocytes to SMX promoted the release of proinflammatory cytokines and increased expression of heat shock protein 70 (Khan et al, 2007). We have shown that (1) SMX metabolism and protein adduct formation above a threshold stimulates cell death and (2) drugmetabolite modified necrotic cells provide a powerful activation signal to dendritic cells (Naisbitt et al, 2002;Elsheikh et al, 2010). Thus, metabolism of SMX might indirectly activate cutaneous dendritic cells and support the presentation of skin-derived drug-protein adducts.…”

“…However, oxidation of SMX hydroxylamine occurs spontaneously, generating nitroso SMX, which has been shown to modify selective cysteine residues expressed on both cellular and extracellular protein (Naisbitt et al, 1999(Naisbitt et al, , 2002Manchanda et al, 2002;Summan and Cribb, 2002;Callan et al, 2009;Eyanagi et al, 2012 ). Modification of cell surface proteins on immune cells occurs rapidly; protein conjugates are then internalized via caveolae-dependent endocytosis (Manchanda et al, 2002;Elsheikh et al, 2010).…”

“…Using a multidisciplinary approach with samples from animal and human experimental systems, we have also been able to characterize SMX metabolismderived protein adducts in immune cells and define the relationship between adduct formation, costimulatory signaling, and stimulation of a T-cell response (Sanderson et al, 2007;Lavergne et al, 2009Lavergne et al, , 2010Elsheikh et al, 2010Elsheikh et al, , 2011. The presence of various pathologic factors [e.g., lipopolysaccharide (LPS), viral proteins, and cytokines] increased the formation of protein adducts in SMX-treated dendritic cells and reduced the time needed to detect adducts.…”

Mass Spectrometric Characterization of Circulating and Functional Antigens Derived from Piperacillin in Patients with Cystic Fibrosis

“…It is thought that drugs activate T cells by covalent modification of protein generating novel antigenic determinants (2,3,(7)(8)(9). However, the paucity of studies that define the chemistry of drug-protein binding in patients has severely restricted mechanistic studies that relate the chemistry of Ag formation to immune function.…”

Cytoplasmic Distribution of HIV-1 Tat Sensitizes Jurkat T cells to Sulphamethoxazole-Hydroxylamine Induced Toxicity

“…The liver is quantitatively the primary site of SMX bioactivation, though metabolism has been shown to occur in other organs including the skin, kidney, lung and cells of the immune system [49,50]. Furthermore, SMX metabolism by dendritic cells enhances their state of activation [51,52]. We have previously shown that SMX-HA leads to the haptenation of cellular proteins [53] including HIV-1 infected Jurkat T cells and Jurkat T cells expressing the different deletion forms of Tat (data not shown).…”