The autoimmunogenic chemicals HgCl₂ and diphenylhydantoin stimulate IgG production to TNP–Ficoll and TNP–OVA, supporting and extending the graft‐versus‐host hypothesis for chemical induction of autoimmunity

Abstract

SUMMARYBypass of T-cell tolerance via non-cognate graft-versus-host (GVH)-like help from T-helper (Th) cells activated by chemically altered or induced epitopes, has been postulated as a mechanism underlying chemical induction of autoimmunity. To functionally test this hypothesis, we assessed whether the autoimmunogenic chemicals HgCl 2 and diphenylhydantoin (DPH), like GVH reactions, stimulate specific immunoglobulin G (IgG) responses to trinitrophenyl (TNP)-Ficoll but not to TNP-ovalbumin. IgG responses were quantified in the popliteal lymph node by enzyme-linked immunosorbent spotforming cell assay (ELISPOT) assays 7 days after s.c. injection of antigens, parental cells, chemicals or combinations thereof into the footpad of semi-allogeneic F1 mice. Antigens, chemicals, or cells alone induced few TNP-specific IgG antibody-forming cell (AFC) compared with untreated mice. Coinjection of parental cells or chemicals with TNP-Ficoll stimulated the TNP-specific response per lymph node 50-and 40-fold, respectively. In contrast, the IgG response to TNP-ovalbumin could not be stimulated by GVH reactions, whereas HgCl 2 and DPH dose-dependently increased this response up to 25-and 250-fold, respectively. However, responses to TNP-ovalbumin pre-incubated with HgCl 2 or DPH could be stimulated 6-8 fold by GVH reactions. Observed similar adjuvanticity of chemicals and parental cells for TNP-Ficoll support a GVH-like action of autoimmunogenic chemicals. In addition, the chemicals modify TNP-ovalbumin such that B cells recognizing this antigen become susceptible to noncognate stimulation by GVH reactions.

Selective Requirement for CD40-CD154 in Drug-Induced Type 1 Versus Type 2 Responses to Trinitrophenyl-Ovalbumin

“…A value of p Ͻ 0.05 was considered statistically significant. Our present observations confirm earlier results described by Albers and colleagues (25,26) showing that coinjection of TNP-OVA with DPH or D-Pen elicits type 2 responses, whereas exposure to STZ stimulates a type 1 response. Responses evoked by DPH and D-Pen are characterized by elevated levels of TNP-specific IgM, IgG1, and IgE ASC numbers (Fig.…”

“…Saline (0.9%; B. Braun Melsungen, Melsungen, Germany) and citrate buffer (0.1 M citric acid and 0.1 M disodium hydrogen phosphate, pH 6) were used to dilute test chemicals. TNP-OVA and blocking agent TNP-BSA were prepared as previously described by Albers et al (26). MR1 was used as anti-CD154 Ab, which was a gift from Tanox Pharma (Amsterdam, The Netherlands).…”

“…Previously, we have shown that the response to TNP-OVA parallels the type of response expected to occur in the case of the xenobiotic itself (25). Notably, the response to TNP-OVA in the presence of the lupus-inducing chemicals HgCl 2 and diphenylhydantoin (DPH; anti-epileptic drug) is type 2 (IgG1 Ab-secreting cells (ASC), GC formation, influx of IL-4-producing CD4 ϩ cells) (26), whereas the response to the same Ag elicited by the antineoplastic diabetogenic chemical streptozotocin (STZ) is type 1 (IgG2a ASC, influx of IFN-␥-producing CD8 ϩ cells and macrophages) (27).…”

The Reactive d-Glucopyranose Moiety of Streptozotocin Is Responsible for Activation of Macrophages and Subsequent Stimulation of CD8+ T Cells

“…Because both STZ and MNU are NO donors, SNAP was used as a nonrelated NO donor to study the adjuvant effect of NO. As reference chemicals of classical IgG1-inducing compounds, D-Pen and HgCl 2 were used (17,25). Figure 4A shows the distribution of IgG2a vs IgG1 of TNP specific ASC and indicates that SNAP, D-Pen, and HgCl 2 induced clear type 2 (IgG1) responses, whereas STZ and MNU induced type 1 antibody production (IgG2a).…”

Investigating the TNP‐OVA and direct popliteal lymph node assays for the detection of immunostimulation by drugs associated with anaphylaxis in humans

“…This method of reporting has been used previously in the TNP-OVA PLNA. 40 Second, by reporting the AFCs per PLN we eliminated any error associated with counting cells. Finally, plating 50 µl of cells from the 500-µl preparation allowed the cells to be placed on the precoated membrane and placed in the incubator immediately after isolating the cells.…”