Autoimmune blistering is cell adhesion losing its jam. Putting the already-measured KRT14 γ on the same R19 switch makes junctional adhesion a hysteretic two-state bond — adherent when jammed ON, blistered when an autoantibody drives it OFF. Pemphigus vulgaris and bullous pemphigoid then differ only by which compartment the antibody hits, flipping the cleavage plane, the Nikolsky sign and the blister tension with no fitted constant.
Junctional cell adhesion — the desmosomal and hemidesmosomal bonds that hold the epidermis together — is reproduced as a hysteretic two-state binding jam on the same R19 switch as the barrier and wound, running on the already-measured keratinocyte KRT14 γ with no new γ fetched and none fitted. The bond detaches discontinuously at a lower spinodal and re-adheres only at a higher one [V] Simulation-verified; the adhesion reserve and antibody titres are forced regime scales [F] Forced (substrate), the clinical mappings are cited anchors [L] Cited anchor, and absolute blister counts and titres stay open [O] Open (obstacle stated). Pemphigus vulgaris (anti-DSG3, the cell-cell compartment) and bullous pemphigoid (anti-BP180, the cell-matrix compartment) follow as the same switch hit by the same antibody magnitude in different compartments, passing an intervention-reversal battery and a three-axis opposite-property discriminant — intraepidermal vs subepidermal plane, positive vs negative Nikolsky sign, flaccid vs tense blister — the layer adding no constant while the core-battery hash stays fixed.
Cell adhesion is a binding jam — the same physical class, on an organ already in the atlas
Desmosomes and hemidesmosomes anchor the keratinocyte's keratin network to its neighbours and to the basement membrane; that junctional adhesion is what holds the epidermis together as a sheet. In this framework adhesion is not a new organ — it is an intrinsic property of the keratinocyte, so it runs on the already-measured KRT14 γ with no new γ fetched and none fitted (the hair-cycle pattern of a new target on an existing organ, not the sebaceous pattern of a new measured organ). A bond is a member of the package's jamming class read the natural way round: adherent = jammed ON (s>0), blistered = unjammed OFF (s<0). An autoantibody is a de-adhesive drive, and which compartment it targets is the only thing that changes between the two classic autoimmune blistering diseases.
| Quantity | Value | Meaning |
|---|---|---|
| Master gene (reused, measured) | KRT14 γ = 1.4894 | the keratinocyte γ already vendored for the barrier and turnover pages — adhesion is intrinsic to this organ |
| New γ fetched | no | no NCBI fetch and no fit — only a new dynamical target on the existing measured γ |
| Spinodal | 0.6996 | substrate-derived from the same γ (sets the de-adhesion regime scale) |
| Healthy net adhesion | 1.40 | the healthy bond sits ABOVE the upper spinodal, robustly adherent (yes) |
Acquired autoimmune blistering is keyed by dynamics — a de-adhesive drive on an intact bond — and is reproduced here. Its congenital mirror, epidermolysis bullosa, is keyed by a defective adhesion gene (KRT14, COL17A1, LAMB3) and belongs to the gene-lesion disease registry, not to this dynamical layer; naming that boundary keeps each disease where its mechanism actually lives.
Adhesion is a hysteretic two-state bond, not a graded weakening
Run as the R19 switch, the bond does not soften smoothly as the de-adhesive drive rises. It stays firmly adherent, then detaches discontinuously at the lower spinodal (a jump of about 2.11 at net adhesion ≈ -1.005); restoring adhesion does not re-anneal at the same level but only at a higher spinodal (net adhesion ≈ 1.005), tracing a hysteresis loop of width about 2.01. Discontinuous detachment (yes) and a finite loop (yes) are the first-order signature — the simulation-verified core [V] Simulation-verified of this page, taken straight from the substrate with nothing tuned. The clinical reading is immediate: a blister, once raised, does not reseal the moment the antibody titre eases a little; the bond has to be carried back above a distinctly higher threshold, which is why a partial reduction in titre leaves disease active and only substantial clearance re-adheres.
The page is explicit about what it does not claim. The hysteresis shape — discontinuity, the loop, the adherent set-point, and the plane/sign selection below — is verified [V] Simulation-verified; the adhesion reserve and the antibody titres are dimensionless regime scales [F] Forced (substrate); the clinical mappings are cited anchors [L] Cited anchor. The absolute blister counts, the antibody titre in IU/mL, the cleavage depth in microns and the involved body-surface area remain open [O] Open (obstacle stated), inheriting the adhesion target's obstacle — a per-junction calibration. The bond is graded on direction, discontinuity, hysteresis, plane and sign, never on a fitted magnitude.
Two blistering diseases are one switch hit in two compartments
Adhesion runs in two coupled compartments on the same γ and the same spinodal: cell-cell (desmosomal, DSG3) and cell-matrix (hemidesmosomal, BP180/COL17A1). An autoantibody of the same magnitude detaches whichever compartment it is specific for — and that single choice is the entire difference between the two diseases.
| Disease | Autoantibody & compartment | Covered as |
|---|---|---|
| Pemphigus vulgaris | anti-desmoglein-3 (DSG3) — the cell-cell (desmosomal) compartment | drives lateral cohesion below the spinodal → an intraepidermal (suprabasal) split with the cell-matrix bond intact (basal 'tombstone' row); clearing the antibody re-adheres it |
| Bullous pemphigoid | anti-BP180 (COL17A1) — the cell-matrix (hemidesmosomal) compartment | drives basal anchoring below the spinodal → a subepidermal split with the cell-cell bonds intact (epidermis lifts whole); clearing the antibody re-adheres it |
Pemphigus vulgaris: the cell-cell bond detaches, splitting within the epidermis
An anti-DSG3 autoantibody drives the cell-cell (desmosomal) compartment below the spinodal, so keratinocytes lose lateral cohesion (yes) while the untouched cell-matrix bond keeps basal cells anchored (yes). The split is therefore intraepidermal suprabasal — suprabasal, leaving the basal 'tombstone' row — and because the failing bond is the lateral cell-cell bond, a tangential shear propagates the separation, so the Nikolsky sign is positive (yes); the thin suprabasal roof gives a flaccid blister (yes). The Nikolsky sign is derived from which compartment failed, not asserted. Reversal follows the hysteresis exactly: a partial titre reduction does not re-adhere (no), but clearing the antibody (rituximab / immunosuppression) carries net adhesion back above the spinodal and the bond re-adheres (yes).
Bullous pemphigoid: the cell-matrix bond detaches, lifting the epidermis whole
An anti-BP180 (COL17A1) autoantibody of the same magnitude instead drives the cell-matrix (hemidesmosomal) compartment below the spinodal, so basal keratinocytes detach from the dermo-epidermal junction (yes) while the untouched cell-cell bonds hold the epidermis together as a cohesive sheet (yes). The split is now subepidermal junctional — the whole epidermis lifts as an intact roof — and because the failing bond is the basal cell-matrix bond and not the lateral one, a tangential shear does not propagate, so the Nikolsky sign is negative (yes); the full-thickness roof gives a tense blister (yes). Reversal is again hysteretic: a partial reduction does not re-adhere (no), while clearing/suppressing the antibody (corticosteroid / immunosuppression) re-adheres the bond (yes).
The discriminant: opposite blistering properties from one switch, one spinodal, one antibody magnitude
The decisive evidence is the same as for the static diseases, the hair cycle and the sebaceous duct: clinically opposite behaviours fall out of the same jam — here not even driven to different depths, but driven in different compartments at the same antibody magnitude. Nothing is changed between the two diseases except which bond the antibody is specific for.
| Axis | One pole | Opposite pole | Reproduced |
|---|---|---|---|
| Cleavage plane | intraepidermal / suprabasal (pemphigus vulgaris) | subepidermal / junctional (bullous pemphigoid) | yes |
| Nikolsky sign | positive (pemphigus vulgaris) | negative (bullous pemphigoid) | yes |
| Blister tension | flaccid (pemphigus vulgaris) | tense (bullous pemphigoid) | yes |
All three opposite pairs reproduce (yes). That one adhesion switch yields an intraepidermal versus a subepidermal plane, a positive versus a negative Nikolsky sign, and a flaccid versus a tense blister — from the compartment alone, on a single reused KRT14 γ with no new parameter and the same antibody magnitude — is the strongest internal evidence that these blistering diseases are adhesion-jamming dynamics, not bespoke fits.
Grades and reproducibility
Every mechanism here is a simulation-verified shape or sign [V] Simulation-verified — discontinuous detachment, the hysteresis loop, the adherent set-point, the plane selection, the derived Nikolsky sign, the blister-tension direction and the re-adhesion on antibody clearance. Every clinical mapping rests on a cited anchor [L] Cited anchor. The adhesion reserve and antibody titres are forced regime scales [F] Forced (substrate). Every absolute magnitude is open [O] Open (obstacle stated) — blister counts, titre in IU/mL, cleavage depth, body-surface area — inheriting the adhesion target's obstacle (a per-junction calibration). No disease introduces a new constant; each is a signed de-adhesion of the one bond, and no new γ is fetched.
The adhesion pipeline is deterministic on its own terms: two independent runs hash to an identical SHA-256, separate from the core battery, the pathology layer, the hair-cycle layer and the sebaceous layer. Crucially, adding this target does not touch the core T1–T5+oncology battery, whose result hash is unchanged at 1fb59f556e01….