1. Delayed type drug
hypersensitivity
Boonthorn
2 August 2010

2. Outline
 Pathomechanism
 Classification
 Clinical feature
◦ MP rash
◦ DRESS/DiHS, SJS/TEN, AGEP
 Allergologic workup
◦ In vivo test
◦ In vitro test

3. How drugs are recognized by the
immune system?
Pathomechanism

4. Hapten and prohapten concepts and noncovalent drug
presentation to T cells
Med Clin N Am 94 (2010) 645–664

5. Acylation of lysine residues in serum or cell surface proteins results in penicilloyl or major
antigenic determinant. From its isomer penicillanic acid, other covalent linkages to
macromolecules can occur to produce a variety of less common and/or less dominant ‘minor’
epitopes.
Middleton’s allergy. Seventh edition.

6. Sulfonamide metabolism and haptenation. Sulfonamides are metabolized by N4-oxidation by
cytochrome P450 enzymes or by N4-acetylation. N-acetyl sulfonamides and glutathionyl
(GSH) sulfonamides are then excreted. Free sulfonamides, N-acetyl sulfonamides, and GSH
sulfonamides have the potential to act as univalent inhibitors of antibody-mediated reactions.
Carrier haptenation can occur after N-oxidation if the capacity for GSH conjugation is
exceeded
Middleton’s allergy. Seventh edition.

7. The p–i concept of T lymphocyte activation. The drug happens to fit into some TCR (1) with sufficient affinity
to cause a signal. This drug-TCR interaction is supplemented by MHC interaction (2). The T cells react and
proliferate. No metabolism of drugs required. The reactive T cell is probably preactivated and has an
additional peptide specificity.
Middleton’s allergy. Seventh edition.

8.  Evidence for p-i mechanism :
◦ Aldehyde-fixed APC are still able to activate specific TCC if
incubated together with drug
◦ drug binding to proteins more labile than covalent interactions
of haptens and can be washed away
◦ Calcium influx in TCC happens within seconds ; before drug
uptake, metabolism, and processing can occur
 clinical features of p-i concept are as
follows:
◦ Positive skin test reactions to inert drugs, although no
cutaneous metabolism of this peculiar drug is known
◦ Immune reactivity at first encounter, without time of sensitization
◦ Higher risk in viral infections, to lower threshold for T cell
reactivity
◦ Fulminant course (as with superantigen stimulations)
◦ reflects abnormal T-cell stimulation with massive/fatal self-
destruction as seen in SJS/TEN and DRESS/DiHS
Med Clin N Am 94 (2010) 645–664

9. ALTEX 24, Special Issue 2007

10. Classification

11. Classifying drug
hypersensitivity
Med Clin N Am 94 (2010) 665–679

12. Characteristic chronology of drug-induced eruptions.
separation at 1 hour into immediate or nonimmediate reactions not
sufficiently reflect large overlap between pathophysiologically
determined immediate- and delayed-type clinical manifestations
Med Clin N Am 94 (2010) 711–725

13. Revised Gell and Coombs classification of drug
reactions
Med Clin N Am 94 (2010) 645–664

14. T cell orchestrated hypersensitivity reactions
(Gell and Coomb's types IVa–d)
Middleton’s allergy. Seventh edition.

15. Clinical feature

16. Maculopapular or morbilliform exanthema
 most common
 initially with erythematous
macules and infiltrated papules,
affecting particularly trunk and
proximal ext.
 (Classic) appear after 7 to 10
days
 DDx : classic infectious
exanthems eg. measles and
rubella
 In more severe reactions,
elevated eosinophil counts (~ 50%
of pts.)
 Common elicitors : ATB
(aminopenicillins and quinolones),
antiepileptic drugs, RCM
 First signs eg. discrete erythema
may even appear after a few
Med Clin N Am 94 (2010) 665–679
hours

17. Systemic danger signs for severe delayed-type
reactions
 Fever
 Malaise
 Prolonged clinical symptoms after
discontinuation of the causative drug
 Lymphadenopathy
 Eosinophilia >1.5* 109 cells /liter
 Liver involvement
Med Clin N Am 94 (2010) 665–679

18. Cutaneous danger signs for
severe delayed-type reactions

19. Central facial erythematous swelling in
DRESS syndrome (left), SJS (middle), and
TEN (right) (diffuse erythematous swelling)
Med Clin N Am 94 (2010) 681–689

20. Atypical target lesions( SJS/TEN )
Typical target lesions
 < 3 cm in diameter with a  only 2 zones, are mostly
regular round shape, flat, and irregular shape
 well-defined border, and  darker color and
2 concentric rings around sometimes central
a central disk blister
Med Clin N Am 94 (2010) 681–689

21. Positive Nikolsky sign in edematous,
erythematous skin indicating necrolytic
detachment of epidermis in SJS/TEN
Med Clin N Am 94 (2010) 681–689

22. Severe mucositis in a patient with TEN,
manifesting >1 day before epidermolysis of
skin was detectable
Med Clin N Am 94 (2010) 681–689

23. Cutaneous danger signs for severe delayed-
type reactions
 Involvement of large body surfaces or
erythroderma
 Painful skin, skin tender to touch
 Hemorrhagic necrotizing lesions
 Purpura
Med Clin N Am 94 (2010) 681–689

24. Clinical symptoms and laboratory
findings of DIHS/DRESS
Med Clin N Am 94 (2010) 743–759

25. Face swelling in early manifestation of
DRESS syndrome
 occurs in 1 in 1,000 -
10,000 exposures to
antiepileptic drugs
 2 -12 weeks after
initiation of specific
drug therapy
 Mortality ~ 10%
 anticonvulsants,
dapsone, allopurinol,
and minocycline
 DDx : viral infection
( EBV, CMV ),
autoimmune
Med Clin N Am 94 (2010) 691–710

26. Diagnostic criteria for DRESS
 MP rash developing > 3 weeks after starting with
drugs
 Prolonged clinical symptoms after discontinuation of
causative drug
 Leukocyte abnormalities (at least 1 present):
◦ Leukocytosis (>11 * 109 cells / liter)
◦ Atypical lymphocytosis (>5%)
◦ Eosinophilia (>1.5 * 109 cells / liter)
 Lymphadenopathy
 Fever (>38ºC)
 Liver abn. (ALT >100 U/L) or other organ
involvement
 HHV 6 reactivation (during 2nd to 3rd week after start
Med Clin N Am 94 (2010) 665–679
of symptoms)

27. Time interval between onset and visceral
involvements during course of DIHS/DRESS
Med Clin N Am 94 (2010) 743–759

28. Visceral organ involvements in acute stage
 Hepatitis
◦ most common (~70%)
◦ If icteric, poorer prognosis
◦ Coagulopathy in severe case
◦ Steroid benefit in fulminant hepatitis
◦ In Europe, 1 mg/kg/d of prednisolone recommended, if ALT >500 IU, Tapering
according to clinical course, too early CS reduction tends to transient
exacerbations
◦ NAC ( case report, 24g/d over 3 d )
 Nephritis
◦ ~11%
◦ kidney biopsy : AIN with lymphocytic infiltrate and ATN ( case SSZ )
 Hemophagocytic syndrome (HPS)
◦ Rare
◦ triggered by viral infection, malignant tumors, or autoimmune diseases
 Myocarditis
◦ Rare
Med Clin N Am 94 (2010) 743–759

29. Autoimmune diseases after
clinical resolution of
DIHS/DRESS
Med Clin N Am 94 (2010) 743–759

30. TOXIC EPIDERMAL NECROLYSIS
typical purulent blepharitis
Med Clin N Am 94 (2010) 727–742

31. SJS and TEN
 incidence of TEN 1.89 cases per million
per year
 Genetic susceptibility
◦ HLA-B*1502, SJS, carbamazepine in Han
Chinese ( OR =2504 ), not in Europe
◦ HLA-B*5801, SJS and TEN , allopurinol
(OR= 80) independent of ethnic background
 differential diagnoses
◦ EM major
◦ Autoimmune bullous disorder: Linear IgA
bullous dermatosis, BP, paraneoplastic
pemphigus
◦ SSSS
Am J Clin Dermatol 2003.

32. Clinical features that distinguish
SJS, SJS-TEN overlap, and TEN
Med Clin N Am 94 (2010) 727–742

33. Drugs with high risk of inducing SJS/TEN
 Antibiotics
◦ TMP/SMX
◦ Aminopenicillin
◦ Cephalosporin
◦ Quinolone
 Anticonvulsant
◦ Carbamazepine
◦ Phenytoin
◦ Phenobarbital
 Nevirapine
 Oxicam-NSAID
 Allopurinol(most common in Europe and Israel
) Med Clin N Am 94 (2010) 727–742

34. Management and Therapy
 Prompt withdrawal of culprit drugs and
supportive care
 Drug therapy , specific therapy does not
exist
 High-dose IVIg
◦ 8 /11 studies may be benefit of IVIG used (>2
g/kg over 3 to 4 days ) on mortality ( TEN )
 CsA : insufficient to draw conclusions
 Systemic steroid : remains controversial
 prevention of ocular complications
Med Clin N Am 94 (2010) 727–742

35. SCORTEN severity-of-illness score
SCORTEN Parameter Individual SCORTEN (Sum Predicted
Score of Individual Mortality
Scores) (%)
Age>40 years Yes = 1, No = 0 0–1 3.2
malignancy Yes = 1, No = 0 2 12.1
Tachycardia (>120/min) Yes = 1, No = 0 3 35.8
Initial surface of Yes = 1, No = 0 4 58.3
Epidermal detachment >10%
Serum urea >10 mmol/L Yes = 1, No = 0 5 90
( 28 mg/dl )
Serum glucose >14 mmol/L Yes = 1, No = 0
(252 mg/dl )
Bicarbonate <20 mmol/L Yes = 1, No = 0
Med Clin N Am 94 (2010) 727–742
Average mortality : SJS 1- 5%, and TEN 25- 35%

36. Acute generalized exanthematous
pustulosis
 5 cases per million
annually
 females > males
 mean age 56 years
 Treatment
◦ Exclude infectious dis.
◦ intermediate to high
doses of systemic
corticosteroids over
several days
◦ local corticosteroids of
high potency applied
for 5 - 10 days
Med Clin N Am 94 (2010) 727–742

37. Differential diagnoses of
AGEP
 Generalized pustular psoriasis
 Subcorneal pustulosis
 Subcorneal IgA dermatosis
 Infectious folliculitis
 Viral exanthema with secondary
pustulation
 Sweet syndrome(neutrophilic dermatosis )
Med Clin N Am 94 (2010) 727–742

38. Drugs with high risk for induction of
AGEP
 Ampicillin/amoxicillin
 Pristinamycin
 Quinolone
 Anti-infective sulfonamides
 Terbinafine
 Hydroxychloroquine
 Diltiazem
Med Clin N Am 94 (2010) 727–742

39. Clinical feature
SJS/TEN AGEP HSS/DRESS
Onset of reaction after taking 1–3 weeks A few days 2–6 weeks
medication
Typical duration of reaction 1–3 weeks 1 week Several weeks
Fever +++ +++ +++
Facial edema - ++ +++
Pustules - +++ +
Blisters +++ +* +*
Target lesions +++ +/- +/-
Mucosal involvement +++ +/- +/-
Histological changes in the skin Epidermal necrcrosis Subcorneal pustule Lymphocyte infiltrate
Lymph node enlargement - + +++
Lymph node histology - - Lymphoid hyperplasia
hepatitis ++ ++ +++
Other organ involvement ++*** + +++**
neutrophils ( )
eosinophils -
Atypical lymphocytes - - +
* Tension blister; ** interstitial pneumonia, interstitial nephritis; *** tracheobrochial necrosis, tubular nephritis

40. Clinical feature
SJS/TEN AGEP HSS/DRESS
Mortality SJS 1-5% <5% 10%
TEN 25-35%
Drug Nevirapine Aminopenicillins Carbamazepine
Allopurinol Cephalosporins Phenytoin
Phenytoin Pristinamycin Lamotrigine
Carbamazepine Quinolone Minocycline
Lamotrigine Macrolides Allopurinol
Co-trimoxazole Terbinafine Dapsone
Barbiturate Celecoxib Sulfasalazine
NSAIDs (oxicams) Diltiazem Co-trimoxazole

41. Allergologic Work Up

42. Tests for detection of drug-specific T cells in
patients with delayed-type drug
hypersensitivity
Immunol Allergy Clin N Am 29 (2009) 537–554

43. Guidelines in drug skin testing
 performed 6 weeks to 6 months after
complete healing of CADR
 at least 1 month after discontinuation
of systemic corticosteroid or
immunosuppressive therapy
 not to test during pregnancy
Contact Dermatitis, 2001, 45, 321–328

44. Drug Patch Testing
 performed on upper back using Finn Chambers
 read at 20 min, D2 and D4 ,D7 (if negative on D4)
 In FDE, should be performed both on normal skin
and on residual pigmented site of FDE
 with commercialized drug
◦ Incorporated at 30% in pet. and aq.
◦ made for only 1 patient and kept no > 1 D
 with pure substances
◦ diluted at 10% in pet.& aq. or alcohol (alc.).
 aciclovir, carbamazepine or pseudoephedrine
◦ first diluted at 0.1% and 1,10% ( in severe CADR)
Contact Dermatitis, 2001, 45, 321–328

45. Drug Patch Testing
 value in generalized eczema, systemic
contact dermatitis, baboon syndrome, MP
rash , AGEP , lichenoid rash and fixed
drug eruption
 less value in SJS, TEN, pruritus or
vasculitis
 most frequent reports of positive patch
tests
◦ Betalactam esp. amoxicillin, Cotrimoxazole
◦ corticosteroids , heparin derivatives ,2001, 45, 321–328
Contact Dermatitis,

46. Reading of Patch test (ICDRG) criteria

47. Drug Patch Testing
 Negative results :
◦ drug metabolite not formed in skin
◦ no immune mechanism
◦ No concomitant factors eg. Viral infection
 Best vehicle not yet been determined
◦ steroid hormone (in alcohol)
◦ Corticosteroid ( in water& alcohol)
◦ Ganciclovir ( in water )
 Positive results vary (10-60%)
Contact Dermatitis, 2001, 45, 321–328

48. Intradermal Tests (IDT)
 Contraindicated in SJS, TEN or LCV
 diluted sequentially (10-4, 10-3, 10-2 and 10-1) in
phenolated saline or in 0.9% saline
 performed on extensor surface of arm, with
small volume (0.04 ml) produces weal (4-6
mm)
 Readings performed at 30 min, 6 h and 1 D (
1 week, if result are negative )
 risk of eliciting relapse of initial CADR ( 3
minor incidents/30)
Contact Dermatitis, 2001, 45, 321–328

49. Intradermal test results positive for Patch test results positive for AX
AX and AM and AM
Nonimmediate skin test results
Med Clin N Am 94 (2010) 805–820

50. Drugs Patch test Intradermal test
Aminopenicillins 10% in Pet. 20-25 mg/ml
Cephalosporins 10% in Pet. 1/10 of full strength
Pristinamycin 10% in Pet.
Quinolone 30% in Pet. Or water 1/100 of full strength
Co-trimoxazole 10% in Pet. 1/100 of full strength
Minocycline 10% in Pet.
Carbamazepine 1%,10% in Pet.
NSAIDs (oxicams) 1%,10% in Pet.

51. Lymphocyte Transformation
Test
 most widely used test
 principle : simple proliferation test with Ag
 useful in MPE, pustular exanthema, bullous
exanthema and DRESS
 cultured in presence of suspected drug for 6
days
 measured by incorporation of 3H-thymidine
during DNA synthesis
 stimulation index (SI) >2 ( 3 for betalactam )
 not necessarily associated with clinical
severity
 Sensitivity 60- 70% (depends on drug tested,
Immunol Allergy Clin N Am 29 (2009) 537–554
> skin test )

52. Lymphocyte Transformation
Test
 Specificity ~ 85%
 Perform in 1-6 mo. After event ( bullous
dis., positive in first week of dis.)
 False positive :vancomycin, possibly
paracetamol, and RCM
 False negative :abacavir
 disadvantages:
◦ requires sterile cell cultures
◦ takes a long time and cumbersome
◦ depends on quality of culture medium
◦ involves radioactivity, and expensive
equipment
Immunol Allergy Clin N Am 29 (2009) 537–554

53. CD69 UP-REGULATION
 CD69 : membrane type II C-type lectin,
transiently expressed on activated
lymphocytes
 up-regulated in T cells from patients who
had drug-induced MPE, erythema
multiforme, SJS, and DRESS when
assessed by flow cytometry
 comparable to LTT
 Advantage : not require radioactive
substances and less time-consuming
 Disadvantage : flow cytometry-based
test, difficult to standardize
Immunol Allergy Clin N Am 29 (2009) 537–554

54. Immunol Allergy Clin N Am 29 (2009) 537–554

55. Measurement Of Drug-induced Cytokine
Production From Ex Vivo PBMC
 measurement of IL-2, IL-5, IL-13, and IFN-γ
cytokines might be promising tool for detecting
drug sensitization in delayed-type reactions
 ELISA or ELISPOT assay, or multiplexed bead-
based flow cytometric assays, mRNA by RT-
PCR
 IFN-γ ELISPOT assay exhibited high sensitivity
and specificity since specific T cells were
detected in 20/22 ( 91%) of amox-DTH patients
 only 1/26 nonDTH allergic patient had
unexpected but weak reactivity to unrelated
control antibiotic
Immunol Allergy Clin N Am 29 (2009) 537–554
Allergy 2009: 64: 534–542

56. ELISA ELISPOT
Immunol Allergy Clin N Am 29 (2009) 537–554

57. Cytotoxicity: Granzyme B Enzyme
Immunospot Assay
 gives results 48 to 72 hours after stimulation
and not involve radioactivity
 Once cytotoxic T cells get activated, lytic
granules reach plasma membrane,
granzymes and perforin released into
immunologic synapses, and cumulative
exposure of granular membrane proteins
(CD107a) can be measured on surface of
responding cytotoxic cells, providing positive
marker for degranulation
 seems to be most sensitive and robust
method to detect cytotoxic cells in peripheral
blood of drug-allergic patients
Immunol Allergy Clin N Am 29 (2009) 537–554

58. Cytotoxicity: Granzyme B Enzyme
Immunospot Assay
Immunol Allergy Clin N Am 29 (2009) 537–554

59. When Should Diagnostic Tests Be
Performed?
 recommend performing LTT within 1 week
after onset of skin rashes in MP eruptions
and SJS or TEN and > 5 to 8 weeks after
event in DRESS
 some patients lose reactivity within 1 to 3
years after reaction
 many groups carry out tests after of 3 weeks-
6 months after acute event
 In vitro tests offer advantage of safety,
simultaneous assessment of T-cell responses
to multiple drugs, lack of risk for
resensitization, and insight into
pathomechanism
Immunol Allergy Clin N Am 29 (2009) 537–554

60. Conclusion
 Delayed type drug hypersensitivity
classified by pathomechanism (type IVa-
d)
 MP rash : most common
 SJS/TEN : most severe, treatment is
supportive care ( may be try IVIg )
 Skin test ( patch test, ID test ): low
sensitivity
 In vitro test : LTT ( gold standard ), other
test remained study

61. conclusion
SJS/TEN AGEP HSS/DRESS
Onset of reaction after taking 1–3 weeks A few days 2–6 weeks
medication
Typical duration of reaction 1–3 weeks 1 week Several weeks
Fever +++ +++ +++
Facial edema - ++ +++
Pustules - +++ +
Blisters +++ +* +*
Target lesions +++ +/- +/-
Mucosal involvement +++ +/- +/-
Histological changes in the skin Epidermal necrcrosis Subcorneal pustule Lymphocyte infiltrate
Lymph node enlargement - + +++
Lymph node histology - - Lymphoid hyperplasia
hepatitis ++ ++ +++
Other organ involvement ++*** + +++**
neutrophils ( )
eosinophils -
Atypical lymphocytes - - +
* Tension blister; ** interstitial pneumonia, interstitial nephritis; *** tracheobrochial necrosis, tubular nephritis

62. Conclusion
SJS/TEN AGEP HSS/DRESS
Mortality SJS 1-5% <5% 10%
TEN 25-35%
Drug Nevirapine Aminopenicillins Carbamazepine
Allopurinol Cephalosporins Phenytoin
Phenytoin Pristinamycin Lamotrigine
Carbamazepine Quinolone Minocycline
Lamotrigine Macrolides Allopurinol
Co-trimoxazole Terbinafine Dapsone
Barbiturate Celecoxib Sulfasalazine
NSAIDs (oxicams) Diltiazem Co-trimoxazole