This document summarizes different types of hypersensitivity reactions and methods used to study antiallergics. There are four types of hypersensitivity reactions: Type I is an immediate IgE-mediated allergy, Type II involves IgG and IgM antibodies binding to cell surfaces, Type III involves immune complex formation and inflammation, and Type IV is a delayed cell-mediated reaction. Two in vivo methods studied are acute systemic anaphylaxis in rats to test Type I reactions, and the Schultz-Dale reaction using guinea pigs to study anti-anaphylactic effects on Type I hypersensitivity in the ileum. Several other in vivo and in vitro tests are also described to evaluate potential antiallergic drugs

1. ANTIALLERGICS’
By
RAVILLA JYOTHSNA
M.PHARM IYear(PHARMACOLOGY)
SCREENING OF

2. HYPERSENSITIVITY
REACTIONS
• these are undesirable immune reactions produced by normal immune system.
• When an immune response results in exaggerated or in appropriate reactions
harmful to the host the term hypersensitivity or allergy is used.
• These are 4 types mainly I, II, III, IV.

3. Classification of Hypersensitivity
• Type I
• Type II
• Type III
• Type IV
Type I, II and III are Antibody mediated.
Type IV Cell mediated.

4. Hypersensitivity reactions:
TYPE MECHANISM ANTIGEN ONSET
I IgE- Ag triggers Mast cell
mediators.
Allergen minutes
II IgM or IgG binds to cell
surface; ADCC or complement.
Cell surface molecule Few hours
III Immune complexes,
inflammation
Soluble or particulate Few hours.
IV Cytokines (T cells,
macrophages, CTL)
Chemicals, intracellular 1-3 days

5. IN VITRO METHODS
• Inhibition of Histamine release from Mast cells.
• Mitogen induced Lymphocyte proliferations.
• Inhibition of T cell proliferation.
• PFC (plague forming colony) test in vivo.
• Inhibition of dihydro- orotate dehydrogenase.

6. IN VIVO methods
• Acute systemic anaphylaxis in rats.
• Anti- anaphylactic activity in guinea pigs. (Schultz- Dale reaction)
• Delayed type of hypersensitivity.
• Passive cutaneous anaphylaxis in rats.
• Arthus type immediate hypersensitivity.
• Spontaneous autoimmune diseases in animals.
• Reversed passive arthus reaction.
• Adjuvant arthritis in rats.

7. • Collagen type 2 induced arthritis in rats.
• Proteoglycan induced progressive polyarthritis in mice.
• Experimental autoimmune thyroiditis.
• Procine cardiac myosin induced autoimmune myocarditis in rats.

8. IN VIVO METHODS

9. 1.Acute systemic anaphylaxis in rats:
• Rats are sensitized by ovalbumin and Bordetella pertusis.
• After 11 days they are given with i.v. ovalbumin leading to
shock.
• It is counteracted by corticosteroids and i.v. disodium
cromoglycate.

10. METHODOLOGY:
female Sprague dawley rats (120- 150 g)
Injected i.m with 10mg/kg of ovalbumin
simultaneously
With Bordetella pertusis suspension i.p
IgE Ab migrates to surface of mast cells and basophilic granulocytes
11 days
i.v. injection of ovalbumin 25mg/kg.

11. 18 hours before given with corticosteroids and disodium cromolglycate
Ag-Ab complex forms on the surface of mast cell
Release Histamine, 5-HT, etc COUNTERACT
SHOCK
MORTALITY(80%)

12. EVALUATION:
Symptoms of shock scored and mortality recorded, compared with
untreated animals.

13. 2. Anti- anaphylactic activity in guinea pigs
(SCHULTZ DALE reaction)
Guinea pigs are sensitized against egg albumin
3 weeks
release histamine
Contraction of smooth muscle

14. Methodology:
guinea pigs (300- 400g)
alum precipitated egg album
in (1mg/ml) in saline.
stirred
kept in room temperature
0.125 ml alum egg albumin to foot pad and 0.5ml SC
4 weeks

15. Killed using anaesthetic ether
Ileum dissected out and cleaned
Mounted on organ bath(Tyrode solution 37 degree Celsius)- stabilize
for 15 mins
Barium chloride
the tissue respond to spasmogen are selected
3 bath selected

16. test group control group
std group
administered ovalbumin
Contractions recorded on physiograph