DIAGNOSTIC SKIN TESTING:
Puncture tests performed on 15 highly sensitive patients with 2 separate lots of 10,000 AU/ml Mite Extract (D. farinae) showed a mean sum of diameter wheal of 15.93mm ± 4.92 and a mean sum of diameter erythema of 63.70mm ± 16.46. Puncture tests performed on 10 highly sensitive patients with 10,000 AU/ml Mite Extract (D. pteronyssinus) showed a mean sum of diameter wheal of 17.00mm ± 3.39 and a mean sum of diameter erythema of 84.80mm ± 5.80. Intradermal skin test results in highly sensitive patients is shown below using the same lots as used in the puncture tests above.
AU/ml to elicit 50mm sum of
Diameter of Erythema Reaction
Extracts
Number of Patients
Mean
Range
D. farinae
15
1.328
0.0024-9.410
D. pteronyssinus
10
0.008
0.0009-0.0287
Puncture tests with the mite growth medium as control were negative in 15 patients sensitive to mite.
These products are used to determine a patient's sensitivity to specific antigens and aid in the diagnosis and treatment of atopic diseases. After a thorough history a decision can be made as to which allergens will be appropriate to use for testing. The recommended procedure is to initially perform puncture tests, then follow with intradermal tests. See recommended dosage below.
*
The negative intradermal control used for the 100 AU/ml concentration should contain 0.5% (v/v) glycerin.
SCRATCH OR PUNCTURE TEST:
Concentration
10,000 AU/ml
Dosage
0.05 ml
INTRADERMAL TEST:
A. Patients with a negative scratch or puncture test
Concentration
Dosage
1) 50 AU/ml or
0.02 ml
2) 100 AU/ml* if 50 AU/ml is negative
0.02 ml
B. Patients tested by intradermal only
Concentration
Dosage
0.05 AU/ml
0.02 ml
If negative repeat tests with stronger concentrations until a maximum of 100 AU/ml* is reached.
FREQUENCY OF ADMINISTRATION:
The number of skin tests applied at one time will depend on the particular patient and their allergic history. These tests should be performed and observed in 15 to 20 minutes. Additional tests may be applied in sequence. Perform tests on the anterolateral aspect of the upper arm on an area that permits the effective application of a tourniquet proximal to the site of the test. The skin at the site of injection should be disinfected with rubbing alcohol before testing.
Puncture testing: Apply one drop (0.05ml) of extract to the skin. Pierce the drop of extract and skin using a sterile hypodermic needle or vaccinating needle. Maintain the needle perpendicular to the skin surface and rock the needle back and forth to produce a small hole without bleeding. Do not rotate or gouge the needle. Remove needle from skin and wipe excess extract from skin surface.
Scratch testing: Using a scarifier or needle, make a scratch 1/16 inch long on the epidermis penetrating the outer cornified area but being careful not to draw blood. Apply one drop (0.05ml) of allergen to the scratch.
Intradermal testing: Use a separate sterile syringe (tuberculin type equipped with a 27 gauge by 3/8 inch needle with intradermal bevel) for each antigen. The tests are made by injecting 0.02ml of allergen into the epidermis. If the test has been performed properly, the solution should raise a bleb 2 to 3mm in diameter. If the bleb does not appear, the injection was made too deeply.
A negative control consisting of the same solution that the extract was prepared in should be applied to one of the sites in the same manner as the tests being performed. For example, the negative intradermal control should contain 0.5% (v/v) glycerin, if a 100 AU/ml concentration mite is used for intradermal testing. Histamine phosphate should be used as a positive control for evaluation of skin testing. Histamine phosphate is available from other manufacturers. See their directions for use, for recommended dosage and interpretation of results.
A positive reaction usually develops in 15-20 minutes. The positive response is a wheal and flare reaction that is larger than the negative control and judged on the size of the reaction. Scratch or puncture tests may not elicit as large and well defined reaction as the intradermal. (5)
The following system is recommended (8):
Reaction
Erythema
Wheal
0
<5mm
<5mm
+/-
5-10mm
5-10mm
1+
11-20mm
5-10mm
2+
21-30mm
5-10mm
3+
31-40mm
10-15mm or with pseudopods
4+
>40mm
>15mm or with many pseudopods
IMMUNOTHERAPY:
The following are two methods of injection therapy:
Pre-seasonal in which treatment is begun three months before seasonal difficulty begins and brought to maintenance dose by injections four to seven days apart and discontinued after that season ends.
Perennial treatment is the recommended mode of therapy in which the patient is, by injection therapy, brought up to tolerated maintenance dose and remains at that dose until amelioration of allergic symptoms occurs. Injections may be given at intervals of 4 to 7 days.
Allergenic extracts must be diluted before use. Normally immunotherapy can be started with a 1 AU/ml dilution. If a patient appears to be extremely sensitive, dilutions of the antigen can further be made before injections are started. The following are suggested procedures for making a proper dilution series. Recommended diluents contain 0.9% sodium chloride and 0.4% phenol as a preservative. Allergenic extracts should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
TEN FOLD DILUTION SERIES:
Extract
Volume
Extract
Concentration AU/ml
Diluent
Volume
Dilution
Concentration AU/ml
1 part
10,000 +
9 parts
= 1,000
1 part
1,000 +
9 parts
= 100
1 part
100 +
9 parts
= 10
1 part
10 +
9 parts
= 1
Perennial treatment may be started using the following dosage and dilution schedule. THIS SCHEDULE IS ONLY ILLUSTRATIVE AND HAS NOT BEEN SUBJECTED TO ADEQUATE OR WELL-CONTROLLED TRIALS TO DETERMINE EITHER ITS SAFETY OR EFFICACY.
Dose #
Dose Volume (ml)
Concentration
1
0.05
1 AU/ml
2
0.10
3
0.20
4
0.30
5
0.40
6
0 50
7
0.05
10 AU/ml
8
0.10
9
0.20
10
0.30
11
0.40
12
0 50
13
0.05
100 AU/ml
14
0.10
15
0.20
16
0.30
17
0.40
18
0 50
19
0.05
1,000 AU/ml
20
0.10
21
0.20
22
0.30
23
0.40
24
0 50
25
0.05
10,000 AU/ml
26
0.10
27
0.20
28
0.30
29
0.40
30
0 50
Gradually increase the dose as outlined in the schedule. If you give a dose that causes a mild local reaction manifested by warmth or redness, repeat the same dose. If the reaction is severe or systemic (manifested as hives, asthma, or hay fever), drop back a dose in schedule and build again. If a severe local reaction or a systemic reaction is again encountered, this should be considered more than the maximum tolerance for this patient. The maintenance dose is the largest dose that relieves symptoms without producing local reactions. The size and interval of doses will vary and can be adjusted as necessary. The normal interval between doses is 4 to 7 days.
