Immunotherapy decreases skin sensitivity to ragweed extract: demonstration by midpoint skin test titration.
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Humans↗
Biomedical subjects
A Khattignavong
Publications and source records attributed to A Khattignavong.
Immunotherapy decreases skin sensitivity to cat extract.
In 22 patients with cat asthma who were highly sensitive to cat, we compared, double-blind, the effects of immunotherapy with cat-hair and dander extract (11 patients) with effects of placebo (11 patients). Patients matched by intradermal skin test titration, leukocyte histamine release, and the doses of both cat extract and methacholine required for 20% fall in FEV1 were randomly assigned to one of the two treatment groups. Immunotherapy doses were increased to a maintenance dose of 4.56 Food and Drug Administration (FDA) units of Fel d I or if maintenance dose was less, to the highest tolerated dose. Before and during immunotherapy, we measured by intradermal titration the dose of cat extract, in FDA units of Fel d I equivalents, required for (1) 2+ end point (wheal diameter, greater than or equal to 10 mm; erythema diameter, 20 to 30 mm) and (2) 20 mm end point (erythema diameter, 20 mm). By prick skin test, we measured (1) the dose of cat extract that produced a wheal equal in area to that produced by histamine, 1 mg/ml, (2) the doses of cat extract that produced a wheal 22 mm2 in area, and (3) the sum of the wheal areas produced by five prick tests to 23.8, 7.1, 2.4, 0.7, and 0.2 FDA units per milliliter of Fel d I, respectively. After 1 year of treatment, in comparison to control patients, treated patients had significant increases in the ratio 1 year value/pretreatment value for the doses of cat extract required for intradermal test end points 1 and 2 (p less than 0.01), for prick test end point 1 (p less than 0.01), for end point 2 (p = 0.015), and significant decreases in this ratio for prick test end point 3 (p = 0.015). Treated patients also had significant increases in cat extract required for a 20% fall in FEV1 (p less than 0.01), in IgG antibodies toward whole cat extract, Fel d I and cat albumin (p less than 0.001), and in IgE antibodies toward whole cat extract, (p less than 0.01). Thus, a decrease in skin sensitivity to cat extract demonstrated by both intradermal and prick methods occurred in patients after 1 year of immunotherapy with cat extract at a time when bronchial sensitivity to cat extract was decreased and IgG and IgE antibodies toward cat extract were increased.
Allergens↗
Immunotherapy for cat asthma.
In 22 patients with cat asthma who were highly sensitive to cat, we compared, double-blind, the effects of immunotherapy with cat-hair and dander extract (11 patients) with effects of placebo (11 patients). Patients were matched by the dose of the cat extract expressed in Food and Drug Administration (FDA) units of Fel d I (previously called cat allergen 1) required for end point reaction in intradermal skin test end point titration (STEPT), for in vitro leukocyte histamine release (LHR), and for the dose of cat extract producing a 20% fall in FEV1 (cat-extract PD20) in bronchoprovocation test. Patients were matched also for bronchoprovocation dose of methacholine producing a 20% fall in FEV1 (methacholine PD20). Patients were randomly assigned to one of two treatment groups. During immunotherapy, doses were increased to maintenance dose of 4.56 FDA units of Fel d I, or, if this were less, to the highest tolerated dose. Systemic reactions to cat-extract immunotherapy were mild and infrequent. Before and during immunotherapy, we measured (in FDA units of Fel d I) cat-extract PD20, cat-extract intradermal STEPT, cat-extract in vitro LHR, serum levels of cat IgG and cat IgE, and methacholine PD20. After they had received 1 year of immunotherapy, patients receiving cat extract, in comparison to patients receiving placebo, had decreased cat-extract PD20 (p less than 0.01), diminished responses to cat-extract intradermal STEPT (p less than 0.025), increased IgE antibodies toward cat extract (p less than 0.01), increased IgG antibodies toward cat extract, Fel d I, and cat albumin (p less than 0.001), but no significant change in cat-extract in vitro LHR or in methacholine PD20. We conclude that cat-extract immunotherapy was well tolerated, significantly decreased skin and bronchial responses to cat extract, and significantly increased IgE antibodies to cat extract and IgG antibodies to cat extract, Fel d I, and cat albumin.
Adult↗