Photo-inactivated allergens. I. Preparation, physicochemical and biological properties

Modified forms of allergen immunotherapy

There have been many attempts to modify allergens and thus to improve upon conventional immunotherapy, which has been proved effective but has several drawbacks. These include the risk of systemic reactions and the time and cost involved. The modifications have taken three major approaches. One approach, to impede allergen release from the site of deposition, has met with limited success. An example is alum precipitation, which has modestly reduced the number of injections and incidence of systemic reactions. A second approach, to suppress specific IgE production and to induce specific tolerance, has not been successful in man. The third approach, to reduce allergenicity while retaining immunogenicity of allergens, has been the most successful and appears to have the most promise. One example is polymerized allergens, which have been shown to be safe, efficacious, and immunogenic in multiple clinical trials. Other examples include allergoids and glutaraldehyde-treated, tyrosine-adsorbed allergens.

Animal dander allergy

In a group of twenty-three atopic patients skin tests were performed with the dander allergens of horse, cat and guinea-pig, and with house dust and Timothy pollen allergens. A good agreement was observed between positive skin reactions and the results of RAST with these various allergens. In a number of cases, positive skin reactions were not related to the clinical histories. Likewise, positive RAST scores in several instances proved clinically meaningless. In patients with history-related skin reactions better correlation with RAST was observed. In such patients, skin reactions with photo-inactivated allergens remained strongly positive.

Inactivation of heamolytic complement by house dust allergen in the serum of children with atopic diseases

Purified house dust allergen has been employed for screening the susceptibility to inactivation of haemolytic complement in the blood serum of atopic children and control subjects. Fluid phase complement in the control group of children was more sensitive to allergen-induced inactivation than observed in a normal adult population. Though the mean complement sensitivity indices in all groups of patients were below the valve for the control group, there was considerable statistical overlap. The serum complement sensitivities were in no way related to the clinical manifestations. The results of the complement test were not correlated to the total IgE levels, the RAST scores nor the skin reactions with house dust allergen. Some evidence for the in vivo involvement of the complement system in childhood atopic allergy was provided: the mean C3 proactivator level was significantly lower in atopic children, than in the control group; the mean C4 level in children with bronchial asthma and in children with atopic dermatitis was significantly depressed. A significant positive correlation between the serum C4 levels and allergen-complement sensitivities in children with both bronchial asthma and atopic dermatitis was observed.

Immunological studies in vitro and in vivo of children with pollenosis given immunotherapy with an aqueous and a glutaraldehyde-treated tyrosine-absorbed grass pollen extract

Ten patients treated with an aqueous Timothy grass pollen extracts and given monthly maintenance doses were compared to ten patients given a glutaraldehyde-treated tyrosine-adsorbed grass pollen extract as five weekly injections pre-seasonally. There were four non-treated controls. Both treated groups showed equivalent increases of total IgE, Timothy-specific IgE, and IgG, but the concentrations of Timothy-specific IgG antibodies were sustained only in the patients receiving maintenance therapy. An increase of IgE and RAST titres during the pollen season were obtained in all three groups. No consistent changes were seen in the results of leucocyte histamine release tests and naso-conjunctival provocation tests from spring to autumn. A Sepharo-protein A technique was used for the estimation of Timothy-specific IgG antibodies. The results obtained with this technique correlated excellently with those of the Farr technique and a double-antibody technique.

Blood group activity of allergenic preparations

Haemagglutination-inhibition studies showed that several different allergenic preparations exhibit A and B blood group activity. Most products displayed A-specificity, less often B-specificity; the inhibition titers were usually low. No correlation was evident between isoagglutination-inhibition titers and the complement-consuming capacity or skin-reactivity of the allergens. Absorption of A- and B-isoagglutinins from human serum did not affect the complement consumption by house dust allergens. Hapten-inhibition studies confirmed the non-participation of blood group antibodies in allergen-induced complement consumption. The observed inhibition by D-glucosamine is attributed to a partial structural homology with the lysine-sugar site on house dust allergens.