Studies on allergoids from naturally occurring allergens III. Preparation of ragweed pollen allergoids by aldehyde modification in two steps

Abstract

A new process for modifying heat-labile allergens, which employs a sequential two-step incubation at temperatures of 10.degree. C and 30.degree.-32.degree. C was devised. The process produced effective ragweed allergoids with low allergenicity and good immunogenicity, which makes them useful for the therapy of allergic humans. Modification with formaldehyde produced derivatives (formallergoids) that were about 10-fold less allergenic in allergic humans (as measured by leukocyte histamine-release assay), and similarly or more immunogenic in guinea pigs, than glutaraldehyde-modified allergens (glutarallergoids). Further analysis by RAST [radioallergosorbent test] inhibition showed that a ragweed formallergoid was 6-fold less reactive than a glutarallergoid with a pool of human IgE antibodies. The formallergoid had retained the ability to induce a wide array of antibodies against native ragweed antigens, since rabbit anti-formallergoid serum was able to recognize at least 12 different ragweed antigens, including AgE [antigen E]. Gel-filtration experiments showed that both the formallergoid and glutarallergoid materials contained polymers having apparent MW distributed around 260,000 and 230,000 daltons, respectively (approximate range 30,000-900,000 daltons). The immunochemical basis for the use of these allergoids in the therapy of allergic humans is suggested.