The allergenic potencies of samples of two commercial Alternaria tenuis extracts stored under various conditions were compared at 3 months intervals over a period of 1 year. Aliquots of the extracts at 5.12 mg/ml were maintained in: saline; 50% glycerol-saline mixture; 0.4% phenol-saline; 0.4% phenol-saline containing 0.03% human serum albumin, and samples were also kept in lyophilized form. The samples were stored at -20, 4, 24, 37 and 56 degrees C. Their potency was measured by radioallergosorbent inhibition assay and by mouse IgE passive cutaneous anaphylaxis (PCA) tests. The lyophilized extracts fully maintained their activity at all temperatures for 12 months. Aqueous extracts with or without preservatives also maintained their potency if stored at -20, 4 and 24 degrees C, but showed a significant loss of PCA activity at 56 degrees C, after 3 months. A deleterious effect of phenol was observed in one of the extracts stored at -20 degrees C for 3 months, by PCA tests. The use of preservatives to retain potency over a period of 12 months is therefore unnecessary and may be deleterious. The results indicate that, while storage of A. tenuis in a lyophilized form is best at all temperatures, aqueous extracts are also remarkedly stable when stored at -20, 4 and 24 degrees C, over a 12-month period.

The effects of an extract of the saprophytic mold, Alternaria tenuis (AT-CE) on the humoral response to a ragweed allergen extract (DWSR), ovalbumin and sheep red blood cells (SRBC) was investigated in female Wistar rats. Animals pretreated with 100 micrograms or 2 mg AT-CE showed enhancement (p less than 0.05) in the reaginic response (IgE antibody) to DWSR at 25 and 18 days postimmunization. On the other hand, animals posttreated with AT-CE showed substantial reduction in anti-DWSR IgE antibody response. Contrasting results were obtained when ovalbumin was used as an immunizing antigen. There was a remarkable enhancement in the reaginic response to ovalbumin in rats pre- or posttreated with 10 micrograms of AT-CE. Pretreatment with AT-CE did not affect the hemagglutination titers to ovalbumin, while posttreatment with 100 micrograms or 1 mg AT-CE increased the hemagglutination titers of IgM antibody. There was a significant reduction in hemagglutinin, and hemolysin titers to SRBC in animals pretreated with all concentrations of AT-CE; at day 21, suppression was noted in animals pre- or posttreated with all concentrations of AT-CE. On the other hand, greatly increased hemagglutination titers were found in animals posttreated with 100 micrograms or 1 mg AT-CE. Hence, enhancement and suppression can both occur depending on the dose and time of administration of AT-CE together with the nature of the immunizing antigen.

Extracts of Alternaria tenuis and Alternaria solani were separated into dialyzable (molecular weight less than 10,000) and non-dialyzable forms. The latter was further fractionated by gel filtration through Sephadex G-100 followed by ion-exchange chromatography on DEAE-cellulose. The dialyzable material was fractionated by gel filtration through Sephadex G-50. The allergenic activities of the fractions obtained from the A. tenuis extract was measured in vitro by the radioallergosorbent test assay and the allergenic potency was measured by radioallergosorbent test inhibition assay. Allergenic activity was detected in most of the non-dialyzable fractions, the majority of the activity being in the last G-100 fraction (MW approximately 20,000) which was predominantly protein in nature. The same component may be responsible for the activity found in the dialyzate and its first G-50 fraction since the immunodiffusion studies indicated that the last G-100 fraction has antigenic components in common with those of the first G-50 fraction. In addition, cross-reactions between A. tenuis and A. solani extracts show that the two species share common antigenic determinants.