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The antigenic relationships of Ambrosia artemisaefolia, Ambrosia elatior, Ambrosia psilostachya, and Ambrosia trifida were studied using the techniques of gel diffusion and pas­sive cutaneous anaphylaxis. Ten gram samples of defatted pollen were extracted for 7 2 hours with Coca's solution.

Each pollen extract was standardized on the basis of total nitrogen content per ml of extract using the Kjeldahl method. Antisera were prepared by injections of the pollen extract in Freund' s complete adjuvant. Rabbits were immunized subcutaneously against each pollen extract and antisera were collected five to six weeks after immunization. Gel diffusion analysis was performed by first pouring the diffusion media into plastic petri dishes previously treated with an anti-wetting agent. Wells were cut in the agar using gel cutters of various patterns. Wells were filled with the reactants and the plates allowed to incubate at 37 C for varying lengths of time. After maximum development the precipitation patterns were recorded by either drawing or photographing them. Passive cutaneous anaphylaxis was performed using male Swiss-Webster mice that were clipped one day prior to use. The mice were sensitized with 0.05 ml antisera, and after a thirty minute latent period, were challenged with 0.25 ml of an antigen-dye mixture. The animals were killed thirty- minutes after antigen challenge, skinned, and the reactions read on the internal side of the skin. Gel diffusion revealed complete identity between

antigens of Ambrosia artemisaefolia and Ambrosia elatior. Ambrosia psilostachya revealed one similar antigen in common with Ambrosia artemisaefolia and Ambrosia elatior. Ambrosia psilostachya and Ambrosia trifida shared no identical antigens. One antigen of Ambrosia trifida demonstrated a reaction of partial identity with an antigen of Ambrosia artemisaefolia and Ambrosia elatior. Passive cutaneous anaphylaxis demonstrated the existence of cross reacting antibodies between all four species of ragweed pollen. It was shown that more antigen was required to evoke a positive passive cutaneous anaphylaxis reaction with heterologous antibody than with homologous antibody, but subtle differences between species could not be deter­mined using this technique.



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UNM Biology Department

First Committee Member (Chair)

John Beakley

Second Committee Member

James Booth

Third Committee Member

William Martin

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