Active Sensitization of White Mice

Abstract

According to the only known studies dealing specifically with active anaphylaxis in mice, 1 , 2 3 a certain number of mice given a single prior injection of horse serum may be expected to show anaphylactic reactions when reinjected after the usual incubation period, but a higher proportion of the animals will react if 2 sensitizing injections have been made. In an attempt to attain the maximum degree of sensitivity, we gave different groups of normal mice, one 2, 3, or 4 intraperitoneal or intravenous doses of horse serum or egg white. The mice were then tested for sensitivity by the intravenous or intraperitoneal injection of the appropriate antigen at varying intervals after the last sensitizing dose, but usually after 12-21 days.

The results observed with mice sensitized to horse serum and tested by intravenous doses ranging between 0.5 cc. and 1.5 cc. are summarized in Table I. The effect of repeated sensitizing injections in increasing the liability to severe anaphylactic reactions seems clearly indicated. Only in groups of mice that received 3 or 4 antigen doses prior to the shocking dose were reactions observed in all the animals, and the best results were obtained with mice given 4 sensitizing inoculations. Severe or fatal reactions occurred in only about 40% of mice sensitized by 2 injections, but this percentage increased to 89% in the mice sensitized by 4 injections. In the latter group occurred the highest proportion of deaths (48%).

Intravenous and intraperitoneal injections apparently sensitized equally well.

Essentially similar results were obtained with mice sensitized to egg white.

Sensitivity was demonstrated as early as the 9th day, and was shown to persist at least as late as the 40th day, after the last of 2 or more sensitizing injections. Neither the number nor the severity of reactions was apparently influenced by varying the incubation period between the 12th and the 23rd day.