The Relation of Radiation Dosage to Enhancement, Depression, and Recovery of the Initial Forssman Hemolysin Response in Rabbits

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Abstract
In the present study 72 series involving 922 rabbits received a single total body X-irradiation within a range of 25 r to 700 r and a single intravenous injection of 108.3 sheep red blood cells from 2 days before to 2 months after radiation. A control series consisted of 164 nonirradiated rabbits. Antigen given within 2 days before the various doses of X-rays resulted in a significant enhancement of titer. When antigen was given within the same length of time after irradiation, enhancement was replaced by a marked depression of titer. Recovery occurred thereafter. Enhancement was of 2 types. Type 1 was characterized by a stimulation of the immune process, i.e., by a normal or above normal rate of hemolysin production operating during a normal length of time, and type 2 was characterized by a retardation of the immune process, i.e., by a subnormal rate of production continued over a long time. Type 1 occurred when antigen was injected within 2 days before small doses of 25 r to 100 r. It also occurred when antigen was injected 1 month after the small doses and 2 months after intermediate doses of 200 r and 300 r. Thus, the wave of stimulation that followed irradiation during recovery occurred later as the X-ray dose was increased. Type 2 occurred when antigen was injected within 2 days before large doses of 500 r to 700 r. In general, the various parameters used to measure the rate and amount of hemolysin produced responded consistently with the controls during type 1 enhancement, were reversed during depression, and were modified during type 2 enhancement.