Abstract
This paper deals with the ability of various adrenal cortex extracts to raise the resistance of normal guinea pigs to injections of diphtheria toxin, and to inactivate the toxin in vitro. It is part of a research program 1 directed toward an understanding of the mechanism of natural resistance, and is an attempt to determine whether the adrenal cortex resistance factor can be isolated by the same chemical procedures used in extracting the vital hormone.
The 5 methods of corticoadrenal lipoid fractionation used are very briefly indicated on an accompanying composite chart (Table I). They have been studied by one of us (R.L.Z.) for a number of years and most of the essential principles have been reported by workers on adrenal cortex extracts.2-8 In addition to our own preparations, we used Eschatin (Parke, Davis & Co.) and 2 batches of corticoadrenal hormone kindly given us by Dr. Pfiffner of the Department of Biochemistry. One of his extracts had 100 dog units 9 and the other 40 dog units per cc.
The diphtheria toxin employed was from one batch of stabilized filtrate containing from 400-450 m.l.d. per cc., so that 1 cc. of a 1/200 dilution included at least 2 minimal lethal doses.
Over 150 guinea pigs were used as indicated in the tables and in the description of our results. Since many of the control animals accompanied the individual experiments with both corticoadrenal extracts and vitamin C, some of them were listed individually in the previous paper of this series. 1 In the present paper they are given in the first lines of Tables II, III and IV.
Intracutaneous tests with 1/50, 1/100, 1/200 and 1/500 m.l.d. of diphtheria toxin were made on 46 light colored, 350 gm. guinea pigs. Certain fractions of adrenal cortex extract, when given in various doses (depending upon their toxicity) 24 hours before toxin, diminished or prevented the characteristic skin reactions (Table II). Results with other fractions did not differ greatly from those observed in the 16 controls.
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