Preliminary Observations on the Frei Test in Lymphogranuloma Inguinale

Abstract

Since the Frei test is considered to be allergic in nature a passive transfer in the sense of Prausnitz and Küstner was attempted. Five non-tuberculous individuals who had reacted negatively to Frei antigens and one Rhesus monkey were intradermally inoculated in different skin areas of the back with 0.1 cc. Frei antigen, 0.1 cc. inactivated normal human serum, 0.1 cc. sera of typical cases of Lymphogranuloma inguinale and 0.1 cc. mixtures of normal human serum and Frei antigens. Twenty-four hours later 0.1 cc. of a potent Frei antigen was injected into the same areas but with negative results. This was repeated in 3 patients at the end of 1 and of 2 months, again with negative findings.

The Frei test as now used is often difficult to evaluate. It is evident from the reactions that the antigen far exceeds the necessary dose for a more specific and less potent reaction and that the antigens may also contain non-specific factors.

Samples of Lymphogranuloma inguinale pus were dried in vacuo above anhydrous CaCl₂, ground to a fine powder and weighed. It was found that 0.1 gm. suspended in 10 cc. of physiologic salt solution (1:100) and heated at 60°C. gives an excellent antigenic emulsion. A positive reaction was secured in one case in a dilution as high as 1:20,000.

However, the grading off usually occurred between 1:5,000–1:10,000. Therefore, the test can be performed with much more dilute antigens than are at present in use. High speed centrifugations of the antigens yielded non-reactive supernatant liquids. Berkefeld filtrates also gave negative results.

Acidification or alkalinization of the dried antigen with N/100 HCl or N/100 NaOH and neutralization prior to injection did not destroy the reacting factors. The residual lipoids from an alcohol ether extraction (3:1) were non-reactive.