Abstract
Neither the fundamental mechanism of the Frei reaction, which until recently was the only basis for the certain diagnosis of lymphogranuloma venereum, nor the nature of the reagent in the antigen which provokes a positive Frei test has yet been clearly defined. It has been observed that high-speed centrifugation of certain Frei antigens yields dermally active sediments containing virus elementary bodies 1 but nonreactive supernatant fluids. 1 , 2 Furthermore, the passage of Frei antigens through Berkefeld filters 1 , 2 or Seitz K discs 1 was found to reduce greatly or, more commonly, to abolish completely the dermal activity of the filtrate; it should be noted that Seitz K filter? are permeable even to bacteria. These observations have led Findlay to the conclusion that the Frei test demonstrates an allergic reaction due to the presence of the elementary bodies of the virus in the material injected.
It has previously been shown that by propagation of the agent of lymphogranuloma venereum in the yolk-sac of the developing chicken embryo 3 or in the lungs of mice 4 there are obtained quantities of virus far greater than those present in other tissues. Inactivated suspensions of elementary bodies derived from the yolk-sac, and separated from tissue constituents by differential centrifugation, have been successfully employed as antigens for the Frei test 5 and for the demonstration of complement-fixing properties in the serum of persons infected with the virus; 6 in the latter test suspensions of virus from mouse-lung have also been used.
Complement-fixation tests 6 have been performed in which falling dilutions of selected lymphogranulomatous human sera, known to fix strongly, were titrated against falling dilutions of antigen in the form of suspensions of elementary bodies sedimented from yolk-sac or mouse-lung by high-speed centrifugation.
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