Nature of the Antibodies for Sheep-Cells in Infectious Mononucleosis

Abstract

The sheep-cell antibodies in infectious mononucleosis serums have been called heterophile or Forssman antibodies by several investigators but since, as previously pointed out, 1 , 2 , 3 , 4 the Forssman character of these antibodies is questionable, further studies on their nature are necessary. To this end the relationship of alcoholic extracts of beef- and sheep-cells to the sheep-cell antibodies in infectious mononucleosis and in several Forssman heterophile serums has been determined.

Extracts were prepared by treating one volume of packed cells with 5 volumes of alcohol for 12 hours at room-temperature followed by 8 hours in a mechanical shaker, filtering, and concentrating the filtrate to one-half its volume at 37°C. Equal volumes of this extract and saline were mixed and the alcohol removed by evaporation at 50°C. The turbid suspensions prepared in this manner were used to inhibit the hemolysis of sheep-cells by the various normal and immune serums noted in Table I.

In the inhibition-tests 0.25 nil. of the alcoholic extract in dilutions ranging from 1:1.25 to 1:320 was placed in a series of tubes; 0.25 ml. of the normal or immune serum containing sufficient hemolysin to hemolyse completely the dose of sheep-cells in 10 minutes, and 0.25 ml. of guinea pig-complement diluted 120 was added to each tube in the series. Triplicate controls with 0.25 ml. of saline substituted for the extract were used in each test. After 15 minutes'incubation at 37°C. in a water-bath, 0.25 ml. of a 1.0% sheep-cell suspension was added to each tube. When all 3 control tubes showed complete hemolysis the degree of hemolysis in the tubes containing the extract was noted. Ten minutes later a second reading was taken.