From Big Medical Encyclopedia

CANA REACTION (R. L. Kahn, amer. the microbiologist, a sort in 1887) — one of the most widespread serological tests for the diagnosis of syphilis. It is for the first time described by Kan in 1922 then as a standard method in 1924. To. the river is founded on a phenomenon of loss of precipitated calcium superphosphate from mix of lipoid extract of heart of a bull and blood serum of the person sick with syphilis; under the same conditions mix of extract and serum of the healthy person remains transparent.

Antigen alcoholic holesterinizirovanny extract from a myocardium of a bull serves. Antigen is titrated, adding to constant quantity it (1 ml) various doses (from 0,6 to 1,2 ml) of 0,9% of solution of sodium chloride.

About a caption of antigen judge by the smallest amount of solution of sodium chloride, a cut, being added to 1 ml of antigen, causes formation of the unit disappearing at the second addition of 0,9% of solution of sodium chloride. Standard antigen 1,1 ml of 0,9% of solution of sodium chloride produce with a caption 1 ml of antigen +.

Statement of reaction

To 1 ml of antigen quickly flow 0,9% solution of sodium chloride, and pour mix from a test tube in a test tube of 12 times. Within 10 min. the antigenic emulsion «ripens» then it is stirred up and spill a micropipet for each serum on a bottom in three test tubes in doses 0,05; 0,025 and 0,0125 ml. In each test tube add 0,15 ml of the serum which is warmed up 30 min. at t ° 56 °. The support is stirred up within 3 min. in the shaker then add 0,9% solution of sodium chloride in doses of 1 ml, 0,5 ml and 0,5 ml respectively. After stirring consider results immediately and in 15 min., designating them depending on degree of precipitation as «positive» (4+, 3+ and 2+), «doubtful» (+ and ±) and «negative» (—). The arithmetic average of indications of three test tubes is the general result. In the USSR reaction is put in one test tube with a dose of antigen of 0,025 ml.

At sharply positive takes it is possible to apply quantitative reaction of Kan, to-ruyu put with cultivations of serum: 1:1, 1:5, 1:10 and T; in doses on 0,15 ml and with a dose of the antigen of 0,01 ml divorced on a caption of 1 ml of antigen of +1 ml of 0,9% of solution of sodium chloride. The greatest cultivation of serum yielding a positive take defines a caption of serum.

In case of uncertain or doubtful results it is recommended to put additional tests: with doses serums 0,05 and 0,1 of ml, with antigen in a dose of 0,05 ml and with cultivations serums 1:4, 1:8 and 1:16 in doses of 0,05 ml and with a dose of antigen of 0,0125 ml. If results of each testing are obviously positive, reaction is specific.

Kan's reaction with cerebrospinal liquid

Owing to trace amount of reagins in cerebrospinal liquid reaction is put with its globulinovy fraction divorced in 0,1 volume of 0,9% of solution of sodium chloride. For this purpose to 1,5 ml of cerebrospinal liquid add 1,5 ml of saturated solution of ammonium sulfate and mix is warmed up by 15 min. on the water bath at t ° 56 ° then centrifuge for sedimentation of globulin and suck away nadosadochny liquid. Add 0,15 ml of 0,9% of solution of sodium chloride to a deposit and transfer solution to a test tube from 0,01 ml of divorced antigen. After three-minute stirring add 0,5 ml of 0,9% of solution of sodium chloride and consider results. For sensitization of reaction Kan described also the «presumptive test» (presumptive test) allowing to put serodiagnoz with bigger degree of probability that it is reached by strengthening of antigen the sensibilizing reagent. Reaction is put in one test tube from 0,025 ml of divorced antigen. Results compare with indications of other reactions and about a wedge, data since at this method the percent of nonspecific reactions increases. In case of suspicion on the nonspecific results received in usual statement of reaction, the author offered «the confirmatory test» (verification test). For this purpose the precipitated calcium superphosphates received at reaction are tested for their ability to dispersion and for their relation to change of temperature. In the first case add 0,1 to three pilot test tubes; 0,1 both 0,15 ml of 20% of solution of sodium chloride and a support put for 10 min. in the water bath at t ° 37 °. In case of specific reaction precipitated calcium superphosphate is stable, and at false positive — is easily dispersed. In the second case reaction is put in parallel: in usual conditions at t ° 37 ° and at t ° 1 °. The specific result of reaction under these conditions almost does not change whereas the result of false positive reaction considerably amplifies at t ° 1 °, and at t ° 37 ° precipitated calcium superphosphate is easily dispersed.

On sensitivity To. the river is high on the list among the described precipitation tests and is in this respect most similar to reaction of Legislative Assembly — Vitebsk (see. Legislative Assembly — Vitebsk reaction ). To. the river was highly appreciated on two international serol, conferences — in Copenhagen (1928) and Montevideo (1930). In the USSR To. rubles apply since 1924; it enters a complex serol, the reactions accepted for a serodiagnoz of syphilis. Abroad it is applied much less often.

See also Wasserman reaction , Syphilis, diagnosis .

Bibliography: Caen R. L. Kan's reaction, the lane with English, M. — L., 1931; To a h n R. L. Recent significant changes in technic of Kahn presumptive and standard diagnostic flocculation tests, Vener. Dis. Inform., Suppl. 9, p. 183, 1939; it is e, Verification test in serology of syphilis, J. Lab. clin. Med., v. 28, p. 1175, 1943; about N of e, Serology with lipid antigen with special reference to Kahn and universal reactions, p. 327, Baltimore, 1950.

H. V. Nartsissov.