Recent improvements in the Kahn precipitation test have given a new impetus to the study of the serum diagnosis of syphilis with this method. All reactions—weak as well as strong—are now completed within some minutes after mixing serum with antigen. Constancy of results in the hands of different workers has been made possible by standardizing the various steps of the technic. Aside from the routine procedure with serum, the test offers a special method for the quantitative determination of the reacting substances in syphilitic serum, applicable especially to the serologic study in cases in which the patient is undergoing specific treatment, a "presumptive" procedure of unusually high sensitiveness applicable to special cases, and a procedure for testing spinal fluids.1
No less important than the practical value of the Kahn precipitation test as a diagnostic agent is the applicability of the test to research in syphilis. We know almost as
KEIM HL, KAHN RL. CLINICAL STUDIES ON THE KAHN REACTION FOR SYPHILISI. DIAGNOSTIC VALUE OF TEST. Arch Derm Syphilol. 1924;10(6):722–733. doi:10.1001/archderm.1924.02360300056004
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