Role of IgG fractions with high isoelectric points in the thymol turbidity test in syphilis. Evidence for an increase in basic IgG in early syphilis.

It is demonstrated that IgG fractions with isoelectric points above 7.6, isolated from pooled syphilitic sera, are able to elevate the thymol turbidity. The effect increases with increasing isoelectric points of the isolated fraction. IgG from individual syphilitic patients exerts a stronger effect on the thymol turbidity than normal IgG. It is concluded that elevated amounts of these basic immunoglobulins are present in the sera of syphilitic subjects.