Enhancement of delayed skin hypersensitivity by neuraminidase in cancer patients

Delayed skin hypersensitivity to specific antigen was enhanced when the antigen was given intradermally with Vibrio cholerae neuraminidase in sensitive subjects. No enhancement of skin test response was seen when inactivated enzyme was used. Neuraminidase exhibited no effect on negative skin-test response in non-sensitive recipients and no reaction at the site of this enzyme was observed in any instance, suggesting that the enhancement effect is immunological in nature.