Delayed hypersensitivity. A critical evaluation of five recall antigens in a large reference population.

The reactivity to five recall antigens, candida, mumps, PPD, varidase and trichophyton and the corresponding diluents was tested in 840 healthy persons aged between 17 and 101 years. Candida antigen was tested in a lower (l) and a higher (h) dose. The size of reactions did not follow a Gaussian distribution and we therefore used the 10th and 5th percentiles instead of standard deviation to define the limits between positive, weak and negative reactions. The number of positive reactions to each of candida-h, mumps, PPD and varidase was between 80 and 95 per cent in patients less than 60 years of age and above this age it varied between 0 and 85 per cent. The number of positive reactions to candida-l and trichophytin was low in all ages. The reactivity was regarded as normal if there was a positive reaction i.e.sum of right angle diameters >10 mm to atl east one antigen, relatively anergic if there was only a weak reaction (7-9 mm) and anergic if there was a negative reaction (0-6 mm) to all antigens. A normal reaction was found in 100 per cent of subjects up to 60 years of age, and in 95 per cent up to 30 years. Among those with normal reactivity, positive results were found with candida-h alone in between 67-93 per cent, candida-h + mumps between 92-100 per cent and candida + mumps + PPD in 100 per cent irrespective of age.