Tuberculin Reactions in Ankylosing Spondylitis Compared with those in other Rheumatic Diseases.

Two independent sets of observations made at the Devonshire Royal Hospital have both suggested that tuberculin sensitiveness in cases of spondylitis ankylopoietica tends to excess. The phenomenon has been noted recently during von Pirquet testing of assorted rheumatic patients, and formerly' as part of a study of the disease itself. Moreover, such patients have sometimes been treated by vaccination with a fluid containing autolysed tubercle bacilli (the Ponndorf cutivaccine), whose effects in varying degree of flush, cedema and scaling resemble those of a tuberculin reaction. It was therefore thought desirable to determine whether ankylosing spondylitis is in fact associated with excessive tuberculin sensitiveness. The background of ascertained fact with regard to tuberculin tests2 in so far as it specially affects the results below may be recapitulated as (1) the general positiveness of our population and (2) the lower levels in the young, in females and in wasting disease. The following procedure was adopted. Von Pirquet tests were performed and read at one, two and ten days by a single observer. Five insertions, made from above down on the volar surface of one forearm, consisted of nought, two, six, seventeen and fifty per cent. Old Tuberculin (Burroughs, Weilcome) in saline. The areas of swelling and flush were measured and noted at each of the three readings, and from the data thus obtained each patient's reaction was assigned to one of six classes-namely, 0 Negative, 1 Very Weak Positive. 2 Weak Positive, 3 Moderate Positive, 4 Strong Positive, 5 Very Strong Positive. Thus the figures 0 to 5 form a von Pirquet index, or rough quantitative estimate of the intensity of tuberculin response suitable for purposes of comparison.