Isolation of tuberculin peptides from tuberculin purified protein derivative (PPD).

Tuberculin purified protein derivative (PPD) obtained from the filtrate of Mycobacterium tuberculosis was hydrolysed with proteinase, trypsin, or chymotrypsin. Each hydrolysate consisted of a tuberculin peptides mixture (TPM). From each TPM 16 fractions were obtained by ion-exchange chromatography on Dowex 50W-X8 but only one fraction was isolated from each of the 16 fractions which showed tuberculin activity in guinea pigs sensitized with M. bovis (bcg) or M. tuberculosis. This fraction was designated "purified tuberculin peptide" (PTP). The PTP fraction from the proteinase hydrolysate (PTP-proteinase) was rechromatographed on Dowex 1-X2 and two tuberculin peptide fractions having molecular weights of 3200 and 12,000 were isolated. The potency of these two fractions was assessed in guinea pigs sensitized with M. bovis (BCG) and with M. tuberculosis and they were approximately 4 to 7 times more potent than either the international standaCG and of at least equal potency to either PPD-S or Connaught PPD in guinea pigs sensitized with either M. kansasii, M. scrofulaceum, M. intracellulare, or M. avium whereas very little if any cross-reactivity was elicited by these two fractions. This lack of response indicates that either fraction could be used as an aid to differentiate between sensitization due to M. tuberculosis or M. bovis and sensitization attributed to other mycobacteria.     

Causes of para-allergy to tuberculin

Experiments on 56 rabbits infected with microorganisms of the genera Mycobacterium, Nocardia and Rhodococcus revealed that in response to the action of different antigens used T and B systems of immunity induced synthesis of antibodies reactive with nonspecific antigens (mycobacterial antigens, tuberculin). In some cases the statistically significant correlation between the dynamics of blast transformation and the specific lysis of lymphocytes in animals with Nocardia and Rhodococcus infections (in comparison with the controls) was determined when P.P.D. tuberculin was used as specific antigen. In the rabbits sera infected by Nocardia and Rhodococcus complement-fixation and hemagglutination antibodies to mycobacterial antigens were detected. These rabbits also exhibited skin reaction to P.P.D. tuberculin. The presence of common group-specific antigens in Nocardia and Rhodococcus, as well as in mycobacteria, determined the capacity of the former to sensitize experimental animals to tuberculin, with should be taken into consideration in making the allergic test to tuberculosis.