We previously demonstrated that a single
intradermal injection of 10(9) irradiation-killed M. vaccae, given 1 month after starting
chemotherapy, caused significant changes in responses to mycobacterial
antigens. Amongst 38 patients with
pulmonary tuberculosis, 29% had lymphocytes responding to common myocobacterial
antigens after the injection, compared with only 11% of 49 similar patients after an injection of saline (p less than 0.03). To increase the proportion of responders to these
antigens, six modifications of the potentially immunotherapeutic injection, randomized with
injections of saline, have been assessed by biochemical, clinical, haematological, immunological and radiological criteria. Subsequent lymphocyte proliferation to mycobacterial
antigens enabled the modifications to be ranked in order of efficacy.
Tuberculin plus
murabutide plus 10(9) irradiated M. vaccae (36% of 25), an autoclaved preparation of 10(9) M. vaccae (45% of 22), and 2 x 10(9) irradiated M. vaccae (75% of 12) were the most effective. Antibody responses in several
IgG subclasses to mycobacteria, but not streptococci, were also significantly increased by the most effective modifications over the 8 weeks following injection. Detailed radiological study showed that use of the autoclaved bacilli was followed by a delay in clearing of consolidation, but by better closing of cavities than was found in the control group, suggesting enhanced, or altered, immunological activity around the lesions.