Immune approaches in tuberculosis therapy: a brief overview.

TB is typically caused by Mycobacterium tuberculosis, a symbiotic bacterium present in one-third of the world's population. There any many factors triggering overt clinical disease in a small proportion of humans. In our view the major role in the process is played by the host's immune response, especially self-directed, destructive inflammation. Conventional chemotherapy produces bactericidal or bacteriostatic effects, but immunopathological changes can only be corrected by immunotherapy. Various attempts have been made to identify the optimal immune intervention. Some have shown promising effects, but many have failed. It is commonly believed that the field started in 1890: the year Robert Koch announced his tuberculin therapy. In the Pên Ts'ao Kang Mu, classical Chinese materia medica, published during Ming dynasty, Li Shi Chen (1518-1593) recommended, as a remedy for hemoptysis, to collect from the sputum "…blood lumps, roast them till they are black, and take then them as a powder". In retrospect, this is perhaps the earliest recorded reference relating to immunotherapy of TB with heat-killed mycobacteria. Modern science is obviously geared toward more palatable approach, but without hindsight from often disdained empirical evidence no progress can be made. The clinical experience from various trial and error processes is briefly discussed in this review.

Phase IIb randomized trial of adjunct immunotherapy in patients with first-diagnosed tuberculosis, relapsed and multi-drug-resistant (MDR) TB.

Placebo-controlled, randomized, phase 2b trial was conducted in 34 adults comprising 18 first-diagnosed (52.9%), 6 relapsed (17.6%), and 10 MDR-TB (29.4%) cases to investigate the safety and efficacy of an oral immune adjunct (V5). The immunotherapy (N = 24) and placebo (N = 10) arms received once-daily tablet of V5 or placebo for one month in addition to conventional anti-TB therapy (ATT) administered under directly observed therapy (DOT).The enlarged liver, total bilirubin, erythrocyte sedimentation rate, lymphocyte and leukocyte counts improved significantly in V5 recipients (P = 0.002; 0.03; 8.3E-007; 2.8E-005; and 0.002) but remained statistically unchanged in the placebo group (P = 0.68; 0.96; 0.61; 0.91; and 0.43 respectively). The changes in hemoglobin and ALT levels in both treatment arms were not significant. The body weight increased in all V5-treated patients by an average 3.5 ± 1.8 kg (P = 2.3E-009), while 6 out of 10 patients on placebo gained mean 0.9 ± 0.9 kg (P = 0.01). Mycobacterial clearance in sputum smears was observed in 78.3% and 0% of patients on V5 and placebo (P = 0.009). The conversion rate in V5-receiving subjects with MDR-TB (87.5%) seemed to be higher than in first-diagnosed TB (61.5%) but the difference was not significant (P = 0.62). Scoring of sputum bacillary load (range 3-0) at baseline and post-treatment revealed score reduction in 23 out of 24 (95.8%) V5 recipients (from mean/median 2.2/3 to 0.3/0; P = 6E-010) but only in 1 out of 10 (10%) patients on placebo (1.9/1.5 vs. 1.8/1; P = 0.34). No adverse effects or TB reactivation were seen at any time during follow-up. V5 is safe as an immune adjunct to chemotherapeutic management of TB and can shorten substantially the duration of treatment.