Immunology of bacille Calmette-Guérin and related topics.

Abstract

This supplement is based on a workshop held in Toronto, Ontario, on 11-13 July 1994, at the site of the sponsor, PasteurMerieux-Connaught Canada. The 3-day workshop focused on immunologic responses to BCG, its use in the prevention of tuberculosis and in the treatment and prophylaxis of bladder cancer, and its potential applications for other cancers. This workshop presented an exciting opportunity to bring together 2 distinct groups of researchers: those in infectious diseases and immunology and those in urologic oncology. It was rare to have these 2 groups in the same room talking together, but this workshop represented an important opportunity for both groups, since the mode of action of BCG in both domains appears to be intimately related. Therefore, we discussed tuberculosis (TB), the use of BCG in superficial bladder cancer, and potential applications of BCG to other cancers. It is well known that the incidence of TB in the United States showed a leveling off rather than the predicted continuous decrease beginning in 1986, largely due to the influence of HIV and/or AIDS on the incidence of active TB disease. However, if the situation is bad in the United States, it is much worse in Africa, where very alarming projections show the expected incidence of TB to be greater because of the different prevalence rates of HIV over the next 10 years. The Venn diagram shown in figure 1 puts the TB situation into perspective. Of the world's 5 billion people, one-third, or 1.7 billion, are infected with TB. Among those with primary TB infection, there is an annual incidence of 8 million cases, of whom 3 million will die. In 1994, it was estimated that 13 million people were infected with HIV, of whom 5 million also have primary TB. Those who are coinfected and who live long enough will develop active TB; each year, there are ~0.5 million HIV-infected people who develop active TB and also have AIDS (TB being an AIDSdefining event). Among HIV-infected people, the incidence of active TB is ~5% per year or 50% over an estimated 10-year life span, 25 times the incidence of TB among people not infected with HIV. To make the point of how timely this is, the local newspaper the other week contained an article describing 40 Canadian soldiers who had returned from the former Yu-