BACILLUS-CALMETTE-GUERIN POTENTIATES MONOCYTE RESPONSES TO LIPOPOLYSACCHARIDE-INDUCED TUMOR-NECROSIS-FACTOR AND INTERLEUKIN-1, BUT NOT INTERLEUKIN-6 IN BLADDER-CANCER PATIENTS

During the past decade, particular attention has been focused on treat ment of bladder cancer patients with the bacterial agent bacillus Calm ette-Guerin (BCG). In these studies, bladder cancer patients were inst illed with BCG (75 mg/50 ml) once per week for 6 weeks, 1-2 weeks foll owing trans-urethreal resection of the bladder. Cystoscopy was perform ed after 6 weeks and, unless tumor progression was present, monthly tr eatments were given for 1 year. Blood was drawn 2 h after the last ins tillation, and monocytes were isolated (5 x 10(6) cells/ml) and treate d, or not, with lipopolysaccharide (LPS) (20 mu g/ml) for tumor necros is factor alpha (TNF alpha), interleukin-1 alpha (IL-1 alpha) and inte rleukin-6 (IL-6) release. The levels of monokines were determined by a monokine-specific enzyme-linked immunosorbent assay. Our results clea rly show that, after 18 h incubation, macrophages from BCG-treated bla dder cancer patients produced from 2.8- to 1.9-fold and from 2.0- to 1 .3-fold greater amounts of TNF alpha and IL-1 alpha respectively, comp ared to macrophages from healthy controls, 5-fold higher than bladder cancer patients not treated with BCG. IL-6 was not affected. In anothe r set of experiments macrophages (5 x 10(6) cells/ml) from healthy sub jects were pretreated, or not, with BCG (100 mu g/ml) overnight and tr eated, or not, with LPS 20 mu g/ml alone and in combination with inter leukin-1 receptor antagonist (IL-1ra) 250 ng/ml. Macrophages treated w ith BCG had a strong stimulatory effect on IL-1 alpha release (9.45 ng /ml) while LPS was less effective (3.59 ng/ml). The combination of BCG plus LPS produced an additive effect on IL-1 alpha release (13.71 ng/ ml) compared to the effect of the compound alone. The addition of IL-1 ra (250 ng/ml) to BCG was not effective, while when IL-1ra was added t o BCG plus LPS only a partial inhibition of IL-1 alpha release was fou nd (9.83 ng/ml), compared to BCG plus LPS without IL-1ra (13.71 ng/ml) . These effects seem to be related to the inhibition of IL-1 alpha sti mulated with LPS, but not BCG. The priming effect of BCG exerted on LP S-stimulated monocyte production of TNF alpha and IL-1 alpha from blad der cancer patients led us to study the possible modulation of fibrino gen and C-reactive protein in the serum of BCG-treated cancer patients . The plasma levels of fibrinogen and C-reactive protein were higher ( approximately twice) in BCG-treated patients compared to values obtain ed in untreated patients or healthy controls. We conclude that the ben eficial immunotherapeutic effects of BCG in bladder cancer patients ar e related to its capacity to prime macrophages to enhance the release of TNF alpha and IL-1 alpha, but not IL-6 in response to physiological secondary stimuli, or through the direct stimulation of BCG on IL-1 a lpha or TNF alpha, which are directly involved in the killing of cance r cells. Moreover, the increase of IL-1 alpha or TNF alpha in BCG blad der cancer patients may lead to high plasma levels of fibrinogen and C -reactive protein, two proteins responsible for the acute-phase respon se.