Further evaluation and characterization of the mononuclear cell population of patients with prostate cancer

In a sequel to an earlier preliminary study, the distribution of mononuclear cell types found in the peripheral blood of an expanded population of patients with adenocarcinoma of the prostate was compared to an age-matched control group using monoclonal antibodies. Patients with localized disease (Stages A,B) had no or only subtle alterations in subset distribution compared to the control group, while those with advanced disease (Stages C,D) had significant alterations. Alterations in patients with advanced disease were characterized by decreases in T-cell (OKT3) and helper cells (OKT4) and increases in monocytes and null cells (OKM1) and B-cells. These alterations were further reflected in the T3/T4 and T3/T8 cell ratios. Monocytes also determined by non-specific esterase activity were increased in advanced disease. Alterations in the ratios between the various T-cell populations may ultimately provide useful adjunctive diagnostic/prognostic indicators for patient staging and treatment selection. Pending results of functional assays, the presently described alterations provide further evidence that increased mononuclear cells, particularly null cells, i.e., natural killer cells, in advanced vs. localized disease, may be an indication of the failure of the host's immune system to respond to an as yet encapsulated tumour as seen in patients with Stages A and B. As a possible explanation, the question of the privileged status of the prostate has been considered. Explanations for partial or complete immune privilegedness of the encapsulated prostate include: i) its anatomical location, i.e., absence of afferent lymphatics and ii) natural immunosuppressive secretory milieu, i.e., prostatic fluid and seminal plasma.