George S. Douvas

Chlorpromazine: A Drug Potentially Useful for Treating Mycobacterial Infections

Chlorpromazine (CPZ) is one of several phenothiazines known to have antimicrobial properties. It can inhibit mycobacteria, and was reported in the early literature to improve tuberculosis clinically. CPZ was tested here for its ability to inhibit the replication of Mycobacterium tuberculosis and Mycobacterium avium in cultured normal human macrophages, as determined by counts of viable bacteria at 0, 4, and 7 days after bacterial infection of the macrophages. CPZ inhibited the intracellular bacteria at a concentration range of 0.23-3.6 micrograms/ml, and was more effective intracellularly than extracellularly. It was further tested for its ability to cooperate with isoniazid, streptomycin, pyrazinamide, rifampin, rifabutin, penicillin and ethambutol (EMB) against intramacrophage M. tuberculosis and M. avium. CPZ enhanced the effectiveness of most of the drugs tested against intracellular mycobacteria. However, the combination of CPZ and EMB did not result in augmented antimycobacterial activity.

Impaired neonatal natural killer-cell activity to herpes simplex virus: Decreased inhibition of viral replication and altered response to lymphokines

Human adult natural killer (NK) cells were recently demonstrated to inhibit herpes simplex virus (HSV) replicationin vitro. In this study we compared the ability of newborn and adult NK cells to inhibit HSV replication. Cord blood mononuclear cells (MNCs) from healthy, term newborns and MNCs from adults were analyzed for their percentage of Leu-11+ cells and comparedin vitro for their NK-cell activity against HSV-infected fibroblasts and the tumor cell line K562. Cord blood MNCs, compared with adult MNCs, had significantly lower percentages of Leu-11+ cells (5 vs 11%;P<0.01), less anti-K562 NK activity (6 vs 54 lytic units/107 cells;P<0.001), and less anti-HSV NK activity (5 vs 52% HSV plaque inhibition;P<0.02). Comparing individual neonates and adults with equal percentages of Leu-11+ cells, neonatal MNCs still had less NK activity against either target. When Leu-11+ MNCs were isolated using the fluorescence-activated cell sorter, neonatal Leu-11+ MNCs still inhibited HSV replication less than adult Leu-11+ MNCs (P<0.01). MNCs from some neonates had significant anti-K562 NK activity but poor anti-HSV NK activity, suggesting either nonidentical NK-cell subpopulations or specific suppression. Whereas neonatal NK activity against K562 was always augmented by prior exposure to either interferon (IFN) or interleukin-2 (IL-2), the neonatal NK activity against HSV-infected cells was only augmented for half of the neonates tested. Endogenous production of alpha-IFN and gamma-IFN by MNCs exposed to HSV-infected fibroblasts was the same for cells from neonates or from HSV-seronegative adults. More gamma-IFN was produced by MNCs from HSV-seropositive adults than from neonates or HSV-seronegative adults. These results suggest that although newborns have phenotypically identifiable NK cells and the capacity for IFN production, the ability of the NK cells to inhibit HSV replication is impaired, and their level of response and augmentation by specific lymphokines is target specific.

Mechanisms involved in the antibody-mediated suppression of tuberculin-type delayed hypersensitivity: II. The sensitivity of tolerance induction to cyclophosphamide pretreatment and splenectomy, and the demonstration of active suppression

Abstract The induction of tuberculin-type delayed hypersensitivity, as measured by skin test, can be specifically inhibited by administration of antibody during sensitization. The cellular mechanisms involved in this tolerance were investigated in CAP 1 mice, using chicken conalbumin as antigen. Tolerance was prevented when mice were treated with Cyclophosphamide 2 days before sensitization and suppression. However, it was not affected by splenectomy 7 or 21 days before sensitization. This tolerance could be transferred to normal CAF 1 mice with spleen cells, but not with thymocytes, when taken from donor mice 21 to 28 days after sensitization and tolerance induction. Production of these cells in the donors required both antibody and antigen. The cells responsible for the transfer were B cells, as shown by their sensitivity to rabbit anti-mouse-immunoglobulin serum and complement. In addition to B cells, serum from tolerant mice also could transfer suppression at 21 to 28 days. We conclude that sensitizing mice, and treating them with specific immunosuppressive antiserum, induces the recipients to make suppressor B cells and suppressive humoral factors, which are involved in arresting the induction of tuberculin-type delayed hypersensitivity.