Kenji Takeya

Three phases of phagocyte contribution to resistance against Listeria monocytogenes.

The contribution of phagocytes to protection against Listeria monocytogenes was analysed in outbred ddN mice. Most of the bacteria injected intravenously at a dose of 3 × 103 to 4 × 103 were trapped in the liver within 10 min. There was a transient 10-fold decrease in the number of bacteria by 6 h. Anti-listeria activity in the initial phase was resistant to X-irradiation but was inhibited by carrageenan, and was not influenced by immunization. The protection in this very early stage of infection seemed to be attributable to the function of fixed macrophages. Viable bacteria in the organs increased progressively but slowly from 6 h to 72 h to reach maximum numbers. Bacterial growth during this period was markedly enhanced by X-irradiation or treatment with carrageenan. Accumulation of free phagocytes seemed to suppress the bacterial growth in this phase. The number of bacteria began to decrease from day 4 and became undetectable by day 9. The suppressive effect on bacterial growth in this last phase may be dependent on immunologically activated macrophages and was reversed by X-irradiation and carrageenan. The course of local infection was similar to that of systemic infection except for the lack of initial decrease. We conclude that the course of infection with L. monocytogenes can be divided into three phases with regard to the roles of phagocytes in resistance.

Differing Contribution of Polymorphonuclear Cells and Macrophages to Protection of Mice against Listeria monocytogenes and Pseudomonas aeruginosa

Bacterial growth and lethality of Listeria monocytogenes in mice were augmented by carrageenan-treatment and X-irradiation (8 J kg-1), whereas growth and lethality of Pseudomonas aeruginosa were augmented by X-irradiation but not by carrageenan-treatment. Protection against L. monocytogenes, at least in the early phases, appears to depend mainly on macrophages, since carrageenan depletes macrophages but not polymorphonuclear cells (PMN), whereas protection against P. aeruginosa appears to depend mainly on PMN. Ineffectiveness of PMN in elimination of L. monocytogenes is supported by histological examination and observation of intracellular killing in vitro.

Cellular elements in the resistance to candida infection in mice. I. Contribution of T lymphocytes and phagocytes at various stages of infection.

Live organisms (cfu) of Candida albicans per organ were counted 1 hr and 1 to 20 days after an intravenous inoculation into various groups of mice which had distinct levels of immunologic or non‐immunologic defense mechanisms. a) The number of cfu in the liver decreased progressively in normal mice, but those in the kidney maintained a constant level during the observation period. b) The number of cfu in the liver decreased progressively also in nude mice. In their kidneys, however, cfu increased progressively at a late stage of infection. c) In lethally irradiated AKR or nude mice in which phagocyte functions were severely depressed, the number of cfu increased progressively in both liver and kidney from the initial stage of infection. d) In immunized AKR mice, growth of C. albicans was suppressed at late stages of infection. Such protective immunity could be transferred partly with immune lymphoid cells but not with hyperimmune serum in the experimental system employed. In protection against Candida infection, non‐immune phagocytosis and T cell‐mediated immunity appear to be required at the early and late stages of infection, respectively.

Depression of acquired resistance against herpes simplex virus infection in neonatally thymectomized mice

An increasing number of reports have been appearing on the depression of acquired immunity by neonatal thymectomy. Thymeetomy in mice soon after birth is associated with the impairment of such immunologic activities as to produce serum antibody, to develop delayed hypersensitivity and to reject homograft [reviewed by Miller et al. (1), and Good and Papermaster (2)]. We have studied the effect of neonatal thymectomy on the development of protective immunity in various viral and bacterial infections of mice (3, 4, 5, 6). Previous report has dealt with the increased susceptibility of neonatally thymectomized mice to herpes simplex infection (4). This paper describes the marked depression of acquired resistance against herpes simplex infection in neonatally thymectomized mice. A half of each littermates of colony-bred CF1 mice were thymectomized before 16 hours after birth. Remaining half of the littermates were either sham-thymectomized or left intact. The completeness of the operation was examined by autopsies at the end of each experiment. For the immunization strain 1019C] of herpes simplex virus (HSV) was used. This is an avirulent HSV which was kindly given by l~rof. K. Yoshino of Yokohama City University School of Medicine and has been maintained by passage in Vero cell cultures, an established strain derived from African green monkey kidney cells. One-tenth ml of strain 1019C1 of HSV having a titer of 105.5 TCIDs0/0.1 ml was inoculated intraperitoneally at 14, 17 and 20 days of age. Three days after the last

Cellular mechanisms in the protection against infection by Listeria monocytogenes in mice.

Listeria monocytogenes, in doses of 2-0 X 10(3) to 3-0 X 10(3) viable organisms, was injected into athymic nude mice, irradiated mice and mice treated with reticuloendothelial system-blocking agents. Viable counts on liver and spleen homogenates were made at intervals after infection. In both nude mice (nu/nu) and normal littermates (nu/+) of BALB/c background, the bacteria grew rapidly for 24 h but increased only slowly thereafter, to reach a plateau of about 10(5) per organ at 72 h. In nu/+ mice, the number of viable bacteria began to decrease after 6 to 9 days, with complete elimination by day 12. In nude mice, the number of Listeria remained at a stable level of approximately 10(5) per organ during the observation period of 21 days. In lethally irradiated nu/+ mice, bacteria grew progressively and extensively to reach 10(7) per spleen and 10(9) per liver by 72 h. Bacterial growth during the first 72 h was markedly enhanced by treatment with carbon particles, dextran sulphate 500 or silica. These enhancing effects were also observed in nude mice and in AKR, C3H/He and C57BL/6 animals. We conclude that both non-immune phagocytes and T cell-dependent mechanisms contribute to the resistance of mice to Listeria infection.

Importance of Antiserum and Phagocytic Cells in the Protection of Mice Against Infection by Klebsiella pneumoniae

Rabbit antiserum to Klebsiella pneumoniae showed a powerful protective effect against intramuscular infection in normal mice. No protective effect was observed in mice whose monocytes and polymorphonuclear cells were depleted by X-irradiation. The antiserum had approximately the same protective effect in mice whose macrophages were blocked selectively by carrageenan as in normal mice. It is concluded that antiserum exerted its effect by opsonic function and that opsonized K. pneumoniae were eliminated mainly by polymorphonuclear cells rather than macrophages, at least in an early phase of the infection. these findings were supported by histological examination and observation of intracellular killing in vitro.

Importance of Polymorphonuclear Leucocytes in Protection of Mice against Escherichia coli

Bacterial growth and lethality of Escherichia coli infection of mice were enhanced by X-irradiation but not by treatment with carrageenan. Since carrageenan depletes macrophages but not polymorphonuclear leucocytes, it is concluded that protection against E. coli, at least in the early phases, depends mainly on polymorphonuclear leucocytes.

The Synergistic Contribution of Macrophages and Antibody to Protection against Salmonella typhimurium during the Early Phase of Infection

The contribution of phagocytes and antibody to protection against Salmonella typhimurium during the early phase of infection in mice was analysed. Following intravenous injection, most of the bacteria were trapped in the liver and spleen within 10 to 60 min and killed within 6 h; surviving organisms began to multiply in these tissues after 24 h and reached a maximum at 5 to 7 d. The transient killing phase was abrogated by treatment with carrageenan, a macrophage blocker, but not by whole-body X-irradiation. These observations suggest that carrageenan-sensitive, but radio-resistant macrophages play an important role in the early phase of the infection. Actively immunized mice showed accelerated trapping and killing; the protection observed at the early stage of infection in immunized mice could be passively transferred to normal mice, whereas carrageenan-treated mice did not kill the bacterial even after receiving immune serum. It seems that the synergistic action of macrophages and antibody provided the main initial primary defence in immune animals.

Electron Microscopic Observations of Cell Division in Mycobacterium vaccae V1

Cell division of Mycobacterium vaccae was initiated by deposition of new wall material in the cross wall. The surface layers of the old wall remained continuous until septum formation was complete. Subsequently, rupture of the outer cell wall layers occurred circumferentially, leaving rings on the cell wall. The two daughter cells remained connected with each other at the new pole and bent to form V-shaped structures at the connecting point.

The role of the thymus in antibody production and in resistance to Japanese encephalitis virus infection.

Neonatally thymectomized mice and sham-operated mice were inoculated at various ages with various doses of either commercial vaccine or live Japanese encephalitis virus (JEV). Groups of neonatally thymectomized mice were found to have depressed capacity to produce circulating antibody as measured by hemagglutination inhibition test. Furthermore, it could be noted that the survival rate was high in groups in which the serum conversion rate was high, irrespective of the thymectomy at birth. From the results a humoral type of resistance against JEV infection was suggested as the basis for immunity.