Spleen Natural Killer Research Articles

Toxoplasma-induced activities of peritoneal and spleen natural killer cells from beige mice against thymocytes and YAC-1 lymphoma targets.

Homozygous (bg/bg) and heterozygous (bg/+) beige mice were infected with Toxoplasma gondii, and splenic and peritoneal natural killer (NK) cell activities were assayed against YAC-1 lymphoma (NK-YAC) and thymocyte (NK-THY) targets. Although uninfected bg/bg mice were devoid of NK-YAC activity when compared with bg/+ mice, NK-THY activity was at a completely normal level. Both effector cells showed NK-1.2+ Thy-1.2 +/- asialo GM1+ asialo GM2+ phenotype. T. gondii infection induced a marked augmentation in splenic NK-YAC activity of bg/+ mice, whereas a slight increase was shown in the bg/bg mouse spleen cells. On the other hand, the infection did not change the splenic NK-THY activity of either strain of mice. An increased expression of Thy-1.2 antigen was shown on both NK-THY and NK-YAC effector cells from the infected mouse spleen. The T. gondii-induced augmentation was dramatic in the peritoneal cavity of the both mice. The activated peritoneal NK cells were of the NK-1.2- Thy-1.2+ asialo GM1 +/- asialo GM2+ phenotype and were considered to be generated from functionally inactive peritoneal cells. Splenic effector cells obtained from the infected mice were selectively depleted with target cell monolayer, whereas peritoneal cells from the infected mice were strongly absorbed by the target monolayers without selectivity. A weak but significant interferon (IFN) titer was detected in the peritoneum, but not in the spleen, of the infected mice. Most of the IFN titer was acid labile. Treatment with anti-IFN-alpha/beta resulted in partial decline of both NK and IFN activities of bg/bg mice, but not bg/+ mice. Thus, involvement of both IFN-alpha/beta and IFN-gamma in the generation of peritoneal NK cells and IFN-independent augmentation of splenic NK cells in toxoplasmosis were suggested.

Effect of L-alanosine on immune response.

L-alanosine is an antitumor compound which has recently entered clinical trials. Single i.p. doses of this drug inhibit antibody production to thymus-dependent and thymus-independent antigens as well as delayed hypersensitivity to SRBC in mice. Moreover, the in vitro lymphoproliferative responses of splenocytes to Concanavalin A and bacterial Lipopolysaccharides are also affected when the drug is added upon setting up the cultures. On the other hand, in vivo treatment with L-alanosine does not impair spleen natural killer (NK) activity. The results are discussed in an effort to characterize the immuno-suppressive activity of L-alanosine.

3-Methylcholanthrene: Transient Inhibition of the Lytic Step of Mouse Natural Killer Cells<xref ref-type="fn" rid="FN2">2</xref><xref ref-type="fn" rid="FN3">3</xref>

Female mice belonging to NMRI stock were inoculated neonatally with daily doses of 5 micrograms diethylstilbestrol (DES) or olive oil for the first 5 days after birth and in adult life with 20 or 100 micrograms 3-methylcholanthrene (MCA) or the vehicle tricaprylin only. The cytotoxic activity of spleen natural killer (NK) cells against YAC-1 target cells was studied in a 51Cr release assay at 2, 5, 10, or 15 days after the MCA injection. A dose of 20 micrograms MCA to neonatally olive oil-injected females did not influence the NK activity, whereas an injection of 100 micrograms MCA significantly depressed the NK activity to about half the value seen in controls. This suppression was transient, and the normal level was reached again 15 days after the injection. The depressed NK activity could not be related to humoral or cellular suppressor mechanisms. A study at the single-cell level revealed that the inhibition was due to interference with the lytic step of the NK cell without affecting target-binding capacity. In vitro exposure of spleen cells from MCA-treated animals to interferon fully restored the NK activity. Neonatal DES treatment resulted in a depressed NK activity in adult females to a level about half of that seen in olive oil-injected controls. The NK activity in DES-treated females was not influenced by either 20 or 100 micrograms MCA. The MCA-induced suppression of NK activity was discussed in relation to the earlier reported difference in incidence of MCA-induced sarcomas between DES-treated and control females after they were given 20 micrograms MCA in adult life, as well as in relation to the same incidence in the 2 groups treated with 100 micrograms MCA. The results are compatible with a significant role for NK cells during MCA carcinogenesis and indicate that a possible part of the tumorigenic effect of MCA is its early suppressive effect on NK cell activity.

Effect of amphotericin B on natural killer cell activity in vitro.

Incubation of murine peritoneal and spleen natural killer cells with amphotericin B at concentrations of 2.5, 5 and 10 mg/l in vitro, resulted in depression of their tumoricidal activity which had been augmented in vivo by infection with Toxoplasma gondii. In contrast, amphotericin B at the same concentrations had little or no effect on spontaneous natural killer cell activity in vitro. These in-vitro data suggest amphotericin B may have adverse effects on natural killer cell function in vivo.

Regulation of Natural Killer Activity in vivo

Spleen natural killer (NK) activity against YAC tumor cells was reduced in female C57BL/6J mice hypophysectomized at 3 weeks and sacrificed 4-8 weeks later. Proportions of null cells and of target binding cells in spleens from hypophysectomized and sham operated mice were significantly different. Administration of ovine growth hormone (GH) (100 microgram/day, i.p. for 10 days) resulted in a marked recovery of NK activity in hypophysectomized mice. NK activity by spleen cells from hypophysectomized or sham operated mice (with or without GH treatment) was mediated by non-T, non-B lymphocytes.

Quantitative studies of natural immunity to solid tumours in rats. NK activity in animals with primary or transplanted spontaneous tumours.

Natural killer (NK) cell activity was measured in a quantitative 6 h chromium release assay using sarcoma MC7 cells as targets. The total NK lytic activity present in the spleen and blood of tumour-bearing animals was compared with the corresponding values for age/sex/parity-matched animals. Rats with primary spontaneous tumours in the breast or subcutaneous sites showed normal levels of NK activity, while rats with primary spontaneous kidney tumours had elevated NK activity, the degree of augmentation being greater with increasing tumour size. A similar elevation of NK activity was generally found in animals with large, transplanted, spontaneous or chemically-induced tumours. This augmentation could only detected when total lytic activity was considered: when NK activity was measured merely on a cell-for-cell basis, it often appeared to be depressed in such animals, in agreement with previous reports. However, with one rapidly metastasizing spontaneous tumour, a real depression of both spleen and blood NK activity was found. Small inocula of cells from non-immunogenic spontaneous mammary tumours or from other non-immunogenic spontaneous tumours caused no early increase in systemic NK activity when injected into the mammary pad, a site where spontaneous tumours frequently arise. However, cells from one immunogenic spontaneous tumour and 2/3 immunogenic chemically-induced tumours did occasionally stimulate significant early increases in NK activity when placed at this site. Early changes in peritoneal exudate NK activity were also investigated using small inocula of these tumours injected intraperitoneally. Augmentation of NK activity occurred with a 3-fold greater frequency following inoculation with immunogenic tumour cells than with non-immunogenic cells in this system. It can be concluded from these studies that: (1) spontaneous tumours do not selectively arise in members of an inbred strain with subnormal NK activity; (2) most large tumours in rats stimulate rather than depress NK activity; (3) early boosting of NK activity by small inocula of tumour cells placed in the mammary pad does not occur with non-immunogenic spontaneous tumours; (4) early boosting of NK activity in the peritoneal site does occur with non-immunogenic tumours, but with a very low frequency. The latter findings suggest that developing spontaneous tumours are unlikely to stimulate the NK system, and emphasize the importance of using syngeneic, spontaneous tumours for studying tumour-host relationships in animals.

Effect of Chemotherapeutic Agents on Natural Cell-Mediated Cytotoxicity in Mice2

Spleen natural killer (NK) activity was investigated in cells from C57BL/6J mice treated with various chemotherapeutic agents; 51Cr-labeled YAC-1 lymphoma cells were used as targets. Treatment with azathioprine (a single injection of 100-400 mg/kg ip or 5 daily doses of 80 mg/kg lp) and cyclophosphamide (a single injection of 50--200 mg/kg ip or 5 daily doses of 25 mg/kg ip) resulted in a marked dose-dependent inhibition of NK activity 2 days later. NK cells recovered rapidly from drug-induced suppression; by 7 days after drug treatment, no difference from control values was observed. Dimethyltriazenoimidazole carboxamide (20--200 mg/kg ip) and adriamycin (10--15 mg/kg iv) did not impair natural cytotoxicity per unit number of lymphoid cells, daunomycin (10 mg/kg iv) caused borderline impairment of NK acitivity, and N-trifluoroacetyl-adriamycin-14-valerate (80 mg/kg iv) markedly suppressed natural cytotoxicity. These results are discussed in light of the known effects of these agents on T-cells, B-cells, and K-cells and on hematopoietic histocompatibility-type reactions.