A series of mutations in mice was tested for splenic NK-cell activity against YAC-1 target cells. Mutations at six loci that reduce NK-cell activity in the homozygous state were identified, including ...beige (bg), hairless (hr), motheaten (me), obese (ob), steel (Sl) and, to lesser extent, dominant spotting (W). Motheaten mice displayed the most profound NK-cell deficiency, with NK-cell activity virtually absent. Two mutations, nude (nu) and lymphoproliferation (lpr), produced elevated NK-cell-mediated lysis. The double homozygous recessive nu/nu bg/bg nude-beige mouse was viable and NK-cell-deficient, with activity slightly higher than that of +/? bg/bg beige littermate controls. Pigmentation mutants related to beige, including pale ears (ep), pearl (pe) and ruby eyes (ru2J) did not dramatically influence NK-cell levels. Unlike the obese gene, other mutations leading to obesity, diabetes (db) and yellow (Ay), did not impair NK-cell function. The possible site of gene action of these mutations in the NK-cell pathway is discussed.
W/WV mice are severely deficient in mast cells. The absence of mast cells in skin and salivary glands was found to be paralleled by a drastic decrease of the histamine levels in these tissues when ...compared to non-anemic +/+ control mice. Brains of W/WV mice are also devoid of mast cells. A comparison of the histamine concentrations in several brain regions of W/WV mice and controls revealed a moderate decrease in cerebral cortex, thalamus, hypothalamus and midbrain but no change in pons, medulla and cerebellum. These findings provide strong evidence that mast cells contribute to the histamine content in forebrain regions but not in hindbrain regions. It is speculated that there may exist histaminergic neurons intrinsic to the medulla and pons.
Homozygosity for the severe combined immunodeficiency (scid) mutation results in a block in T- and B-lymphocyte development. An unusually high incidence of spontaneous thymic lymphoma development was ...observed after transfer of this mutation from the C.B-17 congenic strain background onto the diabetes-susceptible nonobese diabetic (NOD) background. Thymomagenesis in the NOD-scid/scid mouse was associated with expression of an NOD mouse-unique endogenous ecotropic murine leukemia provirus locus (Emv-30, mapped to proximal region of chromosome 11) not expressed in the standard substrain NOD/Lt thymus. All tumors exhibited insertions of ecotropic proviruses, whereas only a subset also exhibited proviral integrations of mink cell focus-forming retrovirus. Neither class of retrovirus was associated with consistent integration into genes previously associated with activation of oncogenesis. We propose that the unusual features of T-cell ontogeny characteristic of the NOD inbred strain synergize with the scid-imparted block in thymocyte development, leading to activation of the NOD-unique Emv-30 to initiate thymomagenesis.
The severe combined immunodeficiency (scid) mutation was backcrossed onto the C57BL/6J strain background in order to study the role of natural killer (NK) cells in rejection of normal and malignant ...human lymphohematopoietic cells. C57BL/6J-scid/scidmice showed severe loss of mature T and B cells accompanied by increased percentages of NK1.1+cells and myeloid cells. Although little or no serum immunoglobulin was detectable prior to 2 months of age, all mice tested had circulating immunoglobulin by 7.5 months of age. C57BL/6J-scid/scidmice had markedly elevated levels of both hemolytic complement activity and NK cell activity compared with C57BL/6J-+/+ controls. Weekly injections with anti-NK1.1 antibody resulted in elimination of NK cell activity in C57BL/6J-scid/scidmice throughout 8 weeks of treatment. Although human CEM-C7 T lymphoblastoid tumor cells grew slowly in unmanipulated C57BL/6J-scid/scidmice, anti-NK1.1 treatment resulted in increased growth accompanied by metastasis of human lymphoma cells to the brain, liver, and kidney. In contrast to T lymphoblastoid tumor cells, nonmalignant human peripheral blood mononuclear cells engrafted at low levels in anti-NK1.1-treated as well as in unmanipulated C57BL/6-scid/scidmice. Backcrossing of the beige (bgJ) mutation onto the C57BL/6-scid/scidgenetic stock caused decreased NK cell activity accompanied by granulocyte defects. C57BL/6-scid/scid bgJ/bgJmice showed metastasis of human CEM-C7 cells to the brain and other organs but supported only low levels of engraftment with human peripheral blood mononuclear cells. These results demonstrate that NK cells, in the absence of an adaptive immune system, function in resistance to metastasis of human lymphomas and suggest that innate immune factors in addition to NK cell function mediate resistance to engraftment of normal human peripheral blood leukocytes.
Epidermal growth factor (EGF) receptor binding properties were examined in spontaneous ovarian granulosa cell (GC) tumors from SWR and SWR-derived strains of mice. EGF binding was measured at room ...temperature in tissue homogenates from GC tumors and normal ovaries from adult randomly cycling mice. GC tumor tissue displayed significantly increased EGF binding and 2 receptor populations (R1 and R2). Normal ovarian tissue appeared to have only one receptor population with a dissociation constant (KD) similar to the R1 (high-affinity) receptor in GC tumors. In subsequent experiments, GC tumor and normal granulosa cells from immature mice were analyzed in primary cultures for EGF binding, immunofluorescence microscopy for receptors, and cell proliferation. After 24 hr in culture, the GC tumors bound 10-fold more EGF/micrograms protein than did normal granulosa cells. GC tumor cells, but not normal granulosa cells, showed specific immunofluorescence when reacted with a polyclonal antibody to mouse EGFR. During 96 hr in culture, GC tumor cells, but not normal cells, showed a significant proliferative response to EGF. In conclusion, the EGF binding capacity is markedly increased in GC tumor cells and the proliferation data suggest that this growth factor supports tumor growth in the SWR model system.
Adoptive immunotherapy, consisting of cyclophosphamide injection and the i.v. transfer of tumor-sensitized T cells, resulted in rejection of the immunogenic fibrosarcoma, MCA/76-9, by syngeneic ...C57BL/6J (B6) mice. The same treatment of tumor-bearing congenic immunodeficient mice, homozygous for the deleterious mutations nude (nu) and rhino (hrrh), did not result in tumor rejection. Paradoxically, the intratumor and intrasplenic changes taking place in each of the three strains after therapy were indistinguishable. There was an increase in Thy-1+, Ly-2+, or L3T4+ cells at the tumor site 8 days after adoptive immunotherapy and a similar increase in Thy-1+ cells in the spleen. Moreover, the T cells isolated from the tumors or spleens from each genotype were shown to be specifically cytotoxic in vitro as well as in an in vivo Winn assay. Further evidence that immune amplification had occurred in the immunological mutant mice was provided by experiments showing (a) the ability of spleen cells from tumor-bearers and those tested after therapy to produce IL-2 in response to Con A stimulation and (b) an increase in class II-MHC antigen expression by tumor-associated macrophages. The data suggest that, although amplification of antitumor immune responses occurred in the immunological mutants, the absence of a critical host factor limited the potency of the antitumor response.
Human lymphoematopoietic stem cells engraft in irradiated immunodeficient mice that are homozygous for the severe combined immunodeficiency (scid) mutation. Engraftment levels in C.B-17-scid/scid ...mice, however, have been low and transient, decreasing the utility of this model for investigation of the development potential and function of human stem cells. In the present study, we have used NOD/LtSz-scid/scid mice as recipients and human cord blood as a source of donor stem cells. Our results demonstrate that NOD/LtSz-scid/scid mice support approximately fivefold higher levels of human stem cell marrow engraftment than do C.B-17-scid/scid mice. Human CD34+ cells are present in the marrow of recipient mice, and the engrafted cells readily peripheralize to the circulation of the host. Terminal differentiation of the stem and progenitor cells into mature progeny is limited. Using a multiple-day injection protocol developed in mice, which allows engraftment of stem cells between congenic mice in the absence of irradiation preconditioning, we observed high levels of human cell engraftment in unirradiated NOD/LtSz-scid/scid recipients after three or five consecutive-day injections. These results demonstrate that NOD/LtSz-scid/scid mice support high levels of human stem cell engraftment and that xenogeneic lymphohematopoietic stem cells can engraft in unirradiated hosts without the need for ablative reconditioning. This model will be useful for the in vivo investigation of human stem cells and for the preclinical analysis of human stem cells for transplantation.
