Use of Genetic Anaemias in Mice as Tools for Haematological Research

Experimental oral candidiasis in animal models

Oral candidiasis is as much the final outcome of the vulnerability of the host as of the virulence of the invading organism. We review here the extensive literature on animal experiments mainly appertaining to the host predisposing factors that initiate and perpetuate these infections. The monkey, rat, and mouse are the choice models for investigating oral candidiasis, but comparisons between the same or different models appear difficult, because of variables such as the study design, the number of animals used, their diet, the differences in Candida strains, and the duration of the studies. These variables notwithstanding, the following could be concluded. (i) The primate model is ideal for investigating Candida-associated denture stomatitis since both erythematous and pseudomembranous lesions have been produced in monkeys with prosthetic plates; they are, however, expensive and difficult to obtain and maintain. (ii) The rat model (both Sprague-Dawley and Wistar) is well proven for observing chronic oral candidal colonization and infection, due to the ease of breeding and handling and their ready availability. (iii) Mice are similar, but in addition there are well characterized variants simulating immunologic and genetic abnormalities (e.g., athymic, euthymic, murine-acquired immune deficiency syndrome, and severe combined immunodeficient models) and hence are used for short-term studies relating the host immune response and oral candidiasis. Nonetheless, an ideal, relatively inexpensive model representative of the human oral environment in ecological and microbiological terms is yet to be described. Until such a model is developed, researchers should pay attention to standardization of the experimental protocols described here to obtain broadly comparable and meaningful data.

Structure and regulation of the erythroid system at the level of progenitor cells

Considerable ground has been covered since the first clonal assays for hemopoietic cells were described. The possibility of studying populations of progenitor cells and the regulatory factors that influence them has already thrown considerable light on our understanding of the structure and physiology of the normal erythroid system and its alterations in disease. The relative importance of humoral and short-range factors and of possible cell-to-cell interactions in the regulation of proliferation and differentiation in the erythroid cell lineage is now being studied actively in several laboratories. The possibility of analyzing possible regulatory networks involving such highly reactive cells as lymphocytes and monocytes-macrophages in defined in vitro conditions now exists. As these studies are being extended to the diseased state, concepts related to alterations in regulatory mechanisms in syndromes with abnormal cell proliferation can be tested. Clinical applications in the treatment of patients with hematological disease are being contemplated. The usefulness of Epo for the treatment of the anemia of renal disease has been demonstrated already.

Characterization of murine hepatoma BW7756. III. Hematological profile of a tumor-associated anemia

A severe anemia develops in recipient C57L/J mice after syngeneic transplantation of the BW7756 murine hepatoma. The tumor undergoes an exponential growth spurt in the 14-21 days post-implantation, accompanied by a parallel increase in serum alpha-fetoprotein levels and a significant decrease of hemoglobin concentration and hematocrit extending to the 28th day. Concomitant with the decreased hematocrit, the blood volume displayed a 10% increase. The blood cell population was generally one of reticulocytosis and leukocytosis. Mild icteric plasma was observed and both "cold" and "warm" antibodies were detected in the sera of tumor-bearing mice. An elevation of IgM was observed by day 7, followed by a depletion of IgG1 and IgG2 throughout the tumor growth period. When RBCs of tumor-bearing mice were compared to those of normal mice, the same degree of osmotic fragility was found. However, the lifespan of the transfused RBC was shorter in tumor-bearing mice than in normal mice (half-life: 2 days vs. 4 days). The data suggest a type of auto-immune hemolytic anemia which is analogous to various hematopoietic disturbances described for murine hosts bearing solid tumors distal to hematopoietic sites.

Regulators of stem cell proliferation in the haemopoietic tissues of W/Wv and S1/S1d mice

The presence of CFU-S proliferation stimulatory and inhibitory activities in the bone marrow and spleens of normal mice (+/+) and mice with mutations affecting the proliferative behaviour of stem cells (S1/S1d and W/Wv) has been investigated. S1/S1d and +/+ bone marrow and spleen contain virtually no detectable stimulator but the corresponding tissues from W/Wv mice are both strongly stimulatory. S1/S1d marrow in particular, but also +/+ marrow are strongly inhibitory whilst +/+ spleen, S1/S1d spleen, W/Wv marrow and W/Wv spleen all contain inhibitory activity but at a lower specific activity. The data are compatible with studies of cell and tissue grafts that have indicated an intrinsic haemopoietic stem cell defect in W/Wv mice and an extrinsic, microenvironmental defect in S1/S1d mice. It is suggested that they are also compatible with defective regulatory interactions between stem cells and regulator-producing cells and that the W and S1 loci may code for products involved in the production of, or response to, CFU-S proliferation regulators.

Experimental oral infection with the yeast Candida albicans in mice with or without inherited iron-deficiency anaemia (sla)

The role of iron deficiency in the development of oral candidosis was investigated using the mouse mutant sex-linked anaemia (sla). Susceptibility was assessed in terms of the recovery of organisms, particularly from oral swabs, and histological evidence of infection approximately 10 days after the last exposure to Candida albicans. The influence of three factors was studied in mixed groups of normal and anaemic mice: mode of inoculation, treatment with tetracycline and treatment with hydrocortisone. The most susceptible group had received drinking water containing tetracycline (1 mg/ml), hydrocortisone (0.1 mg/ml) and candida (5 X 10(4) c.f.u./ml for 6 days). Anaemic mice showed a rather higher rate of recovery of organisms and more frequent histological evidence of infection than normal mice in certain groups. Neither of these tendencies was statistically significant alone but, taken together, they suggest that some small difference of susceptibility may exist between normal mice and mice with sla. The mouse model could be of value in studying the influence of several other inherited disorders on susceptibility to candidosis.