The role of mast cells in active and passive anaphylactic shock was examined using the WBB6F1 mouse, a genetically mast cell-deficient strain. Lethal anaphylactic shock occurred at high incidence rates in mice actively sensitized to bovine serum albumin (BSA). The reaction was specific to BSA since the shock could not be elicited by human or guinea pig serum albumin in these animals. Lethal shock could be prevented by CV-3988 but not by cyproheptadine, which suggests that the shock is mediated by PAF but not by histamine and serotonin. Similarly, lethal shock was provoked by homologous antigens in mice which had been passively sensitized with allogeneic anti-benzylpenicilloyl (BPO) IgG1 monoclonal antibody or with allogeneic or xenogeneic anti-BSA antiserum, but not in those sensitized with allogeneic anti-BPO IgE monoclonal antibody. These findings suggest that mast cells are not necessarily required for anaphylactic shock in the mouse.

These results suggest that ZnO appears to have an adjuvant effect on the immune system, especially Th2 but not Th1 immune responses.

We investigated whether recombinant human erythropoietin (rhEPO) therapy affected the lymphocyte subsets in patients on long-term maintenance hemodialysis (HD) with severe anemia. Before treatment, the numbers of peripheral blood lymphocyte, CD3+, CD4+, CD8+, and CD20+ cells were decreased in HD patients compared to those in healthy subjects, while the number of CD3+HLA-DR+ cells was increased in HD patients compared to that in healthy subjects. Furthermore, the number of CD4+CD45RA+ (naive T) cells was markedly decreased in HD patients (112 +/- 77 vs 241 +/- 146/microliters; P < 0.01). The number of CD8+S6F1+ (cytotoxic T) cells in HD patients was also less than that in healthy subjects (247 +/- 104 vs 122 +/- 83/microliters; NS). During a 6-month period of rhEPO therapy, we found that the low level of CD4+CD45RA+ cells gradually increased (from 112 +/- 18 to 163 +/- 24/microliters; P < 0.01) with the elevation of hematocrit values (from 21.5 +/- 1.7 to 28.2 +/- 3.5%; P < 0.05). The number of CD3+HLA-DR+ cells decreased after 1 month of rhEPO therapy (from 93 +/- 14 to 46 +/- 13/microliters) and gradually declined throughout the 6-month study period. In our in vitro study, we demonstrated that no effects were observed on [3H]thymidine uptake in the T cell subsets at various concentrations of rhEPO. These results suggest that rhEPO-induced immunoregulation is mediated by an indirect stimulatory effect on the immune system, this stimulation being accompanied by an improvement in physical condition.

Spontaneous development of dermatitis in DS-Nh mice under specific pathogenfree conditions was examined to verify the hypothesis [Exp. Anim. 46: 225-229, 1997] that Stapylococcus aureus (S. aureus) infection is causally associated with the dermatitis. Observation of the mice up to 28 weeks of age indicated that obvious dermatitis does occur under S. aureus-free conditions, though the incidence was low (six of 42 females and two of 90 males). Skin lesions in the absence of this bacterium showed histological changes very similar to those that can be observed under conventional conditions. In addition, hyperproduction of serum IgE was demonstrated in the dermatitis-positive mouse. These findings suggested that the dermatitis is triggered by IgE-mediated allergic reactions. Key words: dermatitis, DS-Nh mouse, Stapylococcus aureusThe DS-Nh (DS Non-hair) mouse [1] is a spontaneous hairless mutant of the DS mouse [7] that has been established as an inbred strain from a closed colony of dd mice at Aburahi Laboratories, Shionogi & Co., Ltd. According to the report by Haraguchi et al. [1], spontaneous development of chronic dermatitis under conventional conditions is characteristic of the DS-Nh strain regardless of age or gender. Although the pathogenic mechanism of dermatitis is unclear at present, the authors proposed a hypothesis that Stapylococcus aureus (S. aureus) infection is causally associated with dermatitis, based on their findings that S. aureus was isolated from the skin lesion and that experimental infection with the isolates promoted onset of dermatitis. They also described as further evidence that no dermatitis (Received 17 April 2002 / Accepted 18 September 2002 Address corresponding: T. Hirasawa, Aburahi Laboratories, Shionogi & Co., Ltd., Gotanda 1405, Koka, Shiga 520-3423, Japan was observed under specific pathogen-free (SPF) conditions. However, the test was performed in a vinyl isolator for a short time (until the mice were 16 weeks of age) using only five animals in their study [1]. In addition, we have observed that a few DS-Nh mice developed dermatitis after 50 weeks of age under SPF conditions (unpublished data). Since the presence or absence of the dermatitis under SPF conditions is a critical point for evaluating the role of S. aureus, careful re-examination using an adequate number of mice appeared to be necessary.The present study demonstrated that dermatitis develops in this strain even under S. aureus-free conditions, though at a much lower incidence than that under conventional conditions.