Alymphoplasia (aly) mice, a natural strain with a mutant NF-κB-inducing kinase (NIK) gene, manifest a unique phenotype; they lack lymph nodes and Peyer’s patches, have a disturbed spleen architecture, and exhibit defects in both Ab and cellular immune responses. Although a stromal defect caused by impaired lymphotoxin-β receptor signaling accounts for their abnormal lymphoid organogenesis, the exact mechanisms underlying the development of immunodeficiency in aly mice are poorly understood. We therefore investigated the contribution of hemopoietic cells with the aly NIK mutation to the development of immunodeficiency. Transfer of aly/aly bone marrow cells into aly/+ mice resulted in poorly developed B cell follicles and lack of support for the development of germinal centers and isotype switching, indicating that the hemopoietic cells of aly mice contain an autonomous defect. However, follicular dendritic cell clusters were maintained in the spleens of these bone marrow chimeras, suggesting that the lack of follicular dendritic cell clusters in aly mice is probably due to the stromal defect. The aly mice lacked marginal zone B cells in their spleens, and aly/aly B cells showed an impaired proliferative response after in vitro stimulation. IL-2 production by activated T cells was also impaired. By contrast, the dendritic cells of aly mice exhibited grossly normal development and function. Supporting the concept of an autonomous cell defect, Rel protein expression was altered in aly/aly spleens. Thus, the aly NIK mutation affects hemopoietic cell function in an intrinsic fashion and, together with the stromal defect, may contribute to the development of immunodeficiency in aly mice.

We report the case of a 56-year-old Japanese woman with Behçet's disease and myelodysplastic syndrome (MDS), who had a history of episodic high-grade fever, recurrent oral and genital ulcers, and erythema nodosum, during a 13-year period from 1989 to 2002. Bone marrow aspirates obtained in January 1995 showed refractory anemia with trisomy 8, a subtype of MDS. Her serum levels of soluble interleukin-2 receptor (IL-2R), interferon-γ, IL-1β, IL-6, IL-8, and granulocyte-macrophage colony stimulating factor in the active state were higher than those in the inactive state, whereas those of tumor necrosis factor-α and IL-10 did not increase even in the active state. In this case, it was speculated that a T-cell immune response might have been involved in the disease pathogenesis, and that the repeated febrile episodes might have been a manifestation of neutrophil hyperfunction induced by increased serum levels of inflammatory cytokines.

The response of host cells L929 infected with causative agent of spotted fever group (SFG) rickettsiosis in Japan, the Katayama strain, was studied by electron microscopy. The rickettsiae penetrated the cytoplasm and multiplied here and after prolonged incubation progressed into the dilated cisternae of rough endoplasmic reticulum (rER), the perinuclear space, the deep invaginated nuclear membrane, and then the nucleoplasm of the host cells. The intranuclear rickettsiae showed different states: one type was enclosed by the double membrane of the host cell and the other type was free in the nucleoplasm. In addition to these double membrane‐bound and membrane‐free intranuclear rickettsiae, various membrane structures, including rER‐like structures, were also found in the nucleus. The cells infected with the rickettsiae underwent distinctive morphological alterations which occurred mainly within intracellular membranes of the host cells. These findings indicate the possibility that the intracellular membranes are characteristic cytopathological sites in rickettsia‐host cell interaction, and that these alterations may be related to a possible route of rickettsial penetration into the nucleus: passage through vesicles formed from invaginations in the nuclear membrane.

We report the case of a 73-year-old man with myelodysplastic syndrome (MDS) who developed Weber-Christian disease (WCD). Bone marrow aspirates showed refractory anemia with abnormal karyotypes such as trisomy 8, trisomy 8 and 14, and trisomy 8, 9, and 14. The patient had intermittent fever associated with multiple tender erythematous nodules on the skin. A biopsy sample taken from a nodule revealed focal subcutaneous infiltration of neutrophils and necrotizing fat tissue. We diagnosed the patient as having lobular panniculitis associated with myelodysplastic syndrome. The serum levels of soluble interleukin-2 (IL-2) receptor, interferon-Gamma, IL-1-Beta, IL-6 and tumor necrosis factor-Alpha were elevated in the active state but returned to normal after prednisolone therapy. This finding appears to implicate a T-cell immune response in the pathogenesis of Weber-Christian disease.