Studies on antigen-induced arthritis in mice. II. Immunologic correlates of arthritis susceptibility in mice.

Antigen-induced arthritis was developed in mice as a model of human rheumatoid arthritis by using methylated bovine serum albumin (mBSA) as antigen. It was found that most strains were susceptible, whereas CBA mice were resistant. We therefore investigated the humoral and cell-mediated immune responses to mBSA in resistant mice (CBA) and susceptible mice (exemplified by C57BL) to determine whether these were associated with susceptibility to arthritis. The resistant strain (CBA) differed from the suceptible strains in the following respects. First, there was a lower humoral immune response to mBSA as measured by passive hemagglutination, but this could be overcome by a larger immunogenic dose. Secondly, there were differences in response to low doses of DNP-mBSA after mBSA carrier preimmunization. Thirdly, there were striking differences in delayed-type hypersensitivity (DTH) to mBSA as determined by a radioisotopic assay in vivo; the response of CBA mice occurred early, at 5 days, declined quickly, and was weaker, whereas that of C57BL mice developed later and was long sustained. Genetic studies of the DTH response with hybrids and backcrosses showed an oligogenic control of immune responsiveness, with one gene being linked to the H-2b allele of the susceptible C57BL mice, and another being independent of the H-2 complex. Our findings indicate that in mice, susceptibility to antigen-induced arthritis with mBSA correlates with a higher responder state to this antigen, and that T cells are the major if not the only determinant of the high responder state.     

Behaviors of mice given forced-swimming.

Behaviors of mice in the forced swimming test are motionlessness, climbing and the other stereotypical behaviors. We observed these behaviors in different ages and sex and in repeated forced swimming trials. The findings were 1) quantities of the climbing and the other behaviors were different with the age and sex, 2) repeated per day forced swimming remarkably increased motionlessness and motionlessness is memorized for at least 14 days, and 3) climbing is the typical opposite behavior of motionlessness and was related to adrenergic but not serotonergic neuronal activity. When these behaviors are recognized as adaptation behaviors, we conclude that mice given repeated forced swimming, but not mice given one trial of forced swimming, can be considered as a model of human depression relating to adrenaline neuronal activity.     

Haemoglobin variants in mice.

Haemoglobin variants were studied in wild and laboratory house mice (Mus musculus), including standard and new inbred strains, using starch-gel electrophoretic technique. Single (Hbbs) or diffuse (Hbbd) types of haemoglobin were found in all of them. The embryonic haemoglobin pattern was different from although similar to that of the adult in all the strains. The haemoglobins revealed monomorphism in the inbred strains, while polymorphism was observed in non-inbred laboratory and wild mice.     

Spermatogenesis in Bclw-deficient mice.

Bclw is a death-protecting member of the Bcl2 family of apoptosis-regulating proteins. Mice that are mutant for Bclw display progressive and nearly complete testicular degeneration. We performed a morphometric evaluation of testicular histopathology in Bclw-deficient male mice between 9 days postnatal (p9) through 1 yr of age. Germ cell loss began by p22, with only few germ cells remaining beyond 7 mo of age. A complete block to elongated spermatid development at step 13 occurred during the first wave of spermatogenesis, whereas other types of germ cells were lost sporadically. Depletion of Sertoli cells commenced between p20 and p23 and continued until 1 yr of age, when few, if any, Sertoli cells remained. Mitochondria appeared to be swollen and the cytoplasm dense by electron microscopy, but degenerating Bclw-deficient Sertoli cells failed to display classical features of apoptosis, such as chromatin condensation and nuclear fragmentation. Macrophages entered seminiferous tubules and formed foreign-body giant cells that engulfed and phagocytosed the degenerated Sertoli cells. Leydig cell hyperplasia was evident between 3 and 5 mo of age. However, beginning at 7 mo of age, Leydig cells underwent apoptosis, with dead cells being phagocytosed by macrophages. The aforementioned cell losses culminated in a testis-containing vasculature, intertubular phagocytic cells, and peritubular cell "ghosts." An RNA in situ hybridization study indicates that Bclw is expressed in Sertoli cells in the adult mouse testis. Consequently, the diploid germ cell death may be an indirect effect of defective Sertoli cell function. Western analysis was used to confirm that Bclw is not expressed in spermatids; thus, loss of this cell type most likely results from defective Sertoli cell function. Because Bclw does not appear to be expressed in Leydig cells, loss of Leydig cells in Bclw-deficient mice may result from depletion of Sertoli cells. Bclw-deficient mice serve as a unique model to study homeostasis of cell populations in the testis.     

Morphine mydriasis in mice.

In mice, morphine produces dose-dependent mydriasis. The mydriatic effect does not depend upon the integrity of the sympathetic system, and interference with central catecholamines or serotonin also does not abolish the response. Ro 4-1284, a neurotransmitter depletor, causes miosis and inhibits completely the response to morphine. This effect may possibly be related to depletion of histamine, GABA, or other neurotransmitter.     

Experimental hypersplenism in mice.

The authors induced experimental hypersplenism in mice with repeated intraperitoneal injections of methylcellulose ("Tylosa", Messrs. Kabl). Detailed haematological tests of the peripheral blood, a cytomorphological examination of bone marrow and spleen from puncture material and histological tests of the bone marrow, spleen, lymph nodes, thymus, liver, kidneys and lung tissue of hypersplenic mice were carried out. Among the haematological results, apart from findings of marked erythrocyto-, leucocyto- and thrombocytopenia, attention is drawn to the finding, not previously described in the literature, of lowered osmotic resistance and elevated phagocytic activity of the leucocytes of hypersplenic mice.     

Genetic studies in NZB mice. II. Hyperdiploidy in the spleen of NZB mice and their hybrids.

The presence of hyperdiploidy was studied in New Zealand black (NZB) mice and the progeny of NZB X DBA/2 crosses and backcrosses. Hyperdiploidy was observed in the spleens of a majority of NZB mice but not in DBA/2 mice at 1 year of age. In crosses of NZB with the DBA/2 strain, hyperploidy was observed only in backcrosses to NZB. Hyperdiploidy appeared to be determined by a recessivley inherited trait and was not related to the presence of other immunological abnormalities, including splenomegaly, hypergammaglobulinemia, and spontaneous antibodies cytotoxic for T cells and reactive with single-stranded DNA. Abnormal cells were not present in Concanavalin A-stimulated 48-h spleen cultures. There was no difference in the in vitro sister chromatid exchange rate between the autoimmune NZB strain and the non-autoimmune DBA/2 strain. Identification of NZB chromosomes by banding analysis showed that chromosomes 15 and 17 were frequently present in more than two copies in hyperdiploid spleen cells. NZB chromsomes also had reduced C-banding in an autosomal pair. These studies indicate that chromosomal abnormalities which occur in NZB mice may be useful as genetic and cytogenetic markers.     

Immunity to sporozoite-induced malaria infeciton in mice. I. The effect of immunization of T and B cell-deficient mice.

The cellular basis of immunity to sporozoites was investigated by examing the effect of immunization of T and B cell-deficient C57BL/6N X BALB/c AnN F1 (BLCF1) mice compared to immunocompetent controls. Immunization of T cell-deficient (ATX-BM-ATS) BLCF1 mice with x-irradiated sporozoites did not result in the generation of protective immunity. The same immunization protocols protected all immunocompetent controls. In contrast, B cell-deficient (micron-suppressed) BLCF1 mice were protected by immunization in the majority of cases. The absence of detectable serum circumsporozoite precipitins or sporozoite neutralizing activity in the micron-suppressed mice that resisted a sporozoite challenge suggests a minor role for these humoral factors in protection. These data demonstrate a preeminent role for T cells in the induction of protective immunity in BLCF 1 mice against a P. berghei sporozoite infection.