Minako Araake

Comparison of Ciliostasis by Mycoplasmas in Mouse and Chicken Tracheal Organ Cultures

The cilia‐stopping effect of mycoplasmas of human and various animal origin in mouse and chicken tracheal organ cultures was studied. From the results in mouse tracheal organ cultures, the mycoplasma strains tested were divided into three groups: Mycoplasma pulmonis m53, M. pulmonis JB, M. pulmonis OK, M. mycoides subsp. mycoides PG1 and M. gallisepticum S6 showed a strong cilia‐stopping effect; M. pulmonis PG22, M. mycoides subsp. capri PG3, M. meleagridis 19729, M. neurolyticum Type A and M. arthritidis PG6 showed a mild effect; and M. pneumoniae FH, M. salivarium Hup, M. hominis type 1‐C and M. orale N‐C of human origin and Acholeplasma laidlawii PG8 showed a weak effect. On the other hand, in chicken tracheal organ cultures, only M. gallisepticum S6 showed a strong effect, M. meleagridis 19729 was affected to a lesser degree, and other mycoplasma strains showed a weak or no effect. The results indicate that some murine and poultry mycoplasmas showed a cilia‐stopping tendency in mouse and chicken tracheal organ cultures, respectively, while human mycoplasmas showed weak or little effect in both organ cultures. In mouse tracheal organ cultures, M. pulmonis m53 treated with heat, trypsin or formaldehyde, and the sterile filtrate of an m53 broth culture showed no cilia‐stopping effect. The relationship of the pathogenicity of mycoplasmas for their natural hosts to that for cultured respiratory cells is discussed.

High Affinity of Interaction between Superantigen and T Cell Receptor Vβ Molecules Induces a High Level and Prolonged Expansion of Superantigen-reactive CD4+ T Cells

In mice implanted with an osmotic pump filled with the superantigen (SAG) staphylococcal enterotoxin A (SEA), the Vβ3+CD4+ T cells exhibited a high level of expansion whereas the Vβ11+CD4+ T cells exhibited a mild level of expansion. In contrast, in mice implanted with an osmotic pump filled with SE-like type P (SElP, 78.1% homologous with SEA), the Vβ11+CD4+ T cells exhibited a high level of expansion while the Vβ3+CD4+ T cells exhibited a low level of expansion, suggesting that the level of the SAG-induced response is determined by the affinities between the TCR Vβ molecules and SAG. Analyses using several hybrids of SEA and SElP showed that residue 206 of SEA determines the response levels of Vβ3+CD4+ and Vβ11+CD4+ T cells both in vitro and in vivo. Analyses using the above-mentioned hybrids showed that the binding affinities between SEA and the Vβ3/Vβ11 β chains and between SEA-MHC class II-molecule complex and Vβ3+/Vβ11+ CD4+ T cells determines the response levels of the SAG-reactive T cells both in vitro and in vivo.

Immunological Responses of Hamsters in the Acquired Immune State to Mycoplasma pneumoniae Infection

Protective effects of vaccination of hamsters against Mycoplasma pneumoniae infection, evaluated according to the recovery of mycoplasmas and histopathological changes in the respiratory tract after challenge infection, persisted for at least 6 months after the final vaccination. Serum antibody levels reached a maximum in the second week after the last vaccination and decreased markedly between the first and the third months, but increased again in sera obtained from animals given booster injections. Metabolism‐inhibiting antibodies were detected in bronchial washings of animals showing high resistance obtained by vaccinal or passive immunization. Antiserum transfer was also effective for protection but cell‐mediated immune responses were not demonstrated in any animals up to 6 months after the vaccination. Even after 10 months, suppression of both mycoplasmal proliferation and lung lesions was apparent, and a single dose of the vaccine induced a significant booster effect. These findings suggest that (1) humoral immunity is more important than cell‐mediated immunity in resistance of hamsters to M. pneumoniae pneumonia, and (2) the antibody secreted in the respiratory tract may be involved in the local defense mechanisms.

Role of Humoral Antibodies in Resistance to Mycoplasma pneumoniae Pneumonia in Hamsters

Golden Syrian hamsters adoptively immunized with hyperimmune Mycoplasma pneumoniae rabbit antiserum, immunoglobulin (Ig) M‐rich (IgM) fraction, IgG‐rich (IgG) fraction, antiserum absorbed with either killed M. pneumoniae or killed Staphylococcus aureus organisms, or antiserum treated with 2‐mercaptoethanol (2‐ME) were examined for resistance against aerosol infection with virulent M. pneumoniae. Significant resistance to the establishment of infection in the respiratory tract was shown in hamsters pretreated with the untreated antiserum, IgG fraction or 2‐ME‐treated antiserum, whereas animals pretreated with the IgM fraction and the antisera absorbed with M. pneumoniae or S. aureus organisms were not significantly resistant. Histopathologically, lung lesions were markedly suppressed in animals with high resistance, but were typically pneumonic in animals with low or no resistance. The efficacy of adoptively administered serum preparations was closely related to their antibody titers. The results indicate that humoral antibody plays an important role in protection against experimental M. pneumoniae pneumonia in hamsters, although the participation of the cell‐mediated immune response was not determined.

Attachment of Mycoplasma pulmonis to Rat and Mouse Synovial Cells Cultured In Vitro

The attachment of Mycoplasma pulmonis m53 organisms to mouse and rat synovial cells was examined by using the organisms and the synovial cells treated in various ways. M. pulmonis treated with trypsin attached to the synovial cells, but the organisms treated with pronase, formaldehyde, glutaraldehyde, or heat did not. These findings suggest that the sites for binding M. pulmonis to the mouse and rat synovial cells are of polypeptide nature. Treatment of M. pulmonis with sialic acid and treatment of the synovial cell sheets with neuraminidase did not affect the attachment. The synovial cell surface for receptors M. pulmonis organisms would be different from those on respiratory cells or erythrocytes for M. pneumoniae or M. gallisepticum. Even nonviable organisms and M. pulmonis membranes attached to the mouse or rat synovial cells. The nature of the receptor of mouse synovial cells would be different from that of rat cells, since rat cells were affected by treatment with formaldehyde or glutaraldehyde, but mouse cells were not.

Relative Ability of Distinct Isotypes of Human Major Histocompatibility Complex Class II Molecules in Binding Staphylococcal Enterotoxin A

Relative ability of distinct isotypes of human major histocompatibility complex class II molecules to bind staphylococcal enterotoxin A (SEA) was investigated. SEA‐binding was observed in L cells transfected with DR2 and DQw1 genes. By contrast, it was not detected in L cells transfected with DPw4 and DP (Cp63) genes. All the transfectants supported SEA‐induced IL‐2 production by human T cells. Levels of the accessory activity were low in the DPw4 and DP (Cp63) transfectants compared with the DR2 and DQw1 transfectants. In view of the observation that all the transfectants express well the transfected gene products on their surface, the results indicate that DR and DQ molecules bind SEA with high affinity, while DP molecules bind it with fairly low affinity.

Immunogenicity and Protective Effect of Hemolysis Mutants of Mycoplasma pneumoniae

Two attenuated strains of Mycoplasma pneumoniae, P24‐S1 and P24‐S11, were tested for their ability as a live vaccine to confer on hamsters immune resistance against challenge infection with a virulent strain of M. pneumoniae, FH‐P24. Fifty percent protection was obtained by vaccination with the P24‐S1 strain administered once or twice. In contrast, only 10% of the animals were protected by the P24‐S11 vaccine even when it was given three times. Vaccination with the P24‐S1 strain resulted in higher humoral and cellular immune responses than the P24‐S11 did. These results suggest that the P24‐S1 strain has the primary qualities a vaccine which may be used for protection against human mycoplasmal infection.

Characterization and Pathogenicity of Hemolysis Mutants of Mycoplasma pneumoniae

Hemolysis mutants were produced by treating Mycoplasma pneumoniae FH‐P24 strain with N‐methyl‐N‐nitro‐nitrosoguanidine and were classified into three different groups. The first group of mutants, strains P24‐L1, L2, and L11, showed wide and clear hemolytic zones. Their attachment ability to erythrocytes of various animals and to hamster lung cells were the same as those of the parent strain. The second group, strain P24‐S1, showed non‐hemolysis and non‐hemadsorption, but retained the attachment ability to lung cells, although not to erythrocytes. The third group, strain P24‐S11, was non‐hemolytic, had completely lost the attaching ability, and did not proliferate in vivo. Strains in the first group produced significant microscopic pneumonic lesions in hamsters while strain P24‐S1 produced milder lung lesions. Strain P24‐S11 did not cause any lung lesions, and organisms were not recovered from the lungs of hamsters. The attachment of M. pneumoniae to respiratory epithelium as a cause of infection and the existence of a relationship between the hemolytic abilities of the organisms and histopathogenicity in the hamster lung tissue were further supported by the present data.

Mycoplasma pulmonis Arthritis in Congenitally Athymic (Nude) Mice--Histopathological Features

Histopathological examinations were performed on arthritic joints and other organs of strain BALB/cA nu/nu and nu/+ mice intravenously injected with Mycoplasma pulmonis strain m53. In both groups of mice suffering from polyarthritis, acute inflammatory lesions with infiltration of polymorphonuclear leukocytes in the synovia and periarticular tissues were observed one to two weeks after injection. In nu/nu mice, the acute inflammation appeared repeatedly up to 20 weeks after inoculation, when the experiment was terminated, and furthermore, extensive synovial and periarticular necrosis were characteristically present after the 4th week. Only a small number of lymphocytes and plasma cells were in the lesions. In nu/+ mice, after the early acute inflammation of arthritis, relapses of the infiltration of polymorphonuclear leukocytes were also observed in some mice in and after the 10th week. In addition, infiltration of lymphocytes and plasma cells was substantial after the 15th week. Focal necrosis was sometimes found in the liver of nu/nu mice. Perivascular infiltration of small lymphocytes and plasma cells was found in the lungs, liver and kidney of nu/+ mice in and after the 15th week. Repair mechanisms of injured articular tissues in nu/nu mice were histopathologically poor, while those in nu/+ mice seemed to be progressive and quite similar to those reported by many investigators for mice with the thymus intact. The histopathological differences are discussed in respect to the thymus‐dependent immune responses.