Immune responses in Mycoplasma pneumoniae infection of infant mouse and of man.

Infant mice (2 to 4 days old) were exposed to living Mycoplasma pneumoniae. The organisms were isolated in the order of 10(3) to 10(4) colony-forming units from the lungs of mice for 2 weeks after infection. Mononuclear cell infiltration was present in the lungs of infected mice. The specific IgG antibodies to membrane proteins of M. pneumoniae in the sera of infected mice were detected by enzyme-linked immunosorbent assay for about 800 days. In immunoblotting analysis, a 160-kilodalton (kDa) protein strongly reacted with the infected mouse sera. The dams immunized with membrane proteins conferred passive immunity on their offspring via colostrum. Specific IgG antibody appeared in the serum of infant mice that were given mouse anti-M. pneumoniae serum or convalescent human patient serum orally. These mice were also protected from challenge with M. pneumoniae. The immunoblotting patterns of patient sera were similar to those of infected mouse sera. The infant mouse model may be useful to investigate the host immune responses to M. pneumoniae.

Protective effect of colostrum in Mycoplasma pneumoniae infection induced in infant mice.

The immunological responses and mechanism of maternal immunity in Mycoplasma pneumoniae infection of mice were investigated. ICR female mice, 4 weeks old, and infant mice, 2 to 4 days old, were infected with M. pneumoniae. Anti-M. pneumoniae antibodies in serum and colostrum were determined by enzyme-linked immunosorbent assay. The specific IgG antibody production persisted for 9 months or longer in both the young and infant mice. These infected mice were protected from rechallenge with M. pneumoniae. In addition, the infected dams conferred passive immunity on their offspring. The infant mice born to uninfected normal dams were protected from the challenge with M. pneumoniae when fed by infected foster dams. Conversely, the infant mice born to infected dams were not protected from the challenge with M. pneumoniae when the infants were fed by uninfected dams. The specific IgG antibody appeared in serum of infant mice inoculated orally with M. pneumoniae-infected mouse serum and the infants were protected from challenge with M. pneumoniae, while the infants given protein A-absorbed serum were not protected from the challenge. These results suggest that one of the factors involved in the resistance of infant mice to M. pneumoniae infection is the specific IgG antibody present in the colostrum rather than the result of transplacental transfer.

Clinical complications of Mycoplasma pneumoniae disease--central nervous system.

The mechanism of the neurologic complications associated with primary atypical pneumonia is unknown. To examine the ability of Mycoplasma pneumoniae to enter the brain of experimental animals, the organism was inoculated into adult and suckling mice by various routes. After intranasal infection, M. pneumoniae was isolated from brains and lungs of both groups of mice. After intracerebral inoculation, the high levels of the mycoplasma persisted for two months or more in the brains of suckling mice. In addition, after intravenous infection, the systemic spread of infection occurred in the mice treated with high doses of cyclophosphamide. Our results suggest that M. pneumoniae may be able to reach the brain via blood and it may occur with relative ease in compromised hosts.

[Studies on the absorption and excretion of doxycycline for intravenous use (author's transl)].

The absorption and excretion of a new doxycycline solution for intravenous use (DOTC iv) were studied with the following results. 1. Serum levels following one shot intravenous injection of DOTC iv in glucose solution showed a good dose-response comparable with that of the same dose injection of pyrrolidinomethyltetracycline (PRM-TC). The urinary excretion was also examined. In 200 mg injection, nausea, general warm feeling, odor in mouth and tongue numbness were complained. 2. When DOTC iv was injected intramuscularly, the serum level did not reach the peak value and low level continued for a long time. Moderate local pain was complained at the site of injection. 3. The serum level following drip infection of DOTC dry fill showed a dose-response as well. The local vein tolerated well. 4. No abnormalities were found in clinical and laboratory examinations in all volunteers.