Production of staphylococcal enterotoxins A, B, and C was studied on the rice flour gel plate consisting of rice flour and distilled water devised by the authors simulating cooked rice that has commonly been incriminated for staphylococcal food poisoning in Japan. Enterotoxin produced on the rice flour gel plate was determined quantitatively by reversed passive hemagglutination. The rice flour gel plate supported production of fairly large quantities of enterotoxins A, B, and C. The rice flour concentration of the plate and the quantity of the surface water largely affected the enterotoxin production. The largest amount of enterotoxin, 0.2-0.4mg/25-ml plate, was produced in 3 days at 37 C on 16% rice flour gel plates overlaid with 4 to 8 ml of saline. It appeared that the production of enterotoxin A was more rapid than that of enterotoxin B or C.

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Laboratory-reared, Rickettsia tsutsugamushi-infected Leptotrombidium arenicola and L. fletcheri chiggers were fed on 1 and 2 human volunteers respectively. All subjects developed typical clinical signs and symptoms of scrub typhus beginning on days 8-10 post chigger attachment (PCA) ; these included fever, severe headache, myalgia, regional lymphadenopathy, and eschar. The two L. fletcheri subjects developed a transient generalized rash on days 3-4 after the onset of fever, and these two individuals also appeared to suffer a more severe clinical disease. Rickettsemias were detected in all three volunteers beginning on day 7 PCA, 1-3 days before the onset of clinical disease. Rises in indirect fluorescent antibody titers occurred starting on days 13-19 PCA (day 4-11 post fever) and in Weil-Felix OXK titers starting on days 16-22 PCA (days 7-14 post fever) . These results strongly suggest that the use of laboratory-reared chiggers is a reliable means of transmitting scrub typhus infections to volunteers.

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Serum immunoglobulin levels were measured with 144 domesticallybred cynomolgus monkeys, aged 0 day to 18 years. IgG level of the newborn just after birth was somewhat lower than that of their mother monkeys, continuing to decrease for 3 postnatal months. Thereafter, the level began to increase gradually till 4 to 5 years when an adult level was attained. IgA was detected on the day of birth in half of the animals and started to increase soon after birth, reaching an adult level in 5 to 6 years. A relatively low level of IgM was detected in all animals at birth. The increase of IgM level continued till 5 years of age. These patterns of immunoglobulin levels related to age are very similar to those of rhesus monkeys and human.

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The effect of lymphocytosis-promoting factor (LPF) on antibody response in mice was estimated under different sets of experimental conditions.
Four-and 6-week-old mice were intravenously inoculated with LPF. Three days later these mice were inoculated either intraperitoneally or intravenously with sheep red blood cell (SRBC) or human serum albumin (HSA) as an antigen.
The adjuvant effect of LPF was demonstrated on antibody response in 6-week old mice to intraperitoneally inoculated SRBC but not to intravenously-inoculated one. When 4-week-old mice were immunized, hemagglutinin production in response to intraperitoneally inoculated SRBC was not enhanced by LPF. In addition, a rather suppressive effect of LPF at a comparatively high dose was demonstrated on hemagglutinin production in response to intravenously inoculated SRBC.
Anti-HSA production was enhanced by inoculation of LPF in any combination of the mouse age and the route of antigen administration.
These findings indicate that the adjuvant effect of LPF on antibody response in mice depends upon experimental conditions: the age of mice, the quality of antigen and the route of antigen administration used for immunization.

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Electron microscopic survey of tuberculous lung lesions of mice revealed a novel type of lymphocyte-macrophage association. The finger-like projections with sharp or blunt tips of lymphocytes are formed as if pushing deeply the macrophage membrane to form pockets matching the shape of the projections. Intimate membrane contact occurs between these two cells, particularly at the leading edges. The biological significance of this morphological event remains to be a subject for future study.

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