Adherence of Treponema pallidum subsp. pallidum in the rabbit placenta.

Congenital syphilis is the consequence of transplacental passage of Treponema pallidum. A system was developed to deliver virulent T. pallidum, Nichols strain, through an isolated uterine horn of a pregnant rabbit in order to investigate the mechanism by which T. pallidum is able to cross the placenta. While the pregnant rabbit was anesthetized, the ovarian artery and the uterine vein were cannulated and attached to a peristaltic pump. Treponema pallidum (2-5 x 10(8) in 10-15 ml RPMI-1640) were circulated via the peristaltic pump throughout the horn for 2 hr, after which the placentas were removed, fixed in formalin, and embedded in paraffin. This system was used to investigate treponemal binding to rabbit placenta at Day 20 and 26 during the gestation period of the rabbit (29-32 days). Examination of 5-microns Dieterle silver stained tissue sections revealed (i) a greater number of spirochetes in the later gestational stage placentas (Day 26) than in the earlier placentas (Day 20), (ii) organisms adhering to the trophoblastic tissue surrounding the maternal blood channels, and (iii) organisms appearing to be in the process of penetrating the trophoblastic tissue or that had completely penetrated from the channels into the trophoblastic elements. We suggest that T. pallidum may be adhering to placental components that are differentially expressed during gestation of the rabbit.

Syphilis and drugs of abuse.

In summary, treponemal infections in hamsters treated with THC were slightly enhanced in comparison with vehicle controls. A greater degree of enhancement was exhibited in rabbits; treponemes proliferated more readily during treatment with THC than in control animals. Contrary to expectations, this occurred even in lesions which were not developed fully, i.e., were not ulcerated. Thus, treponemes were present in aspirates earlier during infection and from sites which had received smaller inocula of treponemes in these rabbits than in controls. Lesions in control groups developed ulcerations earlier than did the THC-groups, but treponemes were too scarce to be seen in pre-ulcerative lesions in these animals. It appears that THC-treatment enhanced infection with T. pallidum. It may be that in the local skin lesion, macrophages which are vitally important in early host responses to treponemal infection may not have been functioning optimally and mediators of tissue damage may not have been produced and, therefore, ulceration was delayed in spite of enhanced infectivity of the treponemes.

Enhancement of hamster alveolar macrophage phagocytic activity by lymphokines.

Modulation of phagocytic activity of resident hamster pulmonary alveolar macrophages was accomplished by incubation of the cells in lymphokines prepared by stimulation of hamster splenocytes with concanavalin A or alloantigens in mixed lymphocyte cultures. Alveolar macrophages preincubated in either of these lymphokine preparations possessed significantly greater ability to ingest IgG or IgM plus complement-coated sheep erythrocytes, via their Fc or complement receptors, respectively, than macrophages exposed to control preparations. Ingestion of yeast particles also was enhanced with macrophages incubated in supernatants from cultures of stimulated splenocytes. Supernatant fluids from either mitogen- or alloantigen-stimulated splenocytes possessed migration inhibitory activity with characteristics similar to MIF from other animals; the phagocytosis-enhancing activity shared some of these characteristics.

Increased sensitivity of a new coagglutination test for rapid identification of Haemophilus influenzae type b.

A newly developed rapid coagglutination test for identifying Haemophilus influenzae type b organisms isolated from clinical specimens correlated 100% with the slide agglutination test but was 100- to 200-fold more sensitive.