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In three cases, two of which regarded exudative pericardium inflammation and one of lung abscess, biopsy revealed negative bacteriological results. Blood cultures resulted in culture of anaerobic Gram-negative bacteria from Propionibacterium genus. Precise chemo- geno-taxonomic studies were performed which confirmed generic identification of isolated strains. These were following: in cell wall--L-DAP, alanine, glycine, galactose, glucose, mannose; lack if mycolic acids; %GC 58-59. Basing on additional bacteriological studies it was established that two strains belong to the genus Propionibacterium acnes (type I), while third strain appeared to be Propionibacterium propionicum (before Arachnia propionica). These results confirm growing participation of relative pathogenic bacteria in opportunistic infections. It suggests necessity of blood cultures in cases subjected to prolonged therapy, especially when immunosuppression is involved.

Four groups of rabbits were given intravenously (i.v.) enriched T or B lymphocytes derived from normal or immunized donor rabbits; 24 hrs later, all these animals were infected intradermally (i.d.) with T. pallidum in order to check their immune status. Only rabbits which received immune T cells showed a state of resistance to infection with T. pallidum, whereas recipients of lymphocytes of three other groups did not.

Three groups of normal rabbits were administered: 1. viable lymphocytic cells; 2. lysates of lymphocytes obtained by freezing and thawing, and 3. low molecular weight dialyzable transfer factor (TF). The lymphocytes were derived from peripheral blood, lymph nodes, and spleens of rabbits: 1. cured of longlasting syphilitic infection by penicillin treatment, and 2. immunized with nonviable T. pallidum, exhibiting a good reactivity by tests for humoral and cell-mediated responses. All the three lymphocyte preparations were found to be able to transfer cell-mediated response as measured by the Macrophage Migration Inhibition Test (MMI) and the Skin Test for Delayed Hypersenitivity to Treponemal Antigens (SDH), from a reactive donor to the nonreactive recipient rabbit; the intensity of the response found in the recipient was roughly the same as in the donor. None of the lymphocyte preparations transferred humoral response, as measured by the TPI and VDRL tests. Only whole lymphocytic cells were found to be able to confer a stat of resistance to infection with T. pallidum on normal recipients.

The development of cell-mediated immunity was studied in rabbits: a) experimentally injected with T. pallidum, and b) artificially immunized with nonviable T. pallidum. The macrophage migration inhibition test (MMI test) using ultrasonicate of T. pallidum as antigen was employed to demonstrate this type of immunologic response. Lymphocytes of syphilitic rabbits were found to exert a pronounced inhibitory effect upon macrophage migration as early as one month after infection; between the fourth and sixth month, a transient decrease of this capacity occurred, followed by a slow but steady increase during the next two years, i.e. until the end of the observation period. In rabbits in which the infection had been controlled by penicillin treatment in the fifth month, no increase but gradual diminution of this capacity was observed. In the group of rabbits artificially immunized with nonviable T. pallidum, the MMI response appeared very shortly after commencement of the immunization and persisted for about nine months after completion of the immunization procedure. Only a crude correlation could be established between levels of the MMI response of the immunized animals and their resistance to infection with T. pallidum.

Experimental evidence has been obtained to show that the cell-mediated response in syphilis is protective. The use of chemical immunosuppressors (cyclophosphamide, 5-fluorouracil) resulted in the abolition of the cell-mediated response measured by the macrophage migration inhibition test (MMI test), and was accompanied by an enhancement in the severity of the lesions during the course of experimental syphilis in the rabbit. Successful adoptive transfer of resistance to syphilitic infection from immune donor rabbits to normal recipient rabbits employing lymph node lymphocytes was accomplished.

Two specific glycolipids identified as monomannosyl diglyceride (G1) and monoacylated glucose (G2), isolated from Nocardiopsis dassonvillei strains, were found to be biologically active. They elicited antibody response in rabbits when administered with some carrier components: lecithine, methylated bovine serum albumin (MBSA) and Freund incomplete adjuvant (FIA). Antibodies to the glycolipids were detected in antisera to G1 and in the sera against crude cell antigen of N. dassonvillei (N). The ability of the lipids to induceskin delayed hypersensitivity (SDH) as well as adjuvant and mitogenic effect were also studied. Generally glycolipid G1 seemed to be more active in antibody response whereas glycolipid G2 was a better stimulator of cellular response. Glycolipid G2 appeared to be distinct adjuvant and mitogenic factor.

The influence of various conditions of freezing in liquid nitrogen on the motility, virulence, antigens, and immunogenicity of Treponema pallidum was studied. The suspending medium, rate of freezing, kind and concentration of cryprotector, and duration of preincubation with cryoprotector were found to be critical. On the basis of the results obtained the optimal conditions of freezing of T. pallidum in liquid nitrogen were established. These are: the Nelson-Diesendruck medium with the addition of 10% DMSO; freezing rate 1 degree per min, and thawing rate between 12.6 degrees and 120 degrees per min.

Three groups of female rabbits were inoculated i.v. with T. pallidum. One group of the animals was treated with horse anti-rabbit thymocyte serum (ATS) one day before and during the next two weeks after infection. Two other groups, one treated with normal horse serum (NHS) in the same way as the previous one and the other untreated, served as controls. After various time intervals, all the animals were tested for the content of T and B lymphocytes in the peripheral blood, humoral (VDRL and TPI tests), and cell-mediated (SDH test) responses. Two days after testing, animals of each group were challenged i.d. with T. pallidum, and observed for appearance of syphilitic lesions. The treatment of syphilitic rabbits with ATS caused a significant reduction in the number of T lymphocytes and a distinct inhibition of development of cell-mediated immunity associated with the lack of resistance to reinfection with T. pallidum till the 16th week of the infection; the level of B lymphocytes and the development of serological responsiveness was not affected by ATS treatment. The results are interpreted as indicating the protective role of cell-mediated immunity in syphilis.

Rabbits infected intradermally with T. pallidum at four sites on the clipped back were treated with cyclophosphamide, 1 mg/kg body weight, twice before and every two days after inoculation for five months, or 5-fluorouracil 2.5 mg/kg body weight, according to the same regimen. Humoral response, as measured repeatedly by VDRL, FTA, and hemagglutination tests, was not affected by the application of the immunosuppressors. In contrast, the cell-mediated response, as determined by the Macrophage Migration Inhibition test was completely abolished in the treated rabbits. In the group of rabbits which were given immunosuppressors, syphilitic lesions appeared not only at the challenge sites, as usual, but also multiple multiform lesions developed over the entire dorsum after healing of the primary lesions. Taking into account the fact that abolishment of the cell-mediated response led to an aggravated course of the syphilitic infection, the results of these experiments were interpreted as indicating the protective role of the cell mediated response in syphilis.