Inhibition of functional T cell priming and contact hypersensitivity responses by treatment with anti-secondary lymphoid chemokine antibody during hapten sensitization

Recent studies have suggested a pivotal role for secondary lymphoid chemokine (SLC) in directing dendritic cell trafficking from peripheral to lymphoid tissues. As an extension of these studies, we examined the consequences of anti-SLC Ab treatment during Ag priming on T cell function in an inflammatory response. We used a model of T cell-mediated inflammation, contact hypersensitivity (CHS), where priming of the effector T cells is dependent upon epidermal dendritic cell, Langerhans cells, and migration from the hapten sensitization site in the skin to draining lymph nodes. A single injection of anti-SLC Ab given at the time of sensitization with FITC inhibited Langerhans cell migration into draining lymph nodes for at least 3 days. The CHS response to hapten challenge was inhibited by anti-SLC Ab treatment in a dose-dependent manner. Despite the inhibition of CHS, T cells producing IFN-gamma following in vitro stimulation with anti-CD3 mAb or with hapten-labeled cells were present in the skin-draining lymph nodes of mice treated with anti-SLC Ab during hapten sensitization. These T cells were unable, however, to passively transfer CHS to naive recipients. Animals treated with anti-SLC Ab during hapten sensitization were not tolerant to subsequent sensitization and challenge with the hapten. In addition, anti-SLC Ab did not inhibit CHS responses when given at the time of hapten challenge. These results indicate an important role for SLC during sensitization for CHS and suggest a strategy to circumvent functional T cell priming for inflammatory responses through administration of an Ab inhibiting dendritic cell trafficking.     

CD4+ T cells regulate CD8+ T cell-mediated cutaneous immune responses by restricting effector T cell development through a Fas ligand-dependent mechanism

The magnitude and duration of CD8(+) T cell-mediated responses in the skin to hapten sensitization and challenge, contact hypersensitivity (CHS), is negatively regulated by CD4(+) T cells through an unknown mechanism. In this study we show that CD4(+) T cells restrict the development and expansion of hapten-specific CD8(+) T cells mediating CHS responses to 2,4-dinitrofluorobenzene. In the absence of CD4(+) T cells, high numbers of hapten-specific CD8(+) T cells producing IFN-gamma were detected in the skin-draining lymph nodes on day 5 postsensitization, and these numbers decreased slightly, but were maintained through day 9, correlating with the increased magnitude and duration of CHS responses observed in these mice. In the presence of CD4(+) T cells, the number of hapten-specific CD8(+) T cells producing IFN-gamma detected on day 5 postsensitization was lower and quickly fell to background levels by day 7. The limited development of effector CD8(+) T cells was associated with decreased numbers of hapten-presenting dendritic cells in the lymphoid priming site. This form of immunoregulation was absent after sensitization of Fas ligand-defective gld mice. Transfer of wild-type CD4(+) T cells to gld mice restored the negative regulation of CD8(+) T cell priming and the immune response to hapten challenge in gld-recipient mice. These results indicate that CD4(+) T cells restrict hapten-specific CD8(+) T cell priming for CHS responses through a Fas ligand-dependent mechanism.     

IL-12 augments CD8+ T cell development for contact hypersensitivity responses and circumvents anti-CD154 antibody-mediated inhibition.

During sensitization with dinitrofluorobenzene for contact hypersensitivity (CHS) responses, hapten-specific CD8(+) T cells develop into IFN-gamma-producing cells, and CD4(+) T cells develop into IL-4/IL-5-producing cells. Administration of IL-12 during sensitization skews CD4(+) T cell development to IFN-gamma-producing cells, resulting in exaggerated CHS responses. In the current report we tested the role of IL-12 on CD8(+) T cell development during sensitization and elicitation of CHS to dinitrofluorobenzene. Administration of IL-12 during hapten sensitization induced the expression of IL-12Rbeta2 on both CD4(+) and CD8(+) T cells, augmented IFN-gamma production by these T cell populations, and increased the magnitude and duration of the CHS response to hapten challenge. CHS responses were virtually identical in wild-type and IL-12 p40(-/-) mice. Since engagement of CD40 on APC may stimulate IL-12 production, we also tested the role of CD40-CD154 interactions on the development of IFN-gamma-producing CD4(+) and CD8(+) T cells following hapten sensitization. Development of IFN-gamma-producing CD4(+) T cells during hapten sensitization was absent in wild-type mice treated with anti-CD154 mAb or in CD154(-/-) mice. In contrast, the absence of CD40-CD154 signaling had little or no impact on the development of IFN-gamma-producing CD8(+) T cells. These results demonstrate that the development of hapten-specific Th1 effector CD4(+) T cells in CHS requires both CD40-CD154 interactions and IL-12, whereas the development of IFN-gamma-producing effector CD8(+) T cells can occur independently of these pathways.     

Intraspecies structure of the pacific herring <Emphasis Type=Italic>Clupea pallasii</Emphasis> valenciennes, 1847 (Clupeidae: Clupeiformes) in the Sea of Japan and the southern Sea of Okhotsk inferred from the variability of mitochondrial DNA control

The differentiation of local herring populations from the Sea of Japan and the southern Sea of Okhotsk was assessed on the basis of mtDNA (mitochondrial DNA) control region variability. Three samplings of sea herring and one sampling of lake herring were studied. The genetic analysis showed a significant (P < 0.01) difference between lake and sea herring samplings and no differentiation among sea samplings (P > 0.05). AMOVA analysis revealed that only 4.11% of the variability was attributed to the interpopulation component, while variability within populations was 95.89%. It is suggested that the reason for the weak differentiation of local sea herring populations may be an intensive gene flow.     

Alloreactive T cell responses and acute rejection of single class II MHC-disparate heart allografts are under strict regulation by CD4+ CD25+ T cells

Skin but not vascularized cardiac allografts from B6.H-2bm12 mice are acutely rejected by C57BL/6 recipients in response to the single class II MHC disparity. The underlying mechanisms preventing acute rejection of B6.H-2bm12 heart allografts by C57BL/6 recipients were investigated. B6.H-2bm12 heart allografts induced low levels of alloreactive effector T cell priming in C57BL/6 recipients, and this priming was accompanied by low-level cellular infiltration into the allograft that quickly resolved. Recipients with long-term-surviving heart allografts were unable to reject B6.H-2bm12 skin allografts, suggesting potential down-regulatory mechanisms induced by the cardiac allografts. Depletion of CD25+ cells from C57BL/6 recipients resulted in 15-fold increases in alloreactive T cell priming and in acute rejection of B6.H-2bm12 heart grafts. Similarly, reconstitution of B6.Rag(-/-) recipients with wild-type C57BL/6 splenocytes resulted in acute rejection of B6.H-2bm12 heart grafts only if CD25+ cells were depleted. These results indicate that acute rejection of single class II MHC-disparate B6.H-2bm12 heart allografts by C57BL/6 recipients is inhibited by the emergence of CD25+ regulatory cells that restrict the clonal expansion of alloreactive T cells.     

Dynamics of biologically active enterotoxin release by E. coli]

Accumulation of E. coli enterotoxin in the Finkelshtein's culture medium in growing the cells in a 30-litre reactor was studied. Accumulation of active highly molecular enterotoxin occurred in the course of a 6-hour cultivation of E. coli, strain P-99 (O141: K85ab; K88ab: H4) in the fluid medium under aeration. Oxygen utilization, synthesis and release into the nutrient medium of pyruvic acid, and protein accumulation were observed. The preparation obtained was stable to the lyophylic drying, contained thermolabile and thermostable toxins and marked edema of mouse limbs. The data obtained were of significance for the industrial production of active enterotoxin preparations.     

Studies of pulsed and continuous microwave discharges used to deposit diamond films

Results are presented from optical measurements of the atomic hydrogen density and the gas temperature in a reactor for depositing diamond films from the plasmas of pulsed and continuous microwave discharges at a fixed mean microwave power. The results obtained make it possible to explain the fact that the growth rate of diamond films in the plasma of a pulsed microwave discharge is larger than that in a continuous microwave discharge.     

Kinetics of the processes of Streptococcus pneumoniae batch cultivation in relation to the physiological state of the inoculum

The present investigation, carried out with the use of S. pneumoniae as a model, has shown that the kinetics of cultivation processes depend on the preparation of the seed culture. The use of the seed culture, taken at the end of the exponential phase of growth, leads to high initial and maximum specific growth rates and a shorter lag phase, high productivity of the process and the economic coefficient of the yield of the biomass. If pH and pO2 are maintained at a set level, the most operative parameter of the process is the redox potential. A new informative characteristic of the cultivation process (T) is proposed. This characteristic permits the comparison of growth processes and indicates the time in which the fluctuations of Gibbs's free energy per 1000 million cells decrease to a definite level.