Impact of the TCR Signal on Regulatory T Cell Homeostasis,Function, and Trafficking

Signaling through the T cell antigen receptor (TCR) is important for the homeostasis of naïve and memory CD4⁺ T cells. The significance of TCR signaling in regulatory T (Treg) cells has not been systematically addressed. Using an Ox40-cre allele that is prominently expressed in Treg cells, and a conditional null allele of the gene encoding p56^Lck, we have examined the importance of TCR signaling in Treg cells. Inactivation of p56^Lck resulted in abnormal Treg homeostasis characterized by impaired turnover, preferential redistribution to the lymph nodes, loss of suppressive function, and striking changes in gene expression. Abnormal Treg cell homeostasis and function did not reflect the involvement of p56^Lck in CD4 function because these effects were not observed when CD4 expression was inactivated by Ox40-cre.The results make clear multiple aspects of Treg cell homeostasis and phenotype that are dependent on a sustained capacity to signal through the TCR.     

Binding of human recombinant 125I-interferon gamma to receptors on human cells

Recombinant human interferon gamma (rIFN-gamma) produced in Escherichia coli was labeled with 125I to study its binding to receptors of HeLa and lymphoblastoid cells. All the cell lines examined had receptors for rIFN-gamma, although the binding varied considerably among different cell lines. The binding of 125I-rIFN-gamma was competed up to 90% by the addition of unlabeled rIFN-gamma, although not by the addition of IFN-alpha or -beta. By adding increasing concentrations of unlabeled rIFN-gamma to binding assays containing a constant amount of 125I-rIFN-gamma, we determined a KD of 3.7 and 6.3 X 10(-10) M for its binding to Daudi and HeLa cells, respectively. About 13,000 receptors per cell were present in Daudi and 5,000 in HeLa cells. The Mr of the IFN-gamma/receptor complex was determined by cross-linking experiments to be about 125,000. This complex is smaller than the IFN-alpha/receptor complex that has a Mr of about 140,000. The rIFN-gamma receptor was down-regulated when HeLa cells were treated with this interferon, but not when these cells were treated with IFN-beta. These findings suggest that the receptors for IFN-alpha and -gamma differ in several characteristics. The turnover of the rIFN-gamma receptor was measured by inhibiting protein synthesis with cycloheximide and the half-life of this receptor was found to be 2 h. The unglycosylated rIFN-gamma was bound to cellular receptors with an affinity similar to that previously reported for natural IFN-gamma. The lymphoblastoid cell lines examined had high affinity receptors for rIFN-gamma, but did not respond to treatment with this IFN with an induction of the synthesis of the enzyme (2'-5')oligo(A) synthetase, whereas HeLa cells responded to rIFN-gamma. The reason for the lack of response of lymphoblastoid cells is presently unknown.     

Delimitation of the maritime boundary in the gulf of Maine area

The compulsory dispute settlement regime included in the 1982 Law of the Sea Convention is recognized as one of the most comprehensive in a modern international convention. Yet, in the recent application of this regime, the question has arisen as to whether the procedural prerequisites associated with the LOS Convention's compulsory dispute settlement mechanism are so arduous as to avoid binding and compulsory jurisdiction in most instances. This article addresses that question by examining, in particular, the reasoning of the Southern Bluefin Tuna arbitration tribunal, which found Article 281 of Section 1 of the LOS Convention to bar jurisdiction to the compulsory dispute settlement mechanism prescribed by the Convention, and offers suggestions as to how states might distinguish or overcome the barriers imposed by the Southern Bluefin Tuna tribunal in future cases.     

Cutting edge: organogenesis of nasal-associated lymphoid tissue (NALT) occurs independently of lymphotoxin-alpha (LT alpha) and retinoic acid receptor-related orphan receptor-gamma, but the organization of NALT is LT alpha dependent.

Peyer's patch and nasal-associated lymphoid tissue (NALT) are mucosal lymphoid tissues that appear similar in structure and function. Surprisingly, we found that NALT, unlike Peyer's patch, was formed independently of lymphotoxin (LT)alpha. Furthermore, using mice deficient in the retinoic acid receptor-related orphan receptor-gamma, we found that NALT was formed in the absence of CD4+CD3- cells, which are thought to be the embryonic source of LTalpha. However, we also found that NALT of LTalpha-/- animals was disorganized and lymphopenic, suggesting that the organization and recruitment of lymphocytes within NALT remained dependent on LTalpha. Finally, we demonstrated that both the structure and function of NALT were restored in LTalpha-/- animals upon reconstitution with normal bone marrow. These results demonstrate that the organogenesis of NALT occurs through unique mechanisms.     

DETERMINATION OF GUSTATORY SUCROSE THRESHOLD IN WATER BY USE OF A LINEAR SUCROSE GRADIENT

A novel experimental method was developed which allows the determination of the threshold concentration of sucrose by use of a linear sucrose gradient in water. With this method a continuous tasting of the test-liquid is possible. A panel of 15 persons experienced in taste-testing was used. Three gradients of different steepness were applied: 0 to 1.5% (w/w) sucrose in 2 min (I), 3 min (II) and 4 min (III). The results of the new method were compared with those of the standard method (DIN). With gradients I and II we found values which were significantly higher than those of the standard method (I: 0.49% (w/w); II: 0.46% (w/w); DIN: 0.31% (w/w)), whereas with gradient III the same threshold value was found as with the DIN-Method (III: 0.32% (w/w)).