Cutting edge: integration of human T lymphocyte cytoskeleton by the cytolinker plectin.

Chemokine-induced polarization of lymphocytes involves the rapid collapse of vimentin intermediate filaments (IFs) into an aggregate within the uropod. Little is known about the interactions of lymphocyte vimentin with other cytoskeletal elements. We demonstrate that human peripheral blood T lymphocytes express plectin, an IF-binding, cytoskeletal cross-linking protein. Plectin associates with a complex of structural proteins including vimentin, actin, fodrin, moesin, and lamin B in resting peripheral blood T lymphocytes. During chemokine-induced polarization, plectin redistributes to the uropod associated with vimentin and fodrin; their spatial distribution indicates that this vimentin-plectin-fodrin complex provides a continuous linkage from the nucleus (lamin B) to the cortical cytoskeleton. Overexpression of the plectin IF-binding domain in the T cell line Jurkat induces the perinuclear aggregation of vimentin IFs. Plectin is therefore likely to serve as an important organizer of the lymphocyte cytoskeleton and may regulate changes of lymphocyte cytoarchitecture during polarization and extravasation.

Rigidity of circulating lymphocytes is primarily conferred by vimentin intermediate filaments.

Lymphocytes need rigidity while in circulation, but must abruptly become deformable to undergo transmigration into tissue. Previously, the control of leukocyte deformability has been attributed to microfilaments or microtubules, but the present studies demonstrate the greater importance of vimentin intermediate filaments (IFs). In circulating T lymphocytes, IFs form a distinctive spherical cage that undergoes a rapid condensation into a juxtanuclear aggregate during chemokine-induced polarization. Measurements of the resistance of peripheral blood T lymphocytes to global deformation demonstrate that their rigidity is primarily dependent on intact vimentin filaments. Microtubules, in contrast, are not sufficient to maintain rigidity. Thus, vimentin IFs are a primary source of structural support in circulating human lymphocytes, and their regulated collapse is likely to be an essential element in chemokine-induced transendothelial migration.

Comparative sensitivity of four Anopheles (Diptera: Culicidae) to five repellents.

Five repellents were evaluated against Anopheles albimanus Wiedemann An. freeborni Aitken, An. gambiae Giles, and An. stephensi Liston, using a "free choice," dose-response testing procedure on rabbits. Overall, deet was the most effective repellent based on effective dosages (ED50's and ED95's), except against An. albimanus. An. albimanus was significantly more tolerant to deet compared with dimethyl phthalate or ethyl hexanediol. Permethrin was effective against all four anopheline species at the ED50 levels; however, the ED95 values were higher compared with the other repellents. There were significant differences in sensitivity of some of the four species to all the repellents tested, except dimethyl phthalate and indalone. The variability in the response of these anopheline species to repellents confirm that the extrapolation of repellent data from one anopheline species to another is unreliable and that comprehensive tests are needed for each species.

Socioeconomic impacts of school feeding programmes: empirical evidence from a South Indian village.

PIP: Tamil Nadu a poverty-stricken rural community in South India, funds a school feeding program with about 10% of the state budget. Comparisons of nutrition and literacy show that they are significantly related. No studies have yet been performed to analyse the effect of the feeding programs on aspects of a household's economic and social welfare. The feeding program in Tamil Nadu extends throughout the year, 7 days a week. It provides not only a reason for children to attend school, but also employment opportunities for those who wish to cook. 455 households were surveyed from 1 village using. A Gini coefficient of inequality to determine inequality levels of nutrition, food, and consumption expenditure. Sen's index of poverty was used to calculate the reduction in poverty levels. 3 household groups were defined: the agricultural labor, the silk weaver, and the cultivator. Linear program modelling utilized these 3 groups to study the total effect of nutrition on education. Linear regression was then used to determine the effect of the feeding program on participation in school. At the village level, a reduction of inequality in consumption and intake, an increase in energy intake, and a decrease in poverty level were found. In agricultural labor and silk weaver households, most of the money was spent on cereal food grains and children were mostly uneducated. If modelled to assume that children must be educated and are educated in schools providing food, results suggest that the increase in nutrition helps retain the children in the schools. Cultivator household response to the food programs was poor, since they usually have enough money to meet nutritional needs. Household income and school nutrition, but not adult literacy affect school participation. In general, nutrition offered in school caused a subsequent increase in household purchases of non-cereal items in the first 2 household types.^ieng

Antigen-specific protection against graft-vs-host induced immune deficiency.

A severe, antigen-nonspecific, and long-lasting immune-deficient state can be induced in healthy, adult immune-competent F1 hybrid mice by a single i.v. injection of parental T lymphocytes. The present report demonstrates that this graft-vs-host-induced immune deficiency (GVHID) can be prevented in an antigen-specific way by immunization of the F1 mice with allogeneic cells before induction of GVHID. Thus, spleen cells from (A X B)F1 mice primed with allogeneic cells from strain C and then injected with parental spleen cells from A did not generate cytotoxic T lymphocyte responses to trinitophenyl-modified self cells or to allogeneic cells from third party strains D or E. However, spleen cells from the same mice generated normal levels of cytotoxic T lymphocyte activity to allogeneic cells from C, the strain used for immunization. Furthermore, mice exposed to murine cytomegalovirus before induction of GVHID were resistant to a subsequent challenge with murine cytomegalovirus, whereas GVHID mice that received only the murine cytomegalovirus challenge all died. These findings are discussed with respect to the possibilities that primed and unprimed T helper cells may be differentially susceptible to the suppressive effects of GVH.