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Lymphocyte lineage commitment: instruction versus selection

Article Abstract:

Lymphocytes develop from hematopoietic stem cells. The precise mechanism by which hematopoietic stem cells produce T and B lymphocytes is unknown. The instructive model proposes that specific binding of the alphabeta T cell receptors to class I thymic MHC molecules produces a signal intructing the stem cell to develop into a CD8+ killer lineage while binding to a class II thymic MHC produces another signal to instruct the stem cell to develop into a CD4+ helper lineage. The stochastic/selective model, on the other hand, does not recognize receptor specificity.

Analysis, Lymphocyte transformation

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Cell adhesion: the molecular basis of tissue architecture and morphogenesis

Article Abstract:

Cell adhesion is required for the maintenance of the three-dimensional tissues of animals. It involves several complex mechanisms and requires cooperation from signaling events in the cell. Three general classes of proteins participate in cell adhesion: the adhesion molecules and adhesion receptors; the extracellular matrix; and, the cytoplasmic plaque or peripheral membrane proteins. Stable adhesion elements are required to ensure stable cell-cell contacts and to transduce signals effectively from one cell to another.

Genetic aspects, Molecular biology, Cell interaction, Cell interactions, Cell adhesion

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Alpha-4 integrins mediate lymphocyte attachment and rolling under physiologic flow

Article Abstract:

Experimental studies demonstrate that alpha-4 integrins activate lymphocyte contact and that alpha-4 beta-7 functions as a mediator of the ligation of blood-borne lymphocytes to lamina propria venules. Scanning electron microscopy indicates the abundant levels of alpha-4 beta-7 in the microvillous sites of cellular contact and the absence of beta-2 integrin LFA-1 in the villi. Alpha-4-, but not beta-2, integrins mediate leukocyte adhesion.

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