Changes in beta-adrenergic receptor distribution on immunocytes during differentiation: an analysis of T cells and macrophages.
The ability of cells of the immune system, immunocytes, to receive signals from the nervous as well as the endocrine system is dependent on the cells' expression of receptors for neurotransmitters and neurohormones. The number of receptors, especially beta adrenergic receptors (BARs), varies with the functional subset of immunocytes. However, little is known about how receptor number may vary during the life span (stem cell to mature activated immunocyte) of a given cell type. In this study, we have addressed this question by examining the affinities (Kd's) and the changes in receptor number (Bmax) on (1) clones of T cells and macrophages, (2) fresh thymocytes and splenocytes before and after activation with Concanavalin A (Con A) and phorbol myristate acetate (PMA)/Ca2+ ionophore (A23187), and (3) the cloned human monocyte U937 and the murine thymic lymphoma cell BW5147, in the presence and absence of PMA and A23187 ionophore. Drug treatments of fresh and cloned immunocytes alter the number but not the affinity of beta-receptors. Con A increases the number of beta-adrenergic receptors per cell, whereas PMA/ionophore decreases it. Similar decreases in BAR number are induced by PMA on cell lines BW5147 and U937. These data indicate that changes in receptor number can be regulated with different states of cell maturation and function. Thus, the immunological status of a given cell can influence the expression of BARs, thereby modulating its ability to respond to signals from the nervous and endocrine systems.
Radojcic
T
T
Department of Psychiatry, University of California, San Diego, School of Medicine, La Jolla.
Baird
S
S
Darko
D
D
Smith
D
D
Bulloch
K
K
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002454:Cell Differentiation; D002460:Cell Line; D003208:Concanavalin A / Q000494:pharmacology; D003348:Cortisone / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D011869:Radioligand Assay; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*; D015290:Second Messenger Systems / Q000187:drug effects; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D011943:Receptors, Adrenergic, beta; D003208:Concanavalin A; D000001:Calcimycin; D000242:Cyclic AMP; D013755:Tetradecanoylphorbol Acetate; D003348:Cortisone