A novel T cell-activating molecule (THAM) highly expressed on CD4-CD8- murine thymocytes.
Recent studies have focused on the potential role of accessory molecules such as CD2, CD28, Thy-1, or TAP in the delivery of activating signals to thymocytes through antigen-independent pathways. To better understand the molecular interactions involved in the expansion of early thymic immigrants, rat mAb were raised against murine thymocyte-surface molecules and screened for their capacity to trigger thymocyte proliferation. One of these mAb (H194-112, IgG2a) was found to recognize a novel heterodimeric thymocyte-activating molecule (THAM) of Mr = 110,000 to 128,000. Flow cytometric analyses and staining patterns on frozen thymus sections subdivided adult thymocytes in three subsets expressing THAM at either low (10%), moderate (80%), or high (5 to 8%) cell-surface density; these cell groups were found to correspond, respectively, to the medullary, the cortical, and the immature CD4-CD8-, J11d+ thymocytes, in which the T cell precursor pool is included. Moreover, most (90%) day 16 fetal thymocytes were also found to upregulate THAM cell-surface expression. The THAMhigh cells were localized in the subcapsular area of the neonatal thymus and scattered throughout the adult organ. Cross-linked mAb H194-112 induced the proliferation of both immature and mature thymocytes in the presence of either PMA or IL-1 and IL-2. The observation that early thymocytes up-regulate THAM along with the IL-2R suggests that this molecule might be involved in an important activation pathway during thymocyte differentiation.
Naquet
P
P
Centre d'Immunologie Institut National de la Santé et de la Recherche Médicale, Marseille, France.
MacDonald
H R
HR
Brekelmans
P
P
Barbet
J
J
Marchetto
S
S
Van Ewijk
W
W
Pierres
M
M
D000375:Aging; D000818:Animals; D000911:Antibodies, Monoclonal / Q000502:physiology; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis* / Q000276:immunology; D000939:Epitopes / Q000032:analysis; D007376:Interleukin-2 / Q000502:physiology; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D010641:Phenotype; D051381:Rats; D013601:T-Lymphocytes / Q000032:analysis* / Q000145:classification / Q000276:immunology; D013945:Thymoma / Q000032:analysis; D013950:Thymus Gland / Q000196:embryology / Q000254:growth & development; D000099192:CD69 Antigens
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D000939:Epitopes; D007376:Interleukin-2; D037181:Lectins, C-Type; D000099192:CD69 Antigens