RESUMO
The CD2 family is a growing family of Ig domain-containing cell surface proteins involved in lymphocyte activation. Here we describe the cloning and expression analysis of a novel member of this family, B lymphocyte activator macrophage expressed (BLAME). BLAME shares the structural features of the CD2 family containing an IgV and IgC2 domain and clusters with the other family members on chromosome 1q21. Quantitative PCR and Northern blot analysis show BLAME to be expressed in lymphoid tissue and, more specifically, in some populations of professional APCs, activated monocytes, and DCS: Retroviral forced expression of BLAME in hematopoietic cells of transplanted mice showed an increase in B1 cells in the peripheral blood, spleen, lymph nodes, and, most strikingly, in the peritoneal cavity. These cells do not express CD5 and are CD23(low)Mac1(low), characteristics of the B1b subset. BLAME may therefore play a role in B lineage commitment and/or modulation of signal through the B cell receptor.
Assuntos
Antígenos de Diferenciação de Linfócitos B/genética , Antígenos CD2 , Proteínas de Membrana/genética , Família Multigênica/imunologia , Homologia de Sequência de Aminoácidos , Sequência de Aminoácidos , Animais , Células Apresentadoras de Antígenos/imunologia , Células Apresentadoras de Antígenos/metabolismo , Antígenos de Diferenciação de Linfócitos B/biossíntese , Antígenos de Diferenciação de Linfócitos B/fisiologia , Transplante de Medula Óssea/imunologia , Antígenos CD2/genética , Células Cultivadas , Clonagem Molecular , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Humanos , Macrófagos/imunologia , Macrófagos/metabolismo , Proteínas de Membrana/biossíntese , Proteínas de Membrana/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Especificidade de Órgãos/genética , Especificidade de Órgãos/imunologia , Quimera por Radiação/imunologia , Retroviridae/genética , Família de Moléculas de Sinalização da Ativação Linfocitária , Transdução GenéticaRESUMO
The co-stimulatory B7 molecules (B7-1 and B7-2) are expressed on professional antigen-presenting cells in mice. In this study, we demonstrate that B7-1 (CD80) and B7-2 (CD86) are also expressed on murine T cells in the absence of major histocompatibility complex class II molecules. The temporal expression of these two molecules on T cells varies with the state of activation where resting T cells express B7-2 but show little or no expression of B7-1. Following activation, B7-2 expression is down-regulated and there is a concomitant increase in the expression of B7-1 on the cell surface which peaks at about 72 h. Thus these two co-stimulatory molecules are reciprocally expressed on the T cell surface. This pattern of expression of B7-1 and B7-2 on T cells suggests that these two molecules may have different roles in the generation and regulation of immune responses.