RESUMO
According to Jerne's network hypothesis, the unique amino acid sequences of Ig variable regions, that is, the idiotypic determinants can function in immunoregulatory mechanisms and cellular interactions. Indeed, Id-specific T-cells (mostly CD4+) have since been described, but the nature of Id-positive Ig on B-cells involved in recruiting T-cells is unclear. Studies from our ongoing investigation presented here clearly show that Id can evoke both CD4+ and CD8+ T cells, and exist not only as the integral components of a bona fide antigen-binding receptor Ig but also as distinct molecular entities in processed forms on the cell surface of B-lymphocytes. Using a B-cell hybridoma, 2C3, that expresses anti-hapten (phthalate) antibody receptors on the cell surface, we induced both Id-specific CD4+ and CD8+ T effector cells. The CD4+ T cells were suppressive and mediated generation of Id-loss 2C3 variants, whereas CD8+ T cells were highly cytotoxic and selectively eliminated 2C3 cells both in vitro and in vivo. These effector cells could be induced by cell membrane-associated Ig but not by its soluble form, secreted by 2C3 cells. Antibodies to MHC class I but not class II molecules were inhibitory to this induction. Furthermore, brefeldin A (BFA), an inhibitor of MHC class I mediated processing, blocked induction of CTL but had no effect on the expression of membrane Ig. Moreover, chloroquine, an inhibitor of class II-mediated processing, had no effect. A few reports have recently appeared indicating that an exogenous Ig can be processed by B-cells in the context of MHC class II proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Animais , Células Apresentadoras de Antígenos/imunologia , Antígenos CD4/imunologia , Antígenos CD8/imunologia , Linfócitos B/imunologia , Linfócitos T CD4-Positivos/imunologia , Hibridomas/imunologia , Idiótipos de Imunoglobulinas/imunologia , Região Variável de Imunoglobulina/imunologia , Sarcoma de Mastócitos/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Baço/imunologia , Linfócitos T Citotóxicos/imunologiaRESUMO
O BCG, em soluçäo lipídica, injetado por via intravenosa, foi capaz de reverter a imunosupressäo humoral provocada pelo mastocitoma P-815, em camundongos singênicos DBA/2, aumentando tanto o número de células formadoras de placas hemolíticas quanto os títulos de anticorpos hemaglutinantes do soro. Näo foram encontradas diferenças significativas nos títulos de anticorpos hemaglutinantes da classe IgG. Nenhum efeito bloqueador pôde ser notado na progressäo normal do tumor