Galectin-1, an alternative signal for T cell death, is increased in activated macrophages

Galectin-1 belongs to an evolutionarily conserved family of animal ß-galactoside-binding proteins, which exert their functions by crosslinking the oligosaccharides of specific glycoconjugate ligands. During the past decade, attempts to identify the functional role of galectin-1 suggested participation in the regulation of the immune response. Only in the last few years has the molecular mechanism involved in these properties been clearly elucidated, revealing a critical role for galectin-1 as an alternative signal in the generation of T cell death. In the present study we will discuss the latest advances in galectin research in the context of the regulation of the immune response, not only at the central level but also at the periphery. Moreover, we will review the purification, biochemical properties and functional significance of a novel galectin-1-like protein from activated rat macrophages, whose expression is differentially regulated according to the activation state of the cells. The novel role of a carbohydrate-binding protein in the regulation of apoptosis is providing a breakthrough in galectin research and extending the interface between immunology, glycobiology and clinical medicine

Galectins: a key intersection between glycobiology and immunology

Galectins are a family of evolutionarily conserved animal lectins, widely distributed from lower invertebrates to mammals. They share sequence and structure similarities in the carbohydrate recognition domain and specificity for polylactosamine-enriched glycoconjugates. In the last few years significant experimental data have been accumulated concerning their participation in different biological processes requiring carbohydrate recognition such as cell adhesion, cell growth regulation, inflammation, immunomodulation, apoptosis and metastasis. In the present review we will discuss some exciting questions and advances in galectin research, highlighting the significance of these proteins in immunological processes and their implications in biomedical research, disease diagnosis and clinical intervention. Designing novel therapeutic strategies based on carbohydrate recognition will provide answers for the treatment of autoimmune disorders, inflammatory processes, allergic reactions and tumor spreading.

Cells involved in the regulation of the autoimmune response to rat male accessory glands

1. The immunization of Wistar rats with 5 mg of chemically modified rat male accessory glands saline extract (MRAG) incorporated into complete Freund's adjuvant (CFA) induced a delayed type hypersensitivity (DTH) response to rate male accessory glands (RAG). Pretreatment with peritoneal cells (PC) obtained from rats 2 h after an intraperitoneal (ip) injection of a partially purified fraction (FI) of RAG (FI-PC2h) suppressed the DTH response to MRAG after immunization with MRAG-CFA, while pretreatment with PC obtained 24 h after an ip injection of FI-RAG (FI-PC24h) induced potentiation of the DTH response to MRAG. 2. The injection of spleen mononuclear cells (SpM), obtained from rats rendered unresponsive to MRAG by pretreatment with FI-PC2h, into normal syngeneic recipients markedly prevented the DTH reaction to MRAG. The transfer of SpM cells from animals injected with FI-PC24h (potentiated animals) to suppressed recipients (recipients of FI-PC2h on days -10 and -3, prior to immunization with MRAG-CFA) showed that SpM cells did not eliminate the suppression state in these recipients, but when they were transferred to normal recipients, they were able to induce a positive response to RAG (P<0.005). 3. The study of the phenotypic characteristics of the SpM cells prior to transfer showed similar numbers of CD4 and IL-2R SpM cells in both potentiated and normal animals. However, the number of CD8 cells was significantly reduced in SpM cells from potentiated animals compared to that observed in SpM cells from normal animals (P<0.05)

Induction of humoral autoimmune response to rat male accessory glands.

Ratas macho y hembra de la cepa Wistar fueron isoinmunizadas con extracto de glandulas accesorias masculinas quimicamente modificadas o sin tratamiento siguiendo diferentes esquemas.La mayoria de los animales produjeron autoanticuerpos convencionales y homocitotropicos, especificos de organo y especie. Los anticuerpos hemaglutinantes fueron 2-ME resistentes en todos los casos. La inmunizacion con el material modificado permitio detectar mayor frecuencia de respuesta y titulo de anticuerpos mas elevados (p < 0,05) sin cambiar la especificidad. La modificacion quimica del material antigenico cumple un papel adyuvant