Galectins are a family of carbohydrate-binding proteins with an affinity for beta-galactosides. Galectin-1 (GAL1) is differentially expressed by various normal and pathological tissues and appears to be functionally polyvalent, with a wide range of biological activity. The intracellular and extracellular activity of GAL1 has been described. Evidence points to GAL1 and its ligands as one of the master regulators of such immune responses as T-cell homeostasis and survival, T-cell immune disorders, inflammation and allergies as well as host-pathogen interactions.It also can agglutinate red blood. In this case, chose rabbit erythrocyte (RaE) to assay its ability of agglutination. A general procedure for hemagglutination assay (or haemagglutination assay; HA) is as follows, two-fold dilute the recombinant human GAL1 with 0.9% sodium chloride injection, add 50μL a serial dilution of GAL1 to each well of a U or V-bottom shaped 96-well microtiter plate. The final well serves as a negative control without GAL1, replace with 50μL 0.9% sodium chloride injection. Then add 50μL 1% rabbit erythrocyte to each well and mixed gently. The plate is incubated for 3 hours at room temperature. The results are shown in Figure 1. It was obvious that the minimal effective concentration of GAL1 is 2.5μg/mL.

Figure 2. The hemagglutination assay of GAL1 in V- bottom shaped 96-well microtiter plate.