About the Lectin

Saline extracts of soybean meal contain a potent hemagglutinin. This lectin reacts stronger with type A 1 cells than with A 2 cells. The lectin was originally purified using conventional techniques such as ion-exchange and hydroxylapatite chromatography. The purified lectin is a complex mixture of at least 5 tetrameric isolectins, containing various combinations of a, b, and g subunits, exhibiting varying degrees of C-terminal truncation. 1 The isolectins have similar hemagglutinating activities, and are immunologically indistinguishable. A gene encoding a 253-residue mature subunit has been cloned, sequenced, and expressed, with or without its high-mannose oligosaccharide, in various expression systems. 2,3 X-Ray crystal structures of the lectin complexed biantennary LacNAc structures have been determined. 4 The yield of purified material can be increased through the use of affinity chromatography. SBA has a slight preference for α-linked sugars and contains four complementary binding sites / protein. SBA reacts more strongly with neuraminidase treated glycoconjugates, indicating a preference for terminal carbohydrates. The lectin exhibits mitogenic activity towards neuraminidase treated human and mouse lymphocytes 5 . Lyophilization of the lectin reportedly promotes the formation of polymeric forms which are more mitogenic for porcine lymph node cells than the non-lyophilized preparation. SBA does not agglutinate normal mouse, human, and rat cell lines but corresponding transformed cell lines are agglutinated 6 . The lectin will agglutinate mouse spleen B cells but not T cells 7 . SBA has been found to be useful for the transplantation of bone marrow across histo-compatibility barriers 8,9 . Human bone marrow, depleted of mature T cells by sequential treatment with SBA followed by E-rosette depletion, has been used successfully in transplantation experiments, leading to full recovery of marrow function. The marrow grafts help to prevent graft vs. host disease commonly associated with mismatched tissue types. SBA has a high affinity for many different tumor cells and has been investigated as a tumor purging agent for autologous bone marrow transplants. 10

REFERENCES

  1. Mandal, D. K., et al. (1994) Eur. J. Biochem. 221 : 547-553
  2. Vodkin, L. O., et al. (1983) Cell 34 : 1023-1031
  3. Adar, R., et al. (1997) Eur. J. Biocehm. 249 : 684-689
  4. Olsen, L.R., et al. (1997) Biochemistry 36 : 15073-15080
  5. Lotan, R., et al. (1973). Biochem. Biophys. Res. Comm. 55 : 1347-1355.
  6. Sela, B. -A., et al. (1970). J. Membr. Biol. 3 : 267-279.
  7. Reisner, Y., et al. (1976). Biochem. Biophys. Res. Comm. 72 : 1585-1591.
  8. O’Reilly, R. J., et al. (1985). Transplant. Proc. 17 : 455.
  9. Collins, N. H., et al. (1992) Prog. Clin. Biol. Res. 377 : 427-439
  10. Schain, L. R., et al. (1994) J. Hematotherapy 3 : 37-46.

Product Characteristics
Buffer 0.01M Phosphate – 0.15M NaCl, pH 7.2-7.4
Blood Group A1 > A2 >> B
Activity Less than 4 μg/ml will agglutinate fresh A1 cells. Older B cells can be stronger than A2 cells.
Inhibitory Carbohydrate Terminal α- and β- N-acetyl‑D‑galactosamine. SBA also reacts with galactose.
Molecular Weight Aggregate MW=120,000. A single band of MW=30,000 by SDS-PAGE.