Characterization of onion lectin (Allium cepa agglutinin) as an immunomodulatory protein inducing Th1-type immune response in vitro

Prasanna Vaddi, K. and Venkatesh, Y. P. (2015) Characterization of onion lectin (Allium cepa agglutinin) as an immunomodulatory protein inducing Th1-type immune response in vitro. International Immunopharmacology, 26. pp. 304-313.

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Abstract

Onion (Allium cepa), a bulb crop of economic importance, is known to have many health benefits. The major ob- jective of the present study is to address the immunomodulatory properties of onion lectin (A. cepa agglutinin; ACA). ACA was purified from onion extract by D-mannose-agarose chromatography (yield: ~1 mg/kg). ACA is non-glycosylated and showed a molecular mass of ~12 kDa under reducing/non-reducing SDS-PAGE; glutaralde- hyde cross-linking indicated that ACA is a non-covalent tetramer of ~12 kDa subunits. Its N-terminal sequence (RNVLLNNEGL; UniProt KB Accn. C0HJM8) showed 70–90% homology to mannose-specific Allium agglutinins. ACA showed specific hemagglutination activity of 8200 units/mg and is stable in the pH range 6–10 and up to 45 ° C. The immunomodulatory activity of ACA was assessed using the macrophage cell line, RAW264.7 and rat peritoneal macrophages; at 0.1 μg/well, it showed a significant increase (6–8-fold vs. control) in the production of nitric oxide at 24 h, and significantly stimulated (2–4-fold vs. control) the production of pro-inflammatory cy- tokines (TNF-α and IL-12) at 24 h. ACA (0.1 μg/well) enhanced the proliferation of murine thymocytes by ~4 fold (vs. control) at 24 h; however, ACA does not proliferate B cell-enriched rat splenocytes. Further, it significantly elevated the expression levels of cytokines (IFN-γ and IL-2) over the control in murine thymocytes. Taken togeth- er, purified ACA induces a Th1-type immune response in vitro. Though present in low amounts, ACA may contrib- ute to the immune-boosting potential of the popular spice onion since considerable amounts are consumed on a daily basis universally.

Item Type:	Article
Uncontrolled Keywords:	Hemagglutination, Immunomodulation, Lymphoproliferation, Macrophage activation, Onion lectin, Th1-type immune response
Subjects:	600 Technology > 01 Medical sciences > 10 Immunology 600 Technology > 08 Food technology > 23 Vegetables > 05 Onion
Divisions:	Dept. of Biochemistry
Depositing User:	Somashekar K S
Date Deposited:	11 Mar 2025 06:44
Last Modified:	11 Mar 2025 06:44
URI:	http://ir.cftri.res.in/id/eprint/19264

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