Industrial shrimp processing discards are a potent source of natural carotenoids. This study was aimed at investigating the immunomodulating properties of astaxanthin, the major carotenoid extracted from shell discards of Arabian red shrimp Aristeus alcocki. The immunostimulatory effect of astaxanthin was determined by assaying the Splenic T-lymphocyte mitogen response, bone marrow cell proliferation assay, plaque formation cell assay, circulating antibody titre, and alpha-naphthyl acetate esterase activity in bone marrow cells at the end of 45 days feeding of the control mice with normal diet and the test animals with normal diet containing astaxanthin @ 10 mg/kg feed. In the astaxanthin treated animals, the spleen cell proliferation was found to be stimulated in the presence of mitogen. Enhanced proliferation of bone marrow cells was also observed in treated animals compared to control animals. These findings indicate induction of proliferation of bone marrow stem cells either directly or indirectly, stimulating the release of factors that are involved in the regulation of hemopoesis. The treated animals also showed an increase in number of plaque forming cells in the spleen, and antibody titer in the circulation which are the functions of B-cells. Bone marrow cells positive for non specific esterases were found to increase after astaxanthin treatment which indicates increased maturation of cells of lymphoid linkage. The present study thus reveals that oral administration of astaxanthin from A. alcocki shell discards stimulates immune function in mice through enhanced proliferation and function of immunocompetant cells.

Arsteus alcocki, astaxanthin, immunomodulating property