Inhibition of human natural killer activity by antiserum against vitamin D-binding protein, a group-specific component (Gc).
An anti-Gc antiserum (anti-Gc) was prepared by immunizing rabbits with purified Gc, a major vitamin D-binding protein in human serum. Gc is expressed on the surfaces of a small proportion of resting T cells and almost all B cells are natural killer (NK) cells. We investigated the effects of anti-Gc on NK activity of normal peripheral blood lymphocytes. Both anti-Gc and purified IgG isolated from anti-Gc prominently inhibited human NK activity in vitro. Inhibition of anti-Gc was dependent on the concentration of the antiserum employed. Competition assay showed that purified Gc significantly blocked the inhibitory effect of anti-Gc. The inhibition of NK activity in the cells treated with anti-Gc was restored time-dependently by being cultured in anti-Gc free medium. Anti-Gc-treated NK cells retained their capacity to bind to target cells. These findings suggest that mGc is associated with the process of the NK cytolysis on the post-binding cytolytic phase.
Chujo
T
T
Department of Clinical Research, Osaka University, Japan.
Machii
T
T
Tagawa
S
S
Kuratsune
H
H
Ueda
E
E
Kimura
H
H
Kitani
T
T
D003601:Cytotoxicity Tests, Immunologic; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology*; D007694:Killer Cells, Natural / Q000276:immunology*; D014809:Vitamin D-Binding Protein / Q000276:immunology*
D007106:Immune Sera; D014809:Vitamin D-Binding Protein