| Abstract: | Chicken IgM antibodies raised against sheep erythrocytes (SE) reacted with a heterophile carbohydrate antigen designated as "HC". This antigen was visualized by SE rosette formation with antibody-sensitized and formaldehyde-fixed target cells. Cells from eight lymphoblastoid lines and ten lines of diverse histogenetic origin all expressed HC on their surface to a greater or lesser degree when grown in fetal calf serum (FCS). Lymphoblastoid cell lines, HSB2 and Namalva, lost most of their HC antigen after three cell divisions when grown in medium which contained normal human serum (NHS) instead of FCS. The acquired origin of HC was demonstrated by the conversion of HSB2-HC- into HSB2-HC+ cells after incubation in the presence of FCS or fetuin for 18 h at 37 degrees C. The acquisition of HC antigen depended on the concentration of fetuin as well as the time and temperature of incubation. The presence of NHS in the culture medium reduced the degree of HC incorporation. The level of HC expressed on the cell surface was reduced by treating HSB2 cells with sodium periodate but not by proteolytic enzymes. Competitive inhibition with hog blood group substance and sheep IgG suggested similar specificity of HC on target cells which had been sensitized with either fetuin or sheep IgM (Eur. J. Immunol. 1977.7:204). The avidity of chicken antibodies to HC in either of these systems was several orders of magnitude lower than the binding to SE. |
