Direct demonstration of murine thymus-dependent cell surface endogenous immunoglobin.

Abstract

Antisera raised in mammals to murine immunoglobulin (Ig) do not detect surface Ig on thymus-dependent (T) lymphoma cells as assessed by immunofluorescence analysis. Chicken antibodies, produced against the (Fab)2 fragment of normal mouse IgG and purified by binding to and elution from IgG-Sepharose 4B, give strong indirect fluorescence with murine T cells and cultured T lymphoma cells. The surface Ig caps are shed and reappear, indicating that they are of endogenous origin. Nonlymphoid tumor cells of various myeloid types do not bind this reagent, even though they bear avid Fc receptors. The capacity of chicken antibodies to bind to bone-marrow-dependent and T cell lymphomas was abolished by adsorption with myeloma-derived .kappa. chains coupled to Sepharose. The .kappa. antigenic determinant recognized by the chicken antibodies may thus be different from that seen by mammalian antibodies, and the degree of exposure of the Ig on the T lymphoma surface might also affect ease of detectability with these reagents. T lymphocytes and T lymphoma cells apparently express and synthesize surface Ig containing determinants that at least cross-react with bone-marrow-cell-derived .kappa. chains.