title: Biologic activity of antigen receptors artificially incorporated onto B lymphocytes.
abstract: We describe a method for incorporating monoclonal antibody molecules onto viable murine lymphocytes and summarize the biologic activity of these artificial receptors on B cells. Mouse spleen cells incubated overnight with palmitate conjugates of a monoclonal anti-DNP IgA (protein 315) in the presence of deoxycholic acid incorporate about 50,000 antibody molecules per cell. When concentrations of deoxycholate and palmitoyl-protein 315 are carefully controlled, this labeling procedure does not affect the viability or the normal functions of the receptor-decorated cells. The incorporated antibody specifically binds DNP-antigens, although it appears to be unable to communicate directly with internal cellular components. Yet when these receptor-decorated, unprimed cells are challenged with any one of several DNP-antigens, up to 42,000 per 10(6) B cells differentiate into Ig-secreting cells. This response is about 23-fold greater than that induced in normal cell cultures and is of the same magnitude as that induced by the polyclonal B cell activator LPS. This, in addition to the observation that only about 3.6% of receptor-decorated B cells responding to DNP-conjugated polymerized flagellin (DNP-POL) produce hapten-specific antibody, demonstrates that these antigens cause polyclonal B cell differentiation. Normal spleen cells in the presence of DNP-POL and irradiated spleen cells bearing the artificial receptors do not exhibit the polyclonal antibody response. Also, the response of receptor-decorated B cell is blocked by high but nontoxic concentrations of the nonimmunogenic hapten DNP-lysine. These observations demonstrate that the polyclonal B cell response in this system requires the binding of antigen to artificial receptors on functionally viable cells. The polyclonal B cell response to a thymus-dependent antigen DNP-conjugated bovine gamma-globulin (DNP-BGG) requires the presence of the carrier-primed T cells. On the other hand, T cell depletion by anti-Thy-1.2 monoclonal antibody and complement causes only a slight reduction in the number of receptor-decorated B cells that respond to the relatively thymus-independent antigen DNP-POL. This type of phenomenon is also seen with natural antigen-specific B cells. Thus, polyclonal activation of receptor-decorated B cells exhibits the same gross helper cell requirements as antigenic activation of natural antigen-specific B cells. The results of this study are discussed in the context of the role of membrane-bound surface Ig in antigen-dependent B cell activation.(ABSTRACT TRUNCATED AT 400 WORDS)
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation; D002470:Cell Survival; D004136:Dinitrobenzenes / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D000939:Epitopes; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D051379:Mice; D008954:Models, Biological; D010168:Palmitates; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D004136:Dinitrobenzenes; D000939:Epitopes; D010168:Palmitates; D011947:Receptors, Antigen, B-Cell