Inhibition of human antigen-specific memory B cell response in vitro by a diphtheria toxin-related interleukin 2 fusion protein.
Recombinant diphtheria toxin-related interleukin-2 fusion protein (DAB486IL-2) is specifically cytotoxic for cells bearing the high-affinity IL-2 receptor (p55/75). We evaluated the effects of DAB486IL-2 on the generation of tetanus toxoid (TT)-specific IgG antibody-forming cells in 6-day cocultures of human splenocytes and TT-coupled Sepharose beads. The results indicate that a significant portion (30-75%) of the anti-tetanus toxoid IgG response in vitro was susceptible to inhibition by 10(-10) M DAB486IL-2. The inhibition required both the IL-2 portion of the fusion protein and an active toxin moiety and was greater when the IL-2 toxin was added on Day 3 as compared with Day 0 of culture. The induction of the p55 (Tac) subunit of the IL-2R was demonstrable by two-color flow cytometry on a small percentage (5%) of B cells and on a higher percentage (10%) of non-B cells 3 days after exposure to TT-coupled Sepharose. Short-term (2 hr) treatment of T and B cell subpopulations separated on Day 3 of culture followed by remixing indicated that while activated T helper cells were most strongly inhibited by DAB486IL-2, up to 50% of the TT-specific IgG response was inhibited by treatment of B cells alone with DAB486IL-2. Our results suggest that a strategy of eliminating human memory B cells by a combination of antigen activation and properly timed administration of a recombinant lymphokine-toxin fusion protein is feasible.
Grailer
A P
AP
Department of Surgery, University of Wisconsin, Madison 53792.
Nichols
J C
JC
Strom
T B
TB
Sollinger
H W
HW
Burlingham
W J
WJ
D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D002478:Cells, Cultured; D003429:Cross Reactions; D004167:Diphtheria Toxin / Q000276:immunology / Q000494:pharmacology*; D007074:Immunoglobulin G / Q000096:biosynthesis; D007156:Immunologic Memory; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000276:immunology / Q000494:pharmacology*; D016131:Lymphocyte Subsets; D011817:Rabbits; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*; D013745:Tetanus Toxoid / Q000276:immunology*
D004167:Diphtheria Toxin; D007074:Immunoglobulin G; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D011993:Recombinant Fusion Proteins; D013745:Tetanus Toxoid