Drug-Induced Type 1 and Type 2 Immune Responses are Characterized by Distinct Profiles of Cell Kinetics, Cytokine Production, and Expression of Co-Stimulatory Molecules in the Popliteal Lymph Node Assay

Abstract

Some drugs have the undesired side effect of systemically stimulating the immune system, which may eventually lead to the development of drug-induced allergy or autoimmunity. Unfortunately, validated predictive screening tools to assess the immune stimulatory potential of compounds are presently unavailable. The popliteal lymph node assay (PLNA) with reporter antigens (RA) seems a valuable candidate for this purpose. The aims of the present study were 1) to provide additional mechanistic information on the very early induction phase of drug-induced type 1 (TH1-associated) and type 2 (TH2-associated) immune reactions in the PLNA and 2) to explore the use of these mechanism-based parameters to predict the immune stimulating potential of drugs. Streptozotocin (STZ), a chemotherapeutic drug, and D-Penicillamine (D-Pen, anti-rheumatic drug) were used as model compounds as they respectively induce clearly differentiated type 1 and type 2 immune responses in the PLNA. Type 1 responses were characterized by the production of high levels of IFNγ and IL-12 from day 2 after exposure. Expression of CD40 was absent, but CD54, CD80, and CD86 were present predominantly on non-B APC, presumably macrophages. Increased percentages of activated CD8+ T-cells and macrophages accompanied these phenomena. Type 2 responses were clearly different and were characterized by an early influx of dendritic cells (DC) and B-cells that expressed CD40, CD54, and CD86, but no CD80. First DC, but later B-cells, appeared to function as APC. In addition, the production of IL-4 was elevated. Apparently, reactivity of these type 1- and type 2-inducing drugs produce drug-specific patterns of immune stimulating factors that determine very different, time-dependent profiles of activated cells, cytokine production, and expression of co-stimulatory molecules very shortly after the initial exposure to drugs. As such, these parameters obtained with the PLNA may help to provide information about the immunological mechanisms in the early induction phase of drug-induced immune stimulation and may be useful in the development of an appropriate screening test to predict the immune stimulatory potential of drugs in a preclinical phase.