Clare Pinto

lnterleukin-2 Promotes the Motility of Dendritic Cells and Their Accumulation in Lung and Skin

Dendritic cells (DC) play a critical role as antigen-presenting cells in vivo. It has previously been shown that DC accumulate in the lung in response to parenteral injections of IFN-gamma. In the current paper, we report that rat DC express the interleukin-2 receptor (IL-2R) alpha-chain (OX-39) and display enhanced motility in response to IL-2 in Boyden chamber and video time-lapse microscopy assays. Increased motility was specifically inhibited by pretreating DC with OX-39 (anti-IL-2R) but not OX-22 (anti-CD45RC), an isotype-matched murine monoclonal antibody. The intratracheal injection of IL-2 increased the number of OX-6+ dendritic cells located around pulmonary venules and in the lung interstitium. When IL-2 was injected into the footpad of the rat. DC were increased around dermal venules at 24 h. This effect was blocked by the parenteral injection of anti-OX-39. We conclude that IL-2 is a potent enhancer of DC motility and may cooperate with other T helper(h)-1 proinflammatory cytokines in attracting DC to sites of inflammation.

Adoptive immunotherapy with IL-2 results in the loss of delayed-type hypersensitivity responses and the development of immediate hypersensitivity to recall antigens☆

Skin testing represents a direct method of assessing immune responses in vivo. Twenty-six patients with metastatic cancer of the lung, kidney, or melanoma were treated with adoptive transfers of autologous tumor-infiltrating or blood lymphocytes and continuous infusions of interleukin-2 (IL-2). Prior to therapy, cutaneous anergy to recall antigens was observed in 19 patients (73%), whereas 6 (27%) displayed normal delayed-type hypersensitivity (DTH) responses. When tested again at the end of therapy, DTH responses could not be elicited in any of the patients. Proliferative responses to skin test antigens, lectins, and IL-2 diminished progressively during therapy but returned to baseline values at 1 month. Unexpectedly, 14 of these patients (53%) developed immediate skin test responses to candida antigens and 5 (19%) to mumps antigens. These immediate responses were characterized by local erythema and induration that developed within minutes of injecting antigen. Biopsies displayed marked dermal edema and infiltration by eosinophils. Although serum IgE levels were not increased, immediate reactivity could be transferred by a heat-sensitive serum factor. The implications of this novel response are uncertain, and its development did not correlate directly with the anti-tumor effects of therapy. We conclude that adoptive immunotherapy with IL-2 produces a reduction in cutaneous DTH and diminished responses to mitogens while simultaneously promoting cutaneous allergy. We hypothesize that this may reflect diminished IL-2 production by antigen-specific helper T cells and that other lymphokines may promote these immediate hypersensitivity responses.

Interferon-Gamma and Tumor Necrosis Factor-Alpha Promote the Binding of Dendritic Cells to Fibronectin

Connective tissue dendritic accessory cells (DC) accumulate at sites of extracellular matrix (ECM) deposition. The adherence of DC to purified ECM proteins was examined. Splenic and pulmonary DC were purified from Lewis rats and incubated on slides coated with fibronectin (FN), laminin (LN), or collagen (COLL) types I, III and IV. In other experiments, DC were pre-incubated with selected proinflammatory cytokines (IL-1, IL-2, IFN-gamma, TNF-alpha) in order to determine their abilities to modulate cell adherence to ECM. Both splenic and pulmonary DC showed dose-dependent binding to FN that was inhibited by the synthetic peptide arg-gly-asp-ser. There was minimal DC binding to LN or COLL. Pretreating DC with IFN-gamma or TNF-alpha enhanced DC binding to FN but did not increase binding to LN or COLL. IL-1 and IL-2 had no demonstrable effect on DC binding to ECM. Our results suggest that FN is a critical ligand for DC in their binding to the ECM. IFN-gamma and TNF-alpha increase adherence of DC to FN and may promote their accumulation in the lung during inflammation.

Adoptive immunotherapy with interleukin-2 (IL-2) results in diminished IL-2 production by stimulated peripheral blood lymphocytes

We examined the responses of peripheral blood lymphocytes (PBL) to a panel of T-cell mitogens in patients receiving adoptive transfers of tumor-infiltrating lymphocytes and continuous infusions of interleukin-2 (IL-2) for treatment of advanced cancer. All patients showed diminished proliferative responses to soluble and alloantigens, lectins, anti-CD3, and IL-2 during therapy. The non-major histocompatibility complex (MHC)-restricted cytolytic activities of PBL were increased by treatment and were further augmented by IL-2in vitro. The expression of ≈55-kd low-affinity IL-2 receptors (IL-2R) by PBL increased during treatment but functional IL-2R were simultaneously down-regulated. Proliferative responses were partially restored to pretreatment levels when PBL were costimulated with recombinant IL-2 and mitogens. Lectin stimulation of PBL produced little IL-2 secretion during treatment, while IFN-gamma secretion persisted. We conclude that infusions of IL-2 down-regulate the expression of functional IL-2R, decrease the secretion of IL-2, and lead to decreased mitogen responses by PBL.