Selective immune redirection in humans with ragweed allergy by injecting Amb a 1 linked to immunostimulatory DNA.

BACKGROUND: In animal models administration of immunostimulatory DNA sequences preferentially elicits T(H)1-dominated (type 1-dominated) immunity and can inhibit developing or ongoing T(H)2 (type 2) responses. OBJECTIVE: Our objective was to investigate this phenomenon in humans. METHODS: In a randomized, third party-blinded, placebo-controlled, proof-of-concept study conducted entirely in the winter in 19 adults with ragweed allergy, we administered 6 subcutaneous injections of purified Amb a 1 linked to the 22-base-long immunostimulatory phosphorothioate oligodeoxyribonucleotide 1018 (Amb a 1-immunostimulatory DNA sequence conjugate [AIC]). Before the course of AIC or placebo injections and 2 and 16 weeks afterward, we measured recall responses to ragweed, streptokinase, and PHA in short-term primary culture of fresh PBMCs after restimulation with antigen. We quantified regulatory cytokine and chemokine responses characteristic of T(H)2 immunity (IL-5, IL-13, CCL17 [TARC], and CCL22 [MDC]), and T(H)1 immunity (IFN-gamma, CXCL9 [Mig], and CXCL10 [IP-10]), as well as IL-10, a cytokine sometimes linked to regulatory T-cell populations. RESULTS: We demonstrated for the first time that human systemic in vivo ragweed-specific T(H)2 responses were selectively redirected toward T(H)1 responses, with significant increases in IFN-gamma, CXCL9, and CXCL10 and significant decreases in IL-5, CCL17, and CCL22 found at 2 and 16 weeks after the sixth injection. Cytokine and chemokine responses to the unrelated bacterial antigen streptokinase and the global capacity to mount immune responses on polyclonal activation with PHA did not change. No clinically significant systemic or local allergic reactions were associated with AIC or placebo injections. CONCLUSIONS: AIC, injected in concentrations that were approximately 40-fold lower than those used in most murine studies published to date, led to a prolonged shift from T(H)2 immunity toward T(H)1 immunity and appeared to be safe. This novel approach has the potential for immune redirection in human immediate hypersensitivity diseases.

Chemokines in Kawasaki disease: measurement of CCL2, CCL22 and CXCL10.

Kawasaki disease (KD) is a childhood-onset vascular disease. In order to determine whether KD is associated with altered chemokine production, we measured CCL2, CCL22, and CXCL10 levels in the serum of KD patients and healthy control subjects. The mean serum concentration of CCL2 in KD subjects was 829.0 +/- 388.2 pg/ml, significantly higher than that seen in healthy controls (223.4 +/- 92.6 pg/ml; p < 0.001). In addition, the mean serum CXCL10 level in KD subjects was 2,469.4 +/- 998.8 pg/ml, again significantly higher than that in healthy controls (127.7 +/- 64.2 pg/ml; p < 0.001). No difference was observed in serum concentrations of CCL22 between KD and healthy controls (1,685 +/- 1,985 microg/ml and 1,539 +/- 380 microg/ml, respectively). Thus, we observed the selective induction of a TH1-associated (CXCL10) and a TH2-associated chemokine (CCL2) in the serum of individuals with KD, suggesting a mixed TH1/TH2 response at the level of chemokine production and subsequent cell recruitment and thus pointing at a potential role for these chemokines in the pathology of KD.

FDC-SP, a novel secreted protein expressed by follicular dendritic cells.

To define better the molecular basis for follicular dendritic cell (FDC) function, we used PCR-based cDNA subtraction to identify genes specifically expressed in primary FDC isolated from human tonsils. In this work we report the discovery of a novel gene encoding a small secreted protein, which we term FDC-SP (FDC secreted protein). The FDC-SP gene lies on chromosome 4q13 adjacent to clusters of proline-rich salivary peptides and C-X-C chemokines. Human and mouse FDC-SP proteins are structurally unique and contain a conserved N-terminal charged region adjacent to the leader peptide. FDC-SP has a very restricted tissue distribution and is expressed by activated FDCs from tonsils and TNF-alpha-activated FDC-like cell lines, but not by B cell lines, primary germinal center B cells, or anti-CD40 plus IL-4-activated B cells. Strikingly, FDC-SP is highly expressed in germinal center light zone, a pattern consistent with expression by FDC. In addition, FDC-SP is expressed in leukocyte-infiltrated tonsil crypts and by LPS- or Staphylococcus aureus Cowan strain 1-activated leukocytes, suggesting that FDC-SP can also be produced in response to innate immunity signals. We provide evidence that FDC-SP is posttranslationally modified and secreted and can bind to the surface of B lymphoma cells, but not T lymphoma cells, consistent with a function as a secreted mediator acting upon B cells. Furthermore, we find that binding of FDC-SP to primary human B cells is markedly enhanced upon activation with the T-dependent activation signals such as anti-CD40 plus IL-4. Together our data identify FDC-SP as a unique secreted peptide with a distinctive expression pattern within the immune system and the ability to specifically bind to activated B cells.