Kelly L. McGarity

Prostaglandins formed by the cyclooxygenase (COX) enzymes are important mediators of inflammation in arthritis. The contribution of the inducible COX-2 enzyme to inflammation in rat adjuvant arthritis was evaluated by characterization of COX-2 expression in normal and arthritic paws and by pharmacological inhibition of COX-2 activity. The injection of adjuvant induced a marked edema of the hind footpads with coincident local production of PGE2. PG production was associated with upregulation of COX-2 mRNA and protein in the affected paws. In contrast, the level of COX-1 mRNA was unaffected by adjuvant injection. TNF-alpha and IL-6 mRNAs were also increased in the inflamed paws as was IL-6 protein in the serum. Therapeutic administration of a selective COX-2 inhibitor, SC-58125, rapidly reversed paw edema and reduced the level of PGE2 in paw tissue to baseline. Interestingly, treatment with the COX-2 inhibitor also reduced the expression of COX-2 mRNA and protein in the paw. Serum IL-6 and paw IL-6 mRNA levels were also reduced to near normal levels by SC-58125. Furthermore, inhibition of COX-2 resulted in a reduction of the inflammatory cell infiltrate and decreased inflammation of the synovium. Notably, the antiinflammatory effects of SC-58125 were indistinguishable from the effects observed for indomethacin. These results suggest that COX-2 plays a prominent role in the inflammation associated with adjuvant arthritis and that COX-2 derived PGs upregulate COX-2 and IL-6 expression at inflammatory sites.

This study was undertaken to determine the effects of continuous corticosterone administration on lymphocyte subsets in the peripheral blood of Fischer 344 rats. Pellets which released corticosterone over a 21 day period (0.07 mg/day, 0.48 mg/day and 4.8 mg/day) were implanted subcutaneously in male rats. Control rats received pellets containing only the excipient carrier. Rats in the test and control groups were sacrificed at 7, 14 and 21 days. Lymphocyte subsets were enumerated by dual color flow cytometry and the data expressed in absolute numbers/mm3. Effects were observed only in the animals treated with the highest dose which was 70,000 times the normal plasma level. The spleen, thymus and lymph nodes were examined for histopathological changes. At the seven day sacrifice there was a statistically significant decrease in total white blood cells and selective decrements in lymphocytes with reductions in the absolute numbers of the T helper/amplifier, T cytotoxic/suppressor and B cells. Only numbers of natural killer cells were within normal limits. Histopathological data from animals treated with the high dose corticosterone for seven days demonstrated decreased thymic weights and a loss of thymic lymphocytes. At 14 and 21 days, the numbers of lymphocytes returned to the normal range, but the numbers of total T cells remained decreased. Also, thymic weights were reduced but not histological abnormalities were observed in the thymus. The data suggest that corticosterone induced a persistent decrease in total T cells, but only a transient effect on total lymphocytes.

In vitro radioallergosorbent tests have not been useful in identification of subjects with symptomatic allergic responses to acid anhydrides. By using phthalic anhydride or tetrachlorophthalic anhydride conjugated to human serum albumin, a study was undertaken to determine whether histamine release from basophils or lymphocyte transformation correlated with clinical symptoms, circulating anhydride specific IgE, and skin test reactivity. The data demonstrate that only histamine release from basophils correlated with symptoms and skin test reactivity. We conclude that in vitro histamine assays can be used in the identification of subjects with allergic responses to anhydrides.

Using in vitro assays, this study was undertaken to determine whether the components of Lasso herbicide formulation had an effect on the human immune system. Mononuclear cells from human peripheral blood were exposed to analytical alachlor, alachlor conjugated to human serum albumin or Lasso formulation over a concentration range from .01 microM-1.0 microM. The effects of the test materials on the following immunological functions were determined: lymphocyte proliferation induced by mitogen or antigen; antibody synthesis of IgG and IgM isotypes in pokeweed stimulated mononuclear cell cultures; cytotoxic T cell proliferation; lysis of target cells by natural killer cells and lymphokine activated killer cells. The data demonstrated that the test compounds had no significant, dose related effect on the function of immunocompetent cells. Hence, the data suggest that the components of the Lasso formulation have no effect on the human immune system.

BACKGROUND: Progenipoietin-4 (ProGP-4) is an E. coli derived chimeric growth factor that activates the human Flt3 and G-CSF receptors. ProGP-4 possesses cross-species activity and treatment of mice with ProGP-4 results in increases in the number of WBC and Class II+/CD11c+ cells in both spleen and peripheral blood. Herein, we report morphologic, phenotypic and functional evaluation of Class II+/CD11c+ cells generated by in vivo administration of ProGP-4. MATERIAL/METHODS: C57BL/6 mice were injected daily with ProGP for 7 to 18 days. Leukocytes from spleen and peripheral blood were analyzed by flow cytometry to enumerate and characterize changes in DC populations. Spleens from ProGP treated mice were evaluated by immunocytochemistry and enriched CD11c+ populations were functionally assessed in a mixed lymphocyte assay and in an antigen dependent CTL assay. RESULTS: Administration of this dual receptor agonist to mice resulted in dose-dependent increases in the numbers of total white blood cells and Class II+/CD11c+ cells in spleen and peripheral blood. CD11c+ cells from ProGP-4 treated mice co-expressed DEC205 and also expressed CD80, CD86 and CD40, albeit at lower levels as compared to Class II+/CD11c+ cells from untreated animals. Despite lower co-stimulatory molecule expression, ProGP-4-generated Class II+/CD11c+ cells stimulated proliferation of allogeneic T cells and an antigen-specific T cell hybridoma as efficiently as bone marrow derived dendritic cells from untreated mice. CONCLUSIONS: The data presented in this report highlight the ability of E. coli derived ProGP-4 to expand large numbers of functional DC in the peripheral blood and lymphoid organs in vivo using a rodent model of hematopoiesis. E. coli derived chimeric receptor agonists such as ProGP-4 may enable further investigations of immunotherapeutic approaches to the treatment of diseases such as cancer and autoimmunity.