Activated peripheral T lymphocytes undergo apoptosis when cultured with monocytes activated by HLA class II ligation

Anti-Inflammatory Function of Nodosin via Inhibition of IL-2

In order to explore the anti-inflammatory effects of Nodosin from Isodon serra, a traditional Chinese herb medicine, mouse T lymphocytes were incubated with Nodosin. In the current study, Nodosin suppressed the overproduction of the T lymphocytes; moreover, cell mitosis cycle was modulated by interfering with DNA replication in G1 stages via inhibition of IL-2 cytokine secretion at the mRNA level by Nodosin. Interestingly, Xylene-induced mouse tumescence model results suggested Nodosin depressed the murine ear-swelling extent and the level of IL-2 in the blood serum. Finally, Nodosin possessed significant anti-inflammatory effects and is a potential candidate for further clinical trial.

Studies on the cell-immunosuppressive mechanism of Oridonin from Isodon serra

Distinct effects of Oridonin and Lasiodonin, which were extracted from Isodon serra was compared by the ratio of IC(50) versus EC(50), the therapeutic index. After choosing the more effective one, Oridonin, its immunosuppressive effect and mechanism were investigated using BALB/c mouse splenic lymphocytes both in vitro and in vivo. When murine splenic lymphocytes was incubated with Oridonin, the novel extract effectively suppress the overproduction of the cell stimulated by Concanavalin A in a dose and time-dependent manner. This inhibitive activity was mainly due to interfering DNA replication in G(1) stages and regulating cell cycle and minorly due to decreasing the CD4(+)/CD8(+) lymphocytes level, according to Flow cytometry analyses (FCAS) results. Xylene-induced mouse tumescence model result suggested that Oridonin depressed the murine ear-swelling extent and the level of Interleukin-2 in the blood serum of experimental animals. The exciting results of enzyme-linked immunosorbent assay (ELISA) indicated that Oridonin could inhibit the secretion of Interleukin-2, Interferon-gamma, Interleukin-12p40 and Tumor necrosis factor-alpha in murine splenic lymphocytes. Moreover, the results of reverse transcriptase-polymerase chain reaction (RT-PCR) confirmed that the inhibition was through decreasing the expression level of these cytokines mRNA. Consequently, the results of our research showed that Oridonin suppressed overproduction of murine splenic lymphocytes through interference of DNA replication, regulation of cell cycle and inhibition of cytokine secretion both at protein and mRNA level.

Distinct immunosuppressive effect by Isodon serra extracts

Distinct effect of ent-Kaurene Diterpenoids from Isodon serra on abnormal proliferation of murine lymphocytes was examined with MTT assay and Flow Cytometry Analyses (FCAS). After choosing the most appropriate monomer from these Diterpenoids, we introduced mouse tumescence model to investigate whether it could impact cytokine production in vivo with ELISA assay. The result of MTT assay showed that four ent-Kaurene Diterpenoids could effectively suppress the murine splenic T lymphocytes overproduction stimulated by Concanavalin A, while inhibitive effect was softer on normal sleep lymphocytes than the stimulated ones. Among four ent-Kaurene Diterpenoids, Enmein was the most sensitive one with IC50/EC50 equaling to 1.55. This inhibitive activity was due to interfering DNA replication in G1-S stage and to regulating cell cycle according to flow cytometry analyses (FCAS) result. Xylene-induced mouse tumescence model result further suggested that Enmein depressed the murine ear swelling extent and the level of Interleukin-2 in blood serum in a dose-dependent manner. In conclusion, it demonstrated that four ent-Kaurene Diterpenoids from I. serra had distinct immunosuppressive effect in vitro and in vivo systems, which primarily differentiated Enmein from the others. The experimental results provided insight into a potential immunosuppressive action of Enmein as a promising drug, though profound mechanism remained to be further studied.

IL-10-dependent down-regulation of MHC class II expression level on monocytes by peritoneal fluid from endometriosis patients

Endometriosis is a gynecologic disorder characterized by the ectopic growth of misplaced endometrial cells. Moreover, immunological abnormalities of cell-mediated and humoral immunity may be associated with the pathogenesis of endometriosis. The effects of peritoneal fluid (PF) from endometriosis patients on the expression levels of MHC class II and costimulatory molecules on the cell surfaces of monocytes were investigated. Compared to the PF of controls, the addition of 10% PF (n=10) from patients with endometriosis to culture medium significantly reduced the percentage of MHC class II-positive cells in cultures of a THP-1, monocytic cell line at 48 h. The effect of endometriosis patient PF (EPF) was dose-dependent, and similar effect was observed in peripheral blood monocytes. An inverse correlation was found between MHC class II expression level and IL-10 concentration in EPF (r=-0.518; p=0.019) and in the supernatant of peripheral blood monocyte cultured in EPF (r=-0.459; p=0.042) (n=20). The expression levels of costimulatory molecules (CD80 and CD86), but not of CD54 and B7-H1, were down-regulated by EPF. The mRNA level of HLA-DR was unaffected by EPF but protein level was reduced by EPF. Neutralizing IL-10 antibody abrogated MHC class II down-regulation on monocytes, which had been induced by EPF. However, in a functional assay, monocytes treated with EPF failed to stimulate T cell in mixed leukocyte reaction, although T cell proliferation was increased with EPF-treated monocytes and Staphylococcus enterotoxin B. These results suggest that MHC class II expression level on monocytes is down-regulated by EPF, but the cell stimulatory ability of monocytes does not coincide with MHC class II expression level.

Antigenic complementarity among AIDS-associated infectious agents and molecular mimicry of lymphocyte proteins as inducers of lymphocytotoxic antibodies and circulating immune complexes

BACKGROUND

People at risk for acquired immunodeficiency syndrome (AIDS) have high rates of cofactor infections in addition to HIV, including cytomegalovirus, hepatitis viruses, Mycobacteria, Mycoplasmas, and Staphylococcus aureus. Most people with AIDS also develop lymphocytotoxic antibodies (LCTA) and circulating immune complexes (CIC). While HIV proteins mimic HLA antigens, many cofactor agents mimic CD4 antigens. It has therefore been proposed that cofactor infections may interact with HIV by producing complementary antigens that induce LCTA and CIC, and that the resulting immunological dysfunction is part of AIDS pathogenesis.

OBJECTIVES

To test (1) whether HIV and its cofactor infections elicit complementary (idiotype-anti-idiotype) antibodies, and (2) if any of these antibodies mimic anti-lymphocyte antibodies.

STUDY DESIGN

Two immunological methods are employed to test for antibody complementarity: (1) double antibody diffusion, a modification of Ouchterlony immunodiffusion, in which antibodies are tested for their ability to precipitate each other; (2) double-antibody ELISA, in which an antibody against one infectious agent is adsorbed to an ELISA plate and an antibody against a second agent is used to detect the first.

RESULTS

Data on over a thousand double antibody diffusion (DAD) and about 70 DA-ELISA experiments are reported. These show that only specific pairs of antibodies are complementary: HIV-CMV; HIV-HBV; HIV-tuberculosis; HIV-mycoplasmas; HIV-S. aureus; and CMV-mycoplasmas. In addition, HIV antibodies precipitate CD4 antibodies; CMV antibodies precipitate HLA-DR antibodies; while mycobacteria and mycoplasma antibodies precipitate macrophage antibodies.

CONCLUSIONS

Antibodies elicited by HIV infection can interact with antibodies elicited by cofactor infections to form CIC, and some of these antibodies mimic lymphocyte antibodies so that they may function as LCTA. Since LCTA and CIC are associated with increased lymphocyte death in AIDS, the immune response against cofactors in HIV may play a significant role in AIDS pathogenesis. The fact that both HIV and cofactors elicit antibodies with LCTA characteristics may pose problems for vaccine development.