Heide T. Moore

Composition and biological behaviour of immune complexes isolated from synovial fluid of patients with juvenile rheumatoid arthritis (JRA)

Data published from In vitro studies have shown that IgM‐rheumatoid factor (RF)‐bearing immune complexes possess several biological features that may contribute to their pathogenicity. However, no studies have demonstrated that such complexes exist at sites of inflammation in children with rheumatoid disease. We used two methods of sequential column chromatography to purify immune complexes from synovial fluids of children with JRA. We demonstrate that high molecular weight complexes contain IgM‐RF, have not bound C4 in vivo, but activate the classical pathway in vitro. In contrast, complexes which have bound C3 in vivo do not contain IgM‐ RF and are weak complement activators in vitro.

Fetal cytokine expression in utero detected by reverse transcriptase polymerase chain reaction.

ABSTRACT: Cytokine expression at the maternal-fetal interface is well documented. Some authors have postulated the existence of a bidirectional cytokine signaling mechanism that is critical to the maintenance of normal pregnancy. The role of the fetus (versusfetally derived placental tissues) in this process is unknown. Using reverse transcription polymerase chain reaction techniques, we studied paired maternal and fetal samples from 16 pregnancies (including two twin pregnancies) for the presence of tumor necrosis factor-α and IL-1β mRNA. We demonstrate that mRNA for both of these cytokines can be detected in both maternal and fetal blood as early as the 21st wk of gestation. These results support a potential role for the fetus in the bidirectional cytokine signaling of pregnancy.

Human choriocarcinoma JAR cells constitutively express pro-interleukin-1β that can be released with Fcγ receptor engagement

Some authors have suggested that fetally derived syncytiotrophoblasts, which form the barrier between mother and the fetus, are an integral part of a complex macrophage-cytokine network involving maternal leukocytes, decidual cells, placental tissues, and even the fetus itself. We report here that syncytiotrophoblast-like JAR cells, a human choriocarcinoma cell line, share another feature common to cells of the monocyte-macrophage lineage, the ability to secrete IL-1β when stimulated through their Fcγ receptors. We incubated JAR cells with physiologically relevant concentrations of model BSA-rabbit IgG-anti-BSA immune complexes or monomeric rabbit IgG for periods of up to 72 h. Both monomeric IgG and immune complexes induced IL-1β from JAR cells, although levels produced by immune complexes were approximately twice those induced by monomeric IgG. IL-1β secretion was not inhibited by cycloheximide, and Western blots of JAR cell lysates using pro-IL-1β MAb revealed constitutive expression of a 31-kD protein, whose levels declined within 2 h of stimulation by either IgG or immune complexes, but returned to baseline within 18 h.

Expression of complement regulatory proteins on fetal blood cells in utero

Since the fetus is semiallogenic to the mother, mechanisms have evolved to protect fetal tissue from the maternal immune response. Among these mechanisms is the expression of cell-surface complement regulatory proteins at the maternal-fetal interface. However, beginning in the third trimester, fetal blood cells are exposed to actively-transported IgG antibody. Thus, we speculated that fetal blood cells would require expression of one or more complement regulators by the early third trimester. Using flow cytometry and Western blots, we have demonstrated the presence of three important complement regulatory proteins in the circulating blood cells of human fetuses. These findings are consistent with the putative biological role of the cell-surface complement regulatory proteins.

Constitutive Expression c-fos, c-jun, and NFκB mRNA Is in Nucleated Fetal Blood Cells and Up-Regulation of c-fos and c-jun with Anti CD3 Stimulation

Fetal and neonatal lymphocytes are relatively resistant to activation and cytokine production when stimulated either via their T-cell antigen receptors or lectins. The molecular mechanism(s) responsible for this phenomenon have not been clearly elucidated. We have hypothesized that such defects in fetal/neonatal T-cell activation may be due to lack of expression of the transcriptional regulatory elements required for T-cell activation. We used reverse transcriptase-polymerase chain reaction to examine both fetal and term neonatal cord bloods for mRNA expression of three transcription factors implicated in T-cell activation: c-jun, c-fos, and NF kappa B (p50 subunit). We demonstrate that mRNAs for all three of these regulatory factors are expressed in fetal blood cells by the 27th week of gestation and in term cord bloods. Activation of term infant cord blood mononuclear cells with anti-CD3 monoclonal antibodies resulted in up-regulation of both c-jun and c-fos mRNAs within 15 min of stimulation. However, secretion of IL-2 by anti-CD3-stimulated cord blood mononuclear cells was still blunted compared with control cells from adults. We conclude that fetal nucleated blood cells constitutively express important genes for cytokine regulation and are able to increase intracellular accumulation of the mRNAs for these factors in response to anti-CD3 stimulation. Thus, qualitative differences in the capacity to regulate these factors could not be shown in fetal blood cells. Quantitative experiments comparing binding of these transcription factors to the IL-2 promoter are currently under investigation.

rtPCR ANALYSIS OF ONCOGENE AND TRANSCRIPTION FACTOR EXPRESSION IN NUCLEATED FETAL BLOOD CELLS . • 1714

rtPCR ANALYSIS OF ONCOGENE AND TRANSCRIPTION FACTOR EXPRESSION IN NUCLEATED FETAL BLOOD CELLS . • 1714

TROPHOBLAST-LIKE JAR CELLS CONTAIN PRO-IL-1 |[beta]| WHICH IS RELEASED WITH Fc|[gamma]|R ENGAGEMENT. |[dagger]| 351

There is considerable interest in the role of cytokines in pregnancy and the initiation of labor. IL-1β, IL-6, and TNFα have been detected in amniotic fluid late in the second trimester, and levels rise until term. Trophoblasts bear many similarities to monocytes, and they are likely sources of cytokines at the maternal-fetal interface. We examined trophoblast-like JAR cells to determine whether they secrete the cytokine IL-1β with Fcγ receptor cross-linking, as do normal monocytes.