The detection of IgG antibodies to silicone.

Following a recent report of an ELISA test for the detection of antibodies to silicone, we attempted to use the same assay in four patients with known exposure to silicone. These patients all gave similar positive results as did a number of control sera with no known silicone exposure. We conclude that this assay does not measure serum levels of antibodies to silicone.

Production of tumor necrosis factors alpha and beta by human mononuclear leukocytes stimulated with mitogens, bacteria, and malarial parasites.

Tumor necrosis factors alpha and beta (TNF-alpha and TNF-beta) are multifaceted polypeptide cytokines which may mediate some of the significant changes in cellular homeostasis which accompany the invasion of the mammalian host by viruses, bacteria, and parasites. Although it is well established that bacterial lipopolysaccharide is a potent inducer of TNF-alpha, there is still very little known of the types of agents which can trigger the production of TNFs in mononuclear leukocytes. Using an enzyme-linked immunosorbent assay for measuring TNF-alpha and TNF-beta, we examined the capacity of various T-lymphocyte and beta-lymphocyte mitogens as well as microbial components to stimulate production of these cytokines in culture. The mitogens phytohemagglutinin, concanavalin A, and pokeweed mitogen induced production of both TNF-alpha and TNF-beta, while whole-killed Staphylococcus aureus and Bordetella pertussis, like lipopolysaccharide, were potent inducers of TNF-alpha but failed to stimulate TNF-beta production. TNF-alpha production was detectable within 1 h after stimulation, while TNF-beta production was not detected until after 8 h of culture. The bacterial products tetanus toxoid, purified protein derivative, pertussis filamentous hemagglutinin, and pertussis toxin were all able to induce TNF-alpha and TNF-beta production. Disrupted (frozen-thawed) Plasmodium falciparum-infected erythrocytes were also potent inducers of TNF-alpha and TNF-beta. The results demonstrated that a wide variety of microbial components are inducers of TNF-alpha. Some may not only be more effective than lipopolysaccharide but can also induce TNF-beta production. Furthermore, evidence is presented showing that TNF-beta but not TNF-alpha production correlates with lymphoproliferation.

Tetrandrine, a plant alkaloid, inhibits the production of tumour necrosis factor-alpha (cachectin) hy human monocytes.

Human mononuclear leucocytes (MNL) or the adherent fraction (monocytes) produced tumour necrosis factor-alpha (TNF-alpha) (by ELISA) in culture when stimulated with killed Staphylococcus aureus. The bisbenzylisoquinoline alkaloid, tetrandrine inhibited the capacity of MNL and monocytes to produce TNF-alpha at a concentration range of 0.1 to 5 micrograms/ml. Tetrandrine may be potentially useful in the treatment of inflammatory diseases in which TNF-alpha plays a major role.

Depression of immunity to Naegleria fowleri in mice by selective depletion of neutrophils with a monoclonal antibody.

In an attempt to define the role of neutrophils in immunity to Naegleria fowleri in vivo, we examined the effects of treating immunized (with amoeba culture supernatant antigen) mice with the monoclonal antibody NIMP-R10, which binds to neutrophil complement receptor type 3bi (CR3) and causes selective neutrophil depletion in mice. Mice in the nonimmunized group challenged with amoebae all died by day 12, while 97% in the immunized group survived. By contrast, the immunized group treated with NIMP-R10 showed only 25% survival. The immunized group treated with "control" mouse ascites, WEM-G11, was highly resistant (90% survival). There was a significant neutrophil response in the nasal mucosa and olfactory lobes of immunized, NIMP-R10-treated mice, despite a marked degree of neutropenia similar to that seen in immunized, untreated mice. Nonimmunized mice showed virtually no neutrophil response. Despite this response in the NIMP-R10-treated mice, amoebic proliferation was not depressed, and there was no evidence of neutrophil degranulation or amoebic killing, despite the close apposition of large numbers of neutrophils to amoebae. The results indicate that neutrophils are necessary for the expression of immunity to N. fowleri.

The role of antibody in immunity against experimental naegleria meningoencephalitis ('amoebic meningitis').

Mice immunized with amoeba culture fluid (ACF) from axenically cultured Naegleria fowleri showed marked protection against a lethal amoeba challenge, a result consistent with previous observations from this laboratory. The nature of this acquired resistance is not known. The data presented show that the degree of protection conferred to mice by immunization is related to the levels of antinaegleria antibodies. These antibodies react with the surface of the amoeba. The data also show that serum (and the IgG serum fraction) from immunized mice confer protection to normal mice against a lethal N. fowleri challenge. Spleen cells from immunized animals were only capable of conferring protection to recipients, when the challenge time was delayed (10 days), at which time anti-naegleria antibodies appeared in the serum of the mice. The studies suggest that antibodies play an important role in the ACF-induced resistance to experimental naegleria meningoencephalitis.

An enzyme-linked immunosorbent assay for the quantitation of human IgG subclasses using monoclonal antibodies.

An enzyme-linked immunosorbent assay was established for the quantitation of human IgG1, IgG2, IgG3 and IgG4 using IgG subclass-specific monoclonal antibodies. The method could detect 1-10 ng/ml of the Ig subclasses. The technique is suitable for measuring IgG subclass concentration in sera of healthy adults and in supernatants from human lymphocytes cultured in the presence of pokeweed mitogen.

Depression of human polymorphonuclear leucocyte function by anti-malarial drugs.

The effect of the anti-malarial drugs quinine, chloroquine, pyrimethamine, mefloquine and quinacrine on human polymorphonuclear leucocyte (PMN) function was examined in vitro. In general, all drugs had their greatest effect on PMN iodination reaction and locomotion, intermediate effects on PMN hexose-monophosphate shunt activity, and least effect on PMN adherence. The most potent of these were pyrimethamine and mefloquine. The PMN iodination reaction and locomotion were inhibited between 0.5-1 microgram/ml (congruent to 2-4 X 10(-6) M) pyrimethamine and 1-4 micrograms/ml (congruent to 0.25-1 X 10(-5) M) mefloquine. The study demonstrates that anti-malarial drugs depress PMN functions associated with antimicrobial activity of the cell.

Inhibition of in vitro human lymphocyte response by the pneumococcal toxin pneumolysin.

The effects of pneumolysin, a sulfhydryl-activated cytolytic toxin produced by Streptococcus pneumoniae, on the in vitro human lymphocyte response was examined. The toxin, at concentrations of one to five hemolytic units per ml, caused marked inhibition of the response of lymphocytes to concanavalin A, phytohemagglutinin, pokeweed mitogen, and protein A. The response was assessed by measuring both [3H]thymidine incorporation and the ability of lymphocytes to produce immunoglobulins and lymphokine activity. The effects of pneumolysin were irreversible, could be prevented by pretreatment of the toxin with cholesterol, and were not related to a direct cytotoxic effect on the lymphocytes. Pneumolysin appeared to act at the initiation phase of the immune response and had no effect on lymphocytes committed to DNA synthesis or to the synthesis and secretion of immunoglobulins. Furthermore, pneumolysin-mediated inhibition of the lymphocyte response was not due to the inhibition of binding of mitogens to leukocytes and is likely to be related to effects on membrane-mediated signals essential for lymphocyte triggering. This may be one means by which pneumolysin plays a role in the pathogenesis of pneumococcal infections.

Activation of human complement by the pneumococcal toxin pneumolysin.

Highly purified pneumolysin (at a concentration of 10 micrograms/ml) caused significant activation of human complement, as measured by conversion of C3. Complement activation in the presence of pneumolysin was not observed in sera chelated with a combination of Mg2+ and ethylene glycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid, and activation was only slight in C2-deficient sera. This suggests that the toxin is capable of activating the classical complement pathway. Treatment of normal human serum with pneumolysin also significantly reduced its opsonic activity for Streptococcus pneumoniae.