Presence of autoantibody for phospholipase inhibitory protein, lipomodulin, in patients with rheumatic diseases

The activity of phospholipase inhibitory protein, lipomodulin, partially purified from rabbit neutrophils, was markedly decreased after treatment with sera from patients with rheumatic diseases such as systemic lupus erythematosus, rheumatoid arthritis, and dermatomyositis. The decrease of the protein's inhibitory activity on phospholipase A2 paralleled the amount of [35S]methionine-labeled lipomodulin precipitated by the sera. Absorption of patients' sera with anti-human IgM (mu chain) or protein A-agarose, but not with anti-human IgG (gamma chain), decreased their ability to decrease the activity of lipomodulin on phospholipase A2 or to precipitate the radioactive lipomodulin. The IgM fraction of patients' sera could precipitate [35S]methionine-labeled lipomodulin (40,000 daltons) which comigrated with highly purified lipomodulin on gel electrophoresis with sodium dodecyl sulfate. All of these observations suggest that the sera of many patients with rheumatic diseases contain autoantibody against lipomodulin. A monoclonal antibody against lipomodulin was also obtained. Stimulating human fibroblasts with bradykinin in the presence of monoclonal antilipomodulin antibody markedly enhanced arachidonic acid release due to the activation of phospholipase(s) in the intact cells, and this stimulatory effect was blocked by adding purified lipomodulin. These findings suggest that lipomodulin regulates the activity of phospholipase(s) on the cell surface and that autoantibodies against lipomodulin may play a role in certain symptoms of rheumatic diseases, especially by the formation of prostaglandins and other metabolites of arachidonic acid.

Antibodies to T cells in patients with systemic lupus erythematosus can induce antibody-dependent cell-mediated cytotoxicity against human T cells

Patients with active systemic lupus erythematosus (SLE) often have circulating antibodies to T cells. These patients also often have leukopenia and diminished numbers of T lymphocytes. In addition, certain T lymphocyte functions are frequently impaired in patients with SLE. It has been previously considered that a complement-dependent cytotoxic mechanism was responsible for the above observations. We now demonstrate that antibody-dependent cell-mediated cytotoxicity (ADCC), a cytotoxic reaction mediated by antibody and effector cells in the absence of complement, can also kill T cells from normal individuals as well as from patients with SLE. Moreover, this ADCC could be observed using the plasma, effector cells, and target cells all obtained from the same individual with SLE. Plasma of those patients with active SLE, and in whom anti-T cell antibodies could be demonstrated by the more classical complement-dependent cytotoxicity, was most often able to mediate such an ADCC reaction. The IgG fraction of the plasma was responsible for inducing ADCC, and aggregated IgG could block the reaction. The fact that the IgG fraction was often more effective than the unfractionated plasma suggested that immune complexes present in SLE plasma might partially block the expression of ADCC. Because a single SLE plasma could induce ADCC in T cells from several different unrelated individuals, it is unlikely that antibodies directed against particular human leukocyte antigens (HLA) or blood group antigens are involved.

Power and energy measurements of transient electric discharge

A simple and inexpensive calculating device for electrical power and energy of transient electric discharges is described. The calculation is made by multiplication of the voltage and current of the discharge by use of wideband integrated circuits.

Identification of urinary metabolites of human subjects exposed to o-dichlorobenzene

o-Dichlorobenzene (o-DCB) has adverse effects on the liver and kidney in animals. It also causes some irritation to the eyes and the upper respiratory system in humans. This study aimed to identify urinary metabolites of human subjects exposed to o-DCB. Urine samples were collected from three male workers exposed to o-DCB and were analyzed using a gas chromatograph-mass spectrometer. 2,3- and 3,4-dichlorophenols and 3,4- and 4,5-dichlorocatechols were detected in all the samples. Some amounts of the four metabolites were presumably present as conjugates, because they increased after heating with hydrochloric acid.