Seropositive rheumatoid arthritis with dermatomyositis sine myositis, angioimmunoblastic lymphadenopathy with dysproteinemia-type T cell lymphoma, and B cell lymphoma of the oropharynx.

Angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) is a rare lymphoproliferative disorder that often progresses to high grade T cell lymphoma. We describe a 63-year-old woman with longstanding seropositive rheumatoid arthritis who developed fever, cutaneous findings of dermatomyositis, a diffuse pruritic maculopapular rash, enlarged lymph nodes, polyclonal elevated serum gammaglobulins, and an IgG lambda paraprotein. Lymph node biopsies yielded tissue with characteristic changes of AILD and T cell lymphoma. Interleukin 6 (IL-6) was present during the early, active phase of disease, and circulating IL-6 and IL-2 were detected one month before tumor recurrence. Two years after AILD and T cell lymphoma were diagnosed, she developed a B cell lymphoma that involved the oropharynx.

De novo membranous glomerulopathy in a renal transplant patient treated with FK 506. The first reported case.

We describe a case of de novo membranous glomerulopathy in the renal allograft of a diabetic patient, treated with the newer immunosuppressive agent FK 506. Twenty-two months later this patient developed nephrotic range proteinuria.

Effects of metabolites of leukotriene B4 on human neutrophil migration and cytosolic calcium levels.

Leukotriene B4 (LTB4) is metabolized by beta-oxidation, omega-oxidation and the 12-hydroxyeicosanoid dehydrogenase/delta 10-reductase pathway. We have investigated the effects of metabolites formed by the latter pathway on calcium mobilization and migration in human neutrophils and have compared their potencies with those of other LTB4 derivatives. 12-Oxo-LTB4 and 10,11-dihydro-LTB4 were 60 to 100 times less potent than LTB4 in stimulating neutrophils, whereas 10,11-dihydro-12-oxo-LTB4 and 10,11-dihydro-12-epi-LTB4 exhibited still lower potencies. The 6-trans isomers of 12-oxo-LTB4 and 10,11-dihydro-12-oxo-LTB4 were much less potent than the 6-cis compounds. The EC50 values for biologically and chemically (6-cis) synthesized 12-oxo-LTB4 were similar, indicating that the 6,7-double bond is retained in the cis configuration in the biologically formed compound. Methylation of LTB4 markedly reduced its effect on cytosolic calcium levels, whereas addition of a 3-hydroxyl group had a much more modest effect. Modifications of the omega end of the molecule also resulted in lower potencies for calcium mobilization. Nearly all of the compounds tested desensitized neutrophils to LTB4-induced calcium mobilization, which suggests that their effects were mediated by receptors for the latter compound. However, modifications in the carboxyl end of the molecule had smaller effects on desensitization than on calcium mobilization, whereas the reverse was true for modifications in the omega end of the molecule. This suggests that the structural requirements for agonist-induced desensitization to LTB4 may differ to some extent from the requirements for calcium mobilization.

Effects of oxo and dihydro metabolites of 12-hydroxy-5,8,10,14-eicosatetraenoic acid on chemotaxis and cytosolic calcium levels in human neutrophils.

One of the pathways of metabolism of leukotriene B4 (LTB4) and 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) in leukocytes is oxidation of the 12-hydroxyl group, followed by reduction of the 10,11-double bond. In the case of 12R-HETE and 12S-HETE, this results in the formation of 12-oxo-ETE, 10,11-dihydro-12-oxo-ETE, and the 12R and 12S isomers of 10,11-dihydro-12-HETE (i.e., 12R-HETrE and 12S-HETrE). We investigated the effects of metabolites of 12-HETE formed by this pathway on cytosolic calcium levels and chemotaxis in human neutrophils. Of the above series of metabolites, 12S-HETrE (which has the same absolute stereochemistry at C-12 as 12R-HETE) was the most potent in stimulating both cytosolic calcium levels and chemotaxis. It was slightly less potent than 12R-HETE, consistent with the concept that reduction of the 10,11-double bond results in a loss of biological activity on neutrophils. The effect of 12S-HETrE on calcium levels was blocked by preincubation of these cells with LTB4, suggesting that it acted by stimulating the LTB4 receptor. 12R-HETrE was about 20 times less potent than its 12S isomer in stimulating cytosolic calcium in neutrophils and was also less active as a chemotactic agent. Oxidation of the 12-hydroxyl group to an oxo group resulted in a further loss of biological activity. 12-Oxo-ETE, 8-trans-12-oxo-ETE, and 12-oxo-ETrE had only modest effects on cytosolic calcium levels at concentrations as high as 10 microM and did not display detectable chemotactic activity. However, 12-oxo-ETE and its 8-trans isomer inhibited calcium responses to LTB4 by about 40%. It is concluded that reduction of the 10,11-double bond of 12-HETE results in a slight loss of biological activity on neutrophils, whereas oxidation of the 12-hydroxyl group results in a considerably greater loss of activity.

Stimulation of human neutrophils by 5-oxo-6,8,11,14-eicosatetraenoic acid by a mechanism independent of the leukotriene B4 receptor.

We recently identified a novel pathway for the metabolism of 5(S)-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE) by human neutrophils, resulting in oxidation of the 5-hydroxyl group to give 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) (Powell, W. S., Gravelle, F., and Gravel, S. (1992) J. Biol. Chem. 267, 19233-19241). This pathway is quite specific for 5-HETE and other eicosanoids containing a 5(S)-hydroxyl group followed by a 6-trans double bond. In the present study we have shown that 5-oxo-ETE is very potent in raising cytosolic calcium levels in human neutrophils. This effect was reproducibly observed at concentrations as low as 0.3 nM, and the EC50 was found to be 2 nM. The mechanism of action of 5-oxo-ETE on neutrophils appeared to be distinct from that of leukotriene B4 (LTB4), since it was not blocked by the LTB4 antagonist LY255283 at a concentration which completely prevented the response to LTB4. As would be expected for a receptor-mediated mechanism, the response to 5-oxo-ETE was subject to homologous desensitization and was completely abolished by prior treatment of neutrophils with 5-oxo-ETE (100 nM) but was not affected by pretreatment of these cells with the same concentration of LTB4. 5-Oxo-15(S)-hydroxy-6,8,11,13- eicosatetraenoic acid (5-oxo-15-hydroxy-ETE), formed from 5(S),15(S)-dihydroxy-6,8,11,13- eicosatetraenoic acid (5,15-di-HETE) by the pathway responsible for the formation of 5-oxo-ETE, also raised cytosolic calcium levels in human neutrophils, with an EC50 of about 15 nM. 5-HETE, the precursor of 5-oxo-ETE, also had this effect but was about 100 times less potent than the latter substance. Desensitization experiments indicated that both 5-oxo-15-hydroxy-ETE and 5-HETE act by a mechanism similar to that of 5-oxo-ETE, but different from that of LTB4. In addition to their effects on calcium levels, both 5-oxo-ETE and 5-oxo-15-hydroxy-ETE had chemotactic effects on human neutrophils. Related eicosanoids, including 15-oxo-5,8,11,13-eicosatetraenoic acid, 5,15-diHETE, and 5(S)-hydroxy-15-oxo-6,8,11,13-eicosatetraenoic acid were much less potent, as both chemotactic and calcium-mobilizing agents. These results suggest that neutrophils possess a specific recognition mechanism for 5-oxo-ETE, which may be an important regulator of the activity of neutrophils, especially if they become desensitized to LTB4.

Metabolism of 5(S)-hydroxyeicosanoids by a specific dehydrogenase in human neutrophils.

We have previously shown that human polymorphonuclear leukocytes (PMNL) convert 6-trans isomers of leukotriene B4 (LTB4) to 6,11-dihydro metabolites (Powell and Gravelle (1988) J. Biol. Chem. 263, 2170-2177). In the present study, we have shown that the first step in the formation of these dihydro metabolites is oxidation of the 5-hydroxyl group to a 5-oxo group, which is catalyzed by an NADP(+)-dependent microsomal dehydrogenase enzyme. All the dihydroxyeicosanoids we investigated which contained a 5(S)-hydroxyl group followed by a 6-trans double bond were good substrates for this reaction. However, LTB4, which contains a 6-cis double bond, was not metabolized to any detectable 5-oxo products. The preferred substrate for the dehydrogenase reaction is 5(S)-hydroxy-6,8,11,14-eicosatetraenoic acid (5(S)-HETE), which has a Km of about 0.2 microM, compared to approx. 0.9 microM for 12-epi-6-trans-LTB4. In contrast to 5(S)-HETE, 5(R)-HETE as well as a variety of positional isomers of 5(S)-HETE are not metabolized to significant extents by the PMNL dehydrogenase. 5-Oxo-ETE and 5-oxo-15-hydroxy-ETE, which are formed from 5(S)-HETE and 5,15-diHETE, respectively, by this pathway, are potent chemotactic agents for human neutrophils, and raise intracellular calcium levels in these cells.

Ventilatory effects of the interaction between phrenic and limb muscle afferents.

We studied the effects on ventilation and ventilatory muscle activation of stimulation of the central ends of the left phrenic and gastrocnemius nerves separately and concurrently in 10 spontaneously breathing, alpha-chloralose anaesthetized dogs. The nerves were stimulated for 1 min, at a frequency of 40 Hz and pulse duration of 1 ms. The phrenic nerve was stimulated at 20 and 40 times twitch threshold (TT). During these stimulation periods ventilation increased by 39% and 79% of control values, respectively. The gastrocnemius nerve was stimulated at 20 times TT. This produced a 90% increase in ventilation. Stimulation of either nerve resulted in increases in the activity of the right diaphragm, parasternal intercostal and alae nasi muscles comparable in magnitude to the increase in tidal volume. The activities of the genioglossus and transversus abdominis muscle increased to a much greater extent than did the other muscles under all conditions. In contrast, triangularis sterni activity remained unchanged during stimulation of either nerve. The phrenic nerve was then stimulated at 40 times TT for 1 min with superimposed gastrocnemius nerve stimulation (20 times TT) during the last 30 s. Ventilation had risen by 66% after 30 s of phrenic nerve stimulation. With the addition of gastrocnemius nerve stimulation, ventilation rose by a further 84% for a total increase of 150% of the control value. Mathematical summation of the responses to individual nerve stimulation at these intensities predicted a 156% increase in ventilation. Similar degrees of summation were found with respect to respiratory muscle activation. We conclude that the interaction between phrenic and limb muscle (gastrocnemius) afferent is additive with respect to their effects on ventilation.