Human anti-endotoxin antibody HA-1A mediates complement-dependent binding of Escherichia coli J5 lipopolysaccharide to complement receptor type 1 of human erythrocytes and neutrophils.

HA-1A has been shown clinically to decrease mortality in septic patients with gram-negative bacteremia. In this study, the ability of HA-1A to augment the serum complement-dependent immune adherence of 125I-labeled Escherichia coli J5 lipopolysaccharide (LPS) to human erythrocytes (RBC) and polymorphonuclear leukocytes (PMNL) was evaluated. In vitro studies indicated three things: HA-1A mediates immune adherence of 125I-J5 LPS to human RBC and PMNL in a dose-dependent manner; under these conditions, high concentrations of LPS (400 ng/mL) could be specifically bound. Immune adherence occurs via the classical complement pathway as demonstrated by its calcium dependence; HA-1A-J5 LPS-C' immune complexes bound to CR1 on human RBC and PMNL. PMNL binding and internalization of immune complexes was demonstrated by trypsin stripping of externally bound immune complexes. These studies support the proposal that HA-1A can lower the bioavailability of endotoxin by mediating binding and potential clearance of LPS via human RBC through the reticuloendothelial system or via direct internalization by peripheral blood PMNL.

Binding of antibody and resistance to lysis of trypomastigotes of Trypanosoma cruzi.

Epimastigote forms of Trypanosoma cruzi are readily lysed by complement via the alternative pathway. Neither fibroblast-derived trypomastigotes nor blood-form trypomastigotes are lysed by complement alone and few (less than 30% of the Brazil strain) are lysed in the presence of parasite-specific antibody and complement. The mechanism by which trypomastigotes resist antibody-dependent, complement-mediated lysis is not clearly understood. In the present study, we have utilized flow cytometric analysis to examine the binding of parasite-specific antibody to epimastigotes, fibroblast-derived trypomastigotes and blood-form trypomastigotes of a Brazil strain of T. cruzi. We also determined the extent of lysis of these parasites in the presence of complement utilizing propidium iodide to determine cell death. It was found that all epimastigotes bind approximately the same amount of antibody but that there are subpopulations of trypomastigotes which bind antibody to varying degrees. When these subpopulations were sorted, and treated with complement, lysis was only minimally increased in the population of parasites which bound significantly greater amounts of antibody.

Cryotherapy of proliferative sickle retinopathy, II: triple freeze-thaw cycle.

Complete closure of retinal neovascularisation due to proliferative sickle cell retinopathy was achieved in 28 'sea fans' (areas of neovascularisation) in 9 eyes of 9 patients by means of a triple freeze-thaw technique. However, 2 eyes developed subsequent rhegmatogenous retinal detachments, presumably related to vitreous traction on necrotic retina. We therefore recommend photocoagulation as the best treatment of proliferative sickle cell retinopathy. If opacities in the media prevent photocoagulation, a single freeze-thaw cycle is preferable.

Peptostreptococcal endophthalmitis with a relapsing course.

A posttraumatic exogenous endophthalmitis developed that was due to Peptostreptococcus. This Gram-positive anaerobe was isolated in pure culture from vitreous. The endophthalmitis showed a bacteriologic and clinical relapse despite conventional routes of antimicrobial treatment. A second clinical relapse occurred despite apparent vitreal sterilization with intravitreal antibiotics. The response to vitrectomy was impressive, and postoperatively the patient's visual acuity improved to 20/20.

The anatomic basis for glaucoma.

The greatest bulk of aqueous passes through a sieve-like trabecular wall to reach Schlemm's canal. The vacuoles of the endothelial lining of the trabecular wall are pressure-dependent one-way valves, adapted morphologically to provide for adequate aqueous transfer. Resistance to aqueous outflow seems to be most concentrated in the juxtacanalicular tissue which is also the site of the greatest mucopolysaccharide concentration and phagocytic activity. Normal intraocular pressure may be maintained through a balance between hydrophilic polymerized MPS and hydrophobic depolymerized MPS. It may be effected also by a phagocyte-induced, self-cleaning biologic filter mechanism of the trabecular wall. The use of electron microscopy and improved biochemical techniques have led recently to a greater understanding of the anatomy of the structures concerned with the outflow of aqueous from the anterior chamber. Despite these advances, no clear-cut differences between normal and glaucomatous eyes have emerged thus far. However, the future should bring more knolwedge as the stimulus of conflicting theories leads to progress.

An unusual presentation of Best's disease.

We diagnosed an unusual case of Best's disease in a patient with multiple geographic macular and extramacular lesions. Initial confusion in the diagnosis arose because of a past history of intravenous drug abuse by the patient. The electro-oculogram was helpful in establishing the correct diagnosis.