Toxicity, membrane binding and uptake of the Sclerotinia sclerotiorum agglutinin (SSA) in different insect cell lines.

The fungal lectin purified from Sclerotinia sclerotiorum, further referred to as Sclerotinia sclerotiorum agglutinin or SSA, possesses insecticidal activity against important pest insects such as pea aphids (Acyrthosiphon pisum). This paper aims at a better understanding of its activity at cellular level. Therefore, different insect cell lines were treated with SSA. These cell lines were derived from different tissues and represent the three major orders of insects important in agriculture: CF-203 (midgut Choristoneura fumiferana, Lepidoptera), GUTAW1 (midgut, Helicoverpa zea, Lepidoptera), High5 cells (ovary, Trichoplusia ni, Lepidoptera), Sf9 (ovary cells from Spodoptera frugiperda, Lepidoptera), S2 (hemocyte, Drosophila melanogaster, Diptera), and TcA (whole body, Tribolium castaneum, Coleoptera). Although the sensitivity to SSA differs between the cell lines, SSA clearly showed toxicity in all six cell lines with median effect concentrations (EC50) ranging between 9 and 42 µg/ml. An in-depth analysis of the mechanism of uptake in the cells revealed superior amounts of FITC-SSA at the membrane of CF-203 cells compared to Sf9 cells, while a similar small amount of SSA was internalized in both cell lines. Pre-incubation with the clathrin-mediated endocytosis inhibitor phenylarsine oxide inhibited the internalization of SSA into the CF-203 and Sf9 cells with a respective reduction of 6- and 1.7-fold. The data are discussed in relation to the importance of cellular uptake mechanism for SSA binding and cytotoxicity.

Clinical syndromes associated with cold agglutinins.

Auto-immune haemolysis (AIHA) occurs when an individual's own red blood cells are destroyed by an autoantibody. Anaemia ensues if bone marrow production of red cells cannot compensate for the increased loss of red blood cells.

Management of patients with cold agglutinins who require open-heart surgery.

Cold agglutinins are commonly found in the sera of healthy persons but rarely become clinically important because most agglutinins exert their greatest reactivity at low temperatures. This report describes a patient who successfully underwent aortic valve replacement in the presence of cold agglutinins; it discusses the management of patients with cold agglutinins who undergo open-heart surgery with core hypothermia. Changes in the cell membrane occur when cold circulating antibody combines with complement and antigen present on the surface of the red cell membrane, causing intravascular hemolysis. Two conditions are necessary for the reaction to occur to any appreciable extent: there must be a high enough titre of cold agglutinin and the reactive thermal range must be attained. To avoid these conditions, the core hypothermia should not reach the reactive thermal range or the titre should be reduced either by the standard hemodilution techniques for cardiopulmonary bypass or by plasmapheresis.

Cooling mattress induced acute hemolytic anemia.

We have reported a patient with Mycoplasma pneumonia, cold agglutinins, and a hemolytic anemia which was probably secondary to vigorous treatment of hyperpyrexia by a cooling mattress. Physicians caring for patients with Mycoplasma pneumonia should be alerted to the potential untoward effect of a cooling mattress on an individual with a high titer of cold agglutinins.