The incidence of latex sensitivity in ambulatory surgical patients: a correlation of historical factors with positive serum immunoglobin E levels.

Increasing reports of latex-induced anaphylaxis make preoperative identification of latex-sensitive individuals an important concern. The incidence of latex sensitivity and the efficacy of questionnaires in identifying this in ambulatory surgical populations have not been determined. To clarify these issues, 996 ambulatory surgical patients were studied preoperatively. A questionnaire addressing demographic information, previous surgeries, history of atopy, previous exposure or reactions to latex, congenital abnormalities, and food allergies was administered. These data were then compared with serum anti-latex immunoglobin E (IgE) levels (AlaSTAT test), and risk factors, sensitivity, and specificity were determined. Of this population, 6.7% had IgE antibodies against latex (i.e., latex sensitivity). Male gender, non-Caucasian race, age, asthma, spinal cord abnormalities, food allergies, stated latex allergy, and symptoms when exposed to latex increased the risk of latex sensitivity. The specificity and positive predictive value of history were low. No systemic allergic reactions occurred, a finding that could be attributed to chance alone. The incidence of latex sensitivity in this population suggests that latex allergy is a significant potential problem in ambulatory surgical patients. History, however, does not appear to be a reliable predictor of the presence of anti-latex antibodies.

A comparison of the fibrinogen receptor distribution on adherent platelets using both soluble fibrinogen and fibrinogen immobilized on gold beads.

The distribution of fibrinogen receptors was determined on the surface of adherent platelets using both direct labeling with the ligand fibrinogen which was immobilized on gold particles (Fg-Au) and indirect immunogold (Ig-Au) labeling of bound soluble fibrinogen identified with a rabbit polyclonal anti-fibrinogen antibody. Two distinctly different patterns of labeling were obtained and appeared to depend on whether solid phase fibrinogen (Fg-Au) or soluble phase released fibrinogen were bound to the membrane receptor. The membrane-bound Fg-Au reorganized in patterns that closely mimicked the organization of the underlying cytoskeleton. In approximately 18% of the adherent platelets, Fg-Au was seen in channels or vesicle-like structures lying deep to the platelet surface suggesting internalization into the open canalicular system and/or endocytosis. The labeling pattern obtained when identifying the location of membrane-bound soluble released fibrinogen by Ig-Au was diffuse and lacked the organizational patterns characteristic of Fg-Au. Unlike the Fg-Au probe, early dendritic platelets were heavily labeled by the soluble phase fibrinogen using the Ig-Au technique. Although the label covered the entire exposed platelet membrane in fully spread platelets, labeling over the peripheral web was more dense than that over the intermediate or granulomere zone. The diffuse organization and heavier peripheral distributional pattern of the glycoprotein IIb-IIIa (GP IIb-IIIa) receptor in fixed, adherent platelets, was also seen with the GP IIb-IIIa receptor-specific antibody AP-2. The binding of both the Fg-Au and Ig-Au were inhibited using the tetrapeptide Arg-Gly-Asp-Ser (RGDS) (93% and 98% inhibition, respectively), AP-2 (98% and 97%, respectively) and platelets from patients with Glanzmann's thrombasthenia (GT) (99% and 98%, respectively). The data presented provides the first report that receptor reorganization, following binding of fibrinogen, appears to be related to the state of the ligand. Substrate bound fibrinogen (i.e., Fg-Au or fibrinogen bound to another platelet) induces receptor translocation toward the platelet granulomere in a capping-like phenomenon. On the other hand, the binding of soluble released fibrinogen results in formation of microclusters and short linear arrays in a diffuse distribution but does not induce central movement of receptors. Furthermore, double labeling studies clarify that Fg-Au does not identify all available fibrinogen receptors as many are occupied by soluble released fibrinogen. The data presented provides an interesting new perspective on what constitutes an appropriate ligand-receptor stimulus sufficient to induce receptor reorganization.