Natural rubber latex in medical devices and consumer products has been implicated in over 1100 anaphylactic reactions that resulted in at least 15 deaths between 1988 and 1992 (1, 2). These reactions are caused by proteins that elute from the surfaces of certain latex products, especially gloves, barium enema catheters, balloons, and condoms. The proteins bind to antigen-specific IgE on tissue mast cells and trigger an anaphylactic response. While the production of IgE to latex proteins can occur in any individual, some individuals with uniquely high exposure to latex products appear to be at significantly greater risk for the production of these antibodies than the general population. These include health care workers and children with spina bifida (3-5). Interestingly, there appears to be significant clinical and immunochemical cross-reactivity between some latex proteins and allergens in certain fruits and vegetables, such as banana, kiwi, avocado, and potato, and patients with fruit and vegetable allergy may be at increased risk for reacting to latex proteins (6 -10).Latex allergy can be a devastating disease, with serious and occasionally fatal outcomes. The only treatment is avoidance (11,12), and health care workers with severe latex allergy may be required to change careers or leave health care entirely to avoid potentially dangerous exposure. Since anaphylactic episodes have occurred following skin testing with crude latex extracts (13-16), immunotherapy is not possible with currently available crude preparations. The identification and isolation of pure antigens, and the analysis of the B-and T-cell epitopes of these antigens, will facilitate the design and testing of safer regimens of immunotherapy.The proteins in natural rubber latex are derived from the commercial rubber tree, Hevea brasiliensis. Latex is produced in laticifers, which are specialized structures that consist of anastamosed latex-producing cells. Harvested Hevea latex is a complete cytosol with a high protein content (17, 18). Hevea latex is typically ammoniated when tapped to prevent premature coagulation and bacterial growth. Ammoniated latex is the source material for most of the products that elicit allergic reactions; thus, it clearly contains immunogenic material. However, immunochemical studies with ammoniated latex have failed to reveal the wealth of IgE-binding proteins found in non-ammoniated latex (NAL) 1 (19), which is collected into a liquid nitrogen-cooled container.From the first observations that products made from Hevea latex can elicit catastrophic allergic reactions in susceptible individuals, the component allergens have eluded conclusive identification. In part, this has been due to the complexity and instability of the proteins of Hevea latex. In addition, many investigators have been unable to obtain quantities of fresh material for examination and have been limited to the use of finished products or ammoniated latex (19) for their studies. In spite of these difficulties, several potential allergens have been i...

The glp operons of Escherichia coli are negatively controlled by the glp repressor. Comparison of the repressor-binding affinities for consensus and altered consensus operators in vivo showed that all base substitutions at positions 3, 4, 5, and 8 from the center of the palindromic operator caused a striking decrease in repressor binding. Substitutions at other positions had a severe to no The proteins that catalyze the steps required for the utilization of glycerol, glycerol-3-phosphate (glycerol-P), and glycerophosphodiesters are encoded by the glp regulon of Escherichia coli (14). The glp regulon is composed of five operons located at three different regions on the linkage map of E. coli. Transcription of the glp operons is negatively regulated by the glp repressor, a tetrameric protein encoded by the glpR gene (13,17). Negative control is mediated by binding of the glp repressor to its operator sites within the glp operons. The affinity of the repressor for its operators is decreased in the presence of glycerol-P, the inducer for the regulon (14). Thirteen operators have been identified in the glp operons by using DNase I footprinting (12,22,23). The operators match more or less well the consensus operator 5'-WATGTTCGWT AWCGAACA TW-3' (W is A or T, and the dot indicates the center of symmetry) (22). Tandemly repeated repressor-binding sites are present in the control regions of the glpA CB, glpD, and glpFKX operons (12,20,22,23 Cloning of operator DNA. Plasmid vector pGEM3Z (Promega) was digested with BamHI and Pstl and purified following electrophoresis on low-gelling-temperature agarose. Equimolar amounts of the oligonucleotides to be cloned were mixed in 10 mM Tris-HCl (pH 8)-50 mM NaCl-1 mM EDTA and heated to 85°C. The annealing mixture was allowed to cool to room temperature for several hours. A 40-fold molar excess of annealed oligonucleotides was mixed and ligated (3 h) to 150 ng of cleaved vector DNA in 0.04 ml. An aliquot of the ligation mixture was used for transformation of strain DH5otF'.

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