Evidence of large particle allergen inhalation from contact with surfaces.

BACKGROUND: To establish a more accurate relationship between dust mite allergen on surfaces such as bedding with respiratory uptake, an exposure method is needed which correlates exposure of allergen on surfaces with respiratory dose. OBJECTIVES: Assess if aerodynamically large allergen particles (> 10 microm), similar in nature to dust mite allergen, is inhaled into the nose from direct head-and-hand contact with allergen contaminated surfaces. METHODS: Short ragweed pollen (20-microm diameter) was used as a surrogate for dust mite allergen exposure because of its similar aerodynamic and physiologic properties. Pillows and a section of linoleum (followed by a hand press) were embedded with 99MTechnetium labeled pollen. Particles on the linoleum were transferred to the sampler after a hand press to the surface. Simulated human exposure was performed by surface-sampling particles, at a capture velocity of the nose, onto a filter. Human evaluation of hand transfer to the nose or direct inhalation from a pillow was performed with three subjects. Percentage respiratory uptake and deposition location was determined by gamma camera imaging. RESULTS: Simulated respiratory uptake of pollen by hand-to-nose transfer and directly off pillows was 20% and 1.4%, respectively. Human subject respiratory uptake by hand-to-nose transfer and directly off pillows was 6.6% and 1.5%, respectively. Most of the regional activity was found immediately in the nasal vestibule with 13% to 39% of the total activity localized in the pharyngeal region. CONCLUSIONS: Aerodynamically large allergen particles (pollen) are inhaled and deposited into the anterior nose and pharyngeal areas of the respiratory tract from direct contact with allergen-containing surfaces.

Does inhaled pollen enter the sinus cavities?

BACKGROUND: While there is evidence of an increased incidence of sinusitis in patients with allergic rhinitis, it is unclear whether an allergic process occurs in the sinus tissues per se. OBJECTIVE: The purpose of this study was to determine whether inhaled pollen reaches the sinus mucosa. METHODS: Tc99m labeled ragweed pollen was inhaled by five non-atopic adults. Imaging studies of the sinuses were performed with a tomographic rotating gamma camera. To determine the sensitivity of the technique, the nose and the maxillary sinuses of cadaver heads were painted with varying amounts of Tc99m and then similarly scanned. RESULTS: Scans of the cadaver heads showed clear resolution between the nasal cavity and the maxillary sinus. It was determined that 20 microci was the smallest amount of Tc99m that could be resolved to be in the sinuses. Scans of subjects showed intense activity in the nasal cavity but none in the paranasal sinuses despite the delivery of a supraphysiologic dose of Tc99m ragweed pollen. CONCLUSION: Inhaled ragweed pollen does not appear to enter the paranasal sinuses. It is unlikely that an inhaled antigen-IgE antibody reaction occurs in the sinus mucosa.

Indium-labeled white blood cells apheresed from donors receiving G-CSF localize to sites of inflammation when infused into allogeneic bone marrow transplant recipients.

G-CSF administration to normal donors results in granulocyte apheresis yields generally greater than those observed with other neutrophil mobilizing agents. In vitro, neutrophils cultured with G-CSF exhibit prolonged survival; however, the random migration of neutrophils exposed to this agent is inhibited. Although transfused neutrophils mobilized with agents other than G-CSF migrate to sites of inflammation or infection in vivo, this has yet to be demonstrated with infusion of G-CSF-mobilized neutrophils into neutropenic human subjects. Five neutropenic allogeneic bone marrow transplant (BMT) patients each received a fresh infusion of G-CSF-mobilized indium-labeled irradiated white blood cells (WBC) apheresed from HLA-matched normal donors on day +5 post-transplant. Localization of activity on delayed scintigraphic images of indium-labeled WBC scans to sites of tissue damage (oral/nasopharynx in two patients with mucositis and terminal ileum/cecum in one with diarrhea) occurred, and supports the hypothesis that G-CSF-mobilized HLA-matched donor neutrophils which have been irradiated are functional after infusion into neutropenic recipients.

Detection of lung rejection with indium-111-labeled lymphocytes in heterotopic rat heart-lung transplantation.

To determine if acute lung rejection after heart-lung transplantation can be detected noninvasively with indium-111-labeled (111In) lymphocytes, we studied 33 allogeneic and 18 isogeneic heterotopic heart-lung transplants in rats. Twenty-four hours after injection of isogeneic splenic 111In-lymphocytes (75 +/- 2 microCi/100 million cells), animals were scanned at 2 to 8 days after transplant (Tx). Also, percent indium uptake of the graft was determined and compared with pathologic lung changes. Between the vascular and destructive phases of lung rejection, 111In-lymphocyte uptake of lung allografts was significantly greater than isografts (p less than 0.001). Lung allografts in the alveolar phase (4-6 days after Tx) showed the most intense uptake (2.7 +/- 0.1%) of injected 111In-lymphocytes. All scintigrams of allografts from the late vascular to the early destructive phase (3-7 days after Tx) showed visualization of the lung graft (27/27 true positive, sensitivity = 100%). In contrast, lung isografts of the same period showed no pathological sign of rejection and were only rarely visualized (12/14 true negative, specificity = 86%). Lung rejection may be accurately assessed noninvasively by gamma scintigraphy with 111In-lymphocytes. This technique may prove useful in the detection of acute lung rejection in human heart-lung transplant recipients. Modification of the labeling dose chosen may further improve scan accuracy.

Significance of diffuse cardiac activity on In-111 labeled leucocyte scans.

To assess the significance of diffuse cardiac activity (DCA) seen on In-111 labeled leukocyte scans, we reviewed 87 studies performed over the last 4 years. Inflammatory cardiac conditions were seen as frequently in patients with DCA (15%) as those without (7%, P = 0.3). There was a higher ratio of RBC:WBC in the final WBC preparation in the false-positive DCA group than the true positive DCA and no DCA groups. False-positive studies showing DCA are most likely due to residual blood pool activity.

Tropolone: a lipid solubilizing agent for cationic metals.

Lipid soluble agents which chelate radioactive cations have several potential uses in nuclear medicine including: brain imaging, labeling of blood elements, and identifying fatty infiltration of organs. A tropolone-gallium complex has been characterized by the determination of in vitro partition ratios correlated with in vivo organ distribution in the rat. Partition ratios were determined for gallium-67 citrate, indium-114m chloride, and iron-59 chloride cations complexed with tropolone in chloroform + water, octanol + water, olive oil + water, and olive oil + plasma two-phased systems. Tropolone proved to be highly effective in the lipid solubilization of these metal cations. Distribution studies in animals of these cations complexed with tropolone demonstrated an increased concentration of these cation complexes in tissues of high lipid content when compared with appropriate controls.

Mechanism of hepatic extraction of gelatinized 99m technetium sulfur colloid.

Hepatic extraction, cellular and subcellular localization of gelatin stabilized Tc-99m sulfur colloid was studied in the rat model with time sequenced microautoradiography from 15 min to 24 h following I.V. administration of the tracer. Hepatic lobular and cellular distribution, quality and quantity of focal grain pattern, grain clusters, remained essentially constant for the period of study. Grain clusters were associated predominantly with Kupffer cells lining the peripheral segment of hepatic lobular sinusoids. Subcellular localization of gelatinized Tc sulfur colloid, stained prior to the I.V. administration with osmium tetroxide, was demonstrated with a transmission electron microscope in unosmicated liver tissue. Extracted Tc sulfur colloid particles were attached in groups to cytoplasmatic membranous intrasinusoidal projections of activated Kupffer cells. Intracytoplasmatic phagocytosis was not demonstrated. The kinetic arrest and en groupe extraction of Tc sulfur colloid particles at the Kupffer cell membrane suggests a specific membrane receptor site and specific Tc sulfur colloid particle-plasma protein interaction at the time of extraction. Hepatic extraction of gelatinized Tc sulfur colloid thus reflects primarily extra and intra hepatic hemodynamics and does not serve as an indicator of phagocytic hepatic reticuloendothelial system function.

An ultrafiltration technique for labeling red blood cells with Tc-99m.

This method automates the preparation of autologous Tc-99m labeled red blood cells utilizing the Amicon on-line column eluate concentrator to separate the plasma from the red blood cells. The red blood cells were pre-tinned with stannous diphosphonate and continuously recirculated over a 0.6 mu filter until all of the plasma was removed and the red blood cells remained suspended in a solution of 0.9% sodium chloride. Once the plasma has been removed the red blood cells are incubated with Tc-99m pertechnetate. The above Tc-99m red blood cells were compared to Tc-99m red blood cells produced in a similar manner except that centrifugation was used to separate the red blood cells from the plasma. Both preparations had a tagging efficiency of 98% or greater and rat distribution studies demonstrate that both preparations are equally stable as an in vivo intravascular agent.