Lymphoid Tissue and Pathological Influences of Toxicants

Toxicologic pathology plays a crucial role in the identification and interpretation of substance-induced health effects. Histology of lymphoid organs is quite sensitive, although it does not flag every model immunotoxic substance. Subtle interferences of toxic compounds, like transmembrane signaling and cell activation, are often not detectable...

Lymphoid Tissue and Pathological Influences of Toxicants

Toxicologic pathology plays a crucial role in the identification and interpretation of substance-induced health effects. Histology of lymphoid organs is quite sensitive, although it does not flag every model immunotoxic substance. Subtle interferences of toxic compounds, like transmembrane signaling and cell activation, are often not detectable...

Contact and respiratory sensitizers can be identified by cytokine profiles following inhalation exposure

There are currently no validated animal models that can identify low molecular weight (LMW) respiratory sensitizers. The Local Lymph Node Assay (LLNA) is a validated animal model developed to detect contact sensitizers using skin exposure, but all LMW respiratory sensitizers tested so far were also positive in this assay. Discrimination between...

Initiating mechanisms of food allergy: Oral tolerance versus allergic sensitization

Immediately after birth the mucosa of the gastrointestinal tract, which represents the greatest body surface area exposed to the outside environment, is confronted with a large variety of foreign antigens. The immune system of the intestine now has to meet the task of discriminating between pathogens and harmless antigens, such as food proteins...

Histopathology of mucosa-associated lymphoid tissue

Mucosa-associated lymphoid tissue (MALT) is a generalized term incorporating a disseminated collection of lymphoid tissues in multiple sites throughout the body. MALT sites that have been/are primarily studied include bronchus-associated lymphoid tissue (BALT), gut-associated lymphoid tissue (GALT), and nasopharynx-associated lymphoid tissue ...

Extended histopathology in immunotoxicity testing: Interlaboratory validation studies

There has been considerable interest in the use of expanded histopathology as a primary screen for immunotoxicity assessment. To determine the utility of a semiquantitative histopathology approach for examining specific structural and architectural changes in lymphoid tissues, a validation effort was initiated. This study addresses the...

Histopathology of a spontaneously developing mast cell sarcoma in a Wistar rat

A case report is given of a very rare spontaneous mast cell tumor in the eyelid of the left eye of a female Wistar rat used in a long-term oral toxicity study. Metastasis of the tumor had occurred in the mandibular lymph nodes and in the liver. Clinically, the animal showed blepharospasm, dacryorrhoea, and exophthalmus. Hematologic findings...

Absence of an effect of lead acetate on sperm morphology, sister chromatid exchanges or on micronuclei formation in rabbits

The influence of lead on sperm morphology, sister chromatid exchanges or on micronuclei formation was studied on male rabbits after exposure to doses of 0, 0.25, and 0.50 mg lead acetate/kg body weight subcutaneously injected three times a week during 14 weeks, each on a group of five rabbits. At the end of exposure phase the lead in blood...

Differences in uptake of adriamycin and daunomycin by normal BM cells and acute leukemia cells determined by flow cytometry

Flow cytometry was used to measure the uptake of adriamycin (AM) and daunomycin (DM) by various cell types of the haemopoietic organs and by acute myeloid leukemia (AML) cells. For this purpose, the spontaneous fluorescence of the drugs upon excitation with laser light at 488 nm was measured. The difference in the uptake of these two drugs...