Delayed hypersensitivity testing as a clinical measure of cell-mediated immunity in the cat.

The purposes of this study were to examine the cell-mediated immune response of the normal cat to the modified live feline viral rhinitis, calicivirus, and parvovirus (FVRCP) vaccine (Felocell CVR, Norden, Lincoln, NE), and to evaluate the intradermal skin test as a clinical measure of the immune response of cats. Vaccine and diluent were injected intradermally on the dorsal pinna of 34 normal adult cats. Skin thickness measurements, lymphocyte counts, and Concanavalin A mitogenesis indices were evaluated in 18 of these cats. Skin biopsies were obtained in 16 cats. In normal cats, the FVRCP vaccine induced a delayed hypersensitivity response characterized by a mononuclear infiltrate most pronounced at 72 h. Five cats with either feline leukemia (FeLV) or feline immunodeficiency virus (FIV) were tested and had a significantly reduced response to the skin test. The skin test provides a clinically useful method of evaluating immune function in cats and may be useful in development of a prognostic index.

An immunofluorescence test to determine the occurrence of type II collagen in muscle biopsies from cattle with rectovaginal constriction.

Type II collagen occurs in the muscles of rectovaginal constriction (RVC) affected and carrier cattle but not in normal cattle. Muscle biopsies from known RVC affected and carrier cattle and normal cattle were examined for the presence of Type II collagen using affinity purified goat anti-collagen II serum in a fluorescent antibody test. Type II collagen was consistently found in RVC affected animals (22 of 23 samples score positive). Rectovaginal constriction carrier animals had variable staining for the Type II collagen (25 of 47 samples scored positive). Some positive staining was also observed in the control animals (8 of 34 samples scored positive). Because of the variable occurrence of Type II collagen, the value of fluorescent antibody staining to identify RVC carrier animals is uncertain.

Leukocyte function in Pelger-Huët anomaly of dogs.

Leukocyte function was evaluated in five dogs with Pelger-Huët (P-H) anomaly and in five control dogs. No significant differences were found between groups in neutrophil adherence, random movement, chemotaxis, phagocytosis, or bacterial killing of Staphylococcus intermedius. Neutrophils migrated rapidly into inflammatory sites where progressive nuclear lobulation was noted over time. Antibody titers to exogenous antigens were similar in the P-H and control groups indicating B- and T-lymphocyte cooperation in humoral immunity. Lymphocyte blastogenesis to phytohemagglutinin also was similar in both groups suggesting the presence of a responsive T-lymphocyte population. These findings indicate that no apparent predisposition to infection or immunodeficiency exists in dogs with P-H anomaly.

Six complementation classes of conditionally lethal protein synthesis mutants of CHO cells selected by 3H-amino acid.

Using a tritiated amino acid suicide procedure designed specifically to select conditional protein synthesis mutants, we have isolated and characterized a large number of such mutants of Chinese hamster ovary cells. All of the mutants are genetically stable and behave as recessives in somatic cell hybrids. Most of the new mutants are phenotypically dependent on the concentration of a specific amino acid as well as on temperature. In addition to identifying many additional leucyl- and asparagyl-tRNA synthetase mutants, complementation analysis has distinguished four new genetic classes representing methionine-, glutamine-, histidine-, and arginine-dependent mutants. Biochemical characterization of representative mutants from each of these six classes has identified the primary lesions as being defective aminoacyl-tRNA synthetases. Our selection results further demonstrate the high specificity of the 3H-amino acid procedure for isolating protein synthesis mutants. Reconstruction experiments performed with two representative mutants indicated a selection efficiency of approximately 10% under standard conditions.

A CHO-cell mutant with a defect in cytokinesis.

In a selection procedure designed to enrich for temperature-sensitive mutant cells blocked in mitosis a CHO-cell mutant was isolated which has a defect in cytokinesis as the basis of its temperature-sensitive phenotype. Cultures of the mutant had an abnormally high percentage (ie. 34%) of polyploid cells at the permissive temperature of 34 degress C and showed further increased frequencies of polyploidy as well as many multinucleated cells at 38.5 degrees 39.5 degrees. When the mutant cells were synchronized in metaphase by Colcemid arrest and then placed into fresh medium at nonpermissive temperature, they did not divide although the completion of mitosis appeared cytologically normal. Ultrastructural examination by electron microscopy of such synchronized cells at telophase revealed no specific defects in cellular components other than failure of development of a normal midbody. The sensitivity of the mutant to cytochalasin B and to Colcemid was the same as for wild-type cells. This mutation behaved as recessive in tetraploid cell hybrids constructed by fusing the mutant with a CHO strain which was wild-type with respect to temperature sensitivty.