Comparison of peptide-major histocompatibility complex tetramers and dextramers for the identification of antigen-specific T cells.

Fluorochrome-conjugated peptide-major histocompatibility complex (pMHC) multimers are widely used for flow cytometric visualization of antigen-specific T cells. The most common multimers, streptavidin-biotin-based 'tetramers', can be manufactured readily in the laboratory. Unfortunately, there are large differences between the threshold of T cell receptor (TCR) affinity required to capture pMHC tetramers from solution and that which is required for T cell activation. This disparity means that tetramers sometimes fail to stain antigen-specific T cells within a sample, an issue that is particularly problematic when staining tumour-specific, autoimmune or MHC class II-restricted T cells, which often display TCRs of low affinity for pMHC. Here, we compared optimized staining with tetramers and dextramers (dextran-based multimers), with the latter carrying greater numbers of both pMHC and fluorochrome per molecule. Most notably, we find that: (i) dextramers stain more brightly than tetramers; (ii) dextramers outperform tetramers when TCR-pMHC affinity is low; (iii) dextramers outperform tetramers with pMHC class II reagents where there is an absence of co-receptor stabilization; and (iv) dextramer sensitivity is enhanced further by specific protein kinase inhibition. Dextramers are compatible with current state-of-the-art flow cytometry platforms and will probably find particular utility in the fields of autoimmunity and cancer immunology.

Suspected ehrlichial infection in five cats from a household.

Ehrlichiosis is a poorly recognized condition of cats that may be associated with anemia, leukopenia, thrombocytopenia, or dysproteinemia. Affected cats may have indirect fluorescent antibody titers to Ehrlichia canis and E risticii. We reviewed the clinical evaluation and response to treatment of 5 cats in a household where ehrlichial disease was suspected as the cause of recurrent leukopenias and thrombocytopenias. All of the cats had E risticii indirect fluorescent antibody titers and western blot confirmation of antibodies to 4 of the 9 major antigens of E risticii. Response to doxycycline was monitored serologically and hematologically in each cat, and indicated that administration of doxycycline at a dosage of 10 mg/kg of body weight, PO, every 12 hours, for a minimum of 21 days is necessary for treatment of this condition.

A confirmatory study of the relation between self-reported complex partial epileptic signs, peak experiences and paranormal beliefs.

Data obtained from a sample of 102 university students were used to calculate Pearson product moment correlations between measures of complex partial epileptic signs, peak experiences and paranormal beliefs. Significant correlations ranging from .35 to .42 (p < .001) were found between all three measures. Moreover, notable relations were obtained between complex partial epileptic signs and a number of subscales of the paranormal measure including precognition (r = .43), psi beliefs (r = .40), spiritualism (r = .40), extraordinary life forms (r = .26) and superstition (r = .22). The results are consistent with previous research linking temporal lobe signs to paranormal and peak experiences.

Evaluation of fetal infection and abortion in pregnant ponies experimentally infected with Ehrlichia risticii.

Fetal infectivity of Ehrlichia risticii was investigated in 19 ponies that were E risticii negative on the basis of results of an indirect fluorescent antibody (IFA) test. Thirteen pregnant ponies were infected by IV administration of E risticii between 90 and 180 days of gestation. Six pregnant ponies served as noninfected controls. Each infected pony had clinical signs of equine monocytic ehrlichiosis, was confirmed to be ehrlichemic, and developed an IFA titer to E risticii. Two infected ponies became recumbent, were unresponsive to supportive care, and were euthanatized. After recovery from clinical illness, the remaining ponies were observed throughout gestation for reproductive abnormalities. On abortion, each fetus was necropsied and tissue specimens from the liver, bone marrow, spleen, colon, and mesenteric lymph nodes were inoculated into canine monocyte cell cultures. Six infected ponies aborted at a mean 217 days of gestation, which was between postinoculation days 65 and 111. Five fetuses were recovered for evaluation, and E risticii was isolated from 4 of them. All 5 fetuses recovered had similar histologic finding, including enterocolitis, periportal hepatitis, and lymphoid hyperplasia with necrosis of the mesenteric lymph nodes and spleen. All 5 fetuses tested negative for IgG to E risticii, although 3 had low IgM titer to E risticii. The remaining 5 infected ponies had normal parturition. Presuckle IFA titer to E risticii was measured in 4 of the term foals, and results for 3 were positive. Two foals from infected ponies were monitored for 6 months and daily gain in body weight was comparable to that of a control foal. None of the control ponies became ill or seroconverted during the clinical illness phase, and none aborted throughout gestation Two control ponies seroconverted to E risticii 6 weeks before parturition. Results of this study indicate that E ristcii is a primary abortifacient under experimental conditions.

Correlations between the Myers-Briggs Type Indicator and the Neo Personality Inventory facets.

Using data obtained from 48 male and 161 female undergraduate students in psychology, correlations between scores on the scales of the Myers-Briggs Type Indicator and the facets of the Neuroticism, Extraversion, and Openness domains of the NEO Personality Inventory were low to moderate.

The relationship between psychometric intelligence and the five-factor model of personality in a rehabilitation sample.

WAIS-R and NEO Personality Inventory (NEO-PI) scores obtained from 85 rehabilitation clients of the Evaluation and Development Center of Southern Illinois University's Rehabilitation Institute were utilized to examine the relationship between psychometric intelligence and personality. Correlational analyses revealed that the NEO-PI Openness domain and its six facets significantly correlated with WAIS-R FSIQ, VIQ, PIQ, and 9 of the 11 subtests. Multiple regression analyses showed that the five NEO-PI domains accounted for significant proportions of WAIS-R, FSIQ, VIQ, and PIQ score variance. The NEO-PI Openness domain was found to be the best predictor of WAIS-R FSIQ, VIQ, and PIQ scores. The study concludes with a discussion of the meaning and implications of the findings and suggestions for future research.

Rickettsiae and Borrelia burgdorferi in ixodid ticks.

Nymphs and adults of hard-bodied ticks were collected in Connecticut and tested by direct and indirect immunofluorescence staining methods for rickettsiae and Borrelia burgdorferi. Of the 609 Ixodes dammini ticks examined, 59 (9.7%) harbored rickettsialike microorganisms in hemocytes (blood cells). These bacteria reacted with fluorescein-conjugated antiserum to Ehrlichia canis, the etiologic agent of with fluorescein-conjugated antiserum to Ehrlichia canis, the etiologic agent of canine ehrlichiosis. Prevalence of infection ranged from 6.8 to 12.7% for males and females, respectively. Although the specific identities of the hemocytic rickettsialike organisms are unknown, they share antigens with ehrlichiae. Electron microscopy revealed rickettsiae in ovarian tissues of I. dammini that also had infected hemocytes. Rickettsialike organisms were also observed in the hemocytes of 5 (6.9%) of 73 Dermacentor variabilis ticks. In analyses for B. burgdorferi, 146 (23.7%) of 617 I. dammini ticks harbored these spirochetes in midguts. Hemocytic rickettsialike microorganisms coexisted with B. burgdorferi in 36 (6.7%) of the 537 nymphs and adults of I. dammini examined. I. dammini, with its broad host range, has the potential to acquire multiple microorganisms.

Hemophagocytic syndrome: a cause of pancytopenia in human ehrlichiosis.

A 67-year-old white man with human ehrlichiosis infection complicated by pancytopenia, hemophagocytic syndrome, disseminated intravascular coagulopathy and septic shock is presented. The patient had been on a three-week camping trip to California, Colorado, Utah, and New Mexico. The diagnosis of human ehrlichiosis was confirmed by sixteen-fold rise in antibody titer to Ehrlichia canis, and supported by the characteristic cytoplasmic inclusions. Human ehrlichiosis should be considered in the differential diagnosis in patients with fever and cytopenia associated with hemophagocytosis. Pancytopenia associated with ehrlichiosis is transient; however, it may be severe, and appears to be associated with destruction of normal blood elements.

An overview of research on ehrlichiosis.

Ehrlichiosis is a disease caused by a group of rickettsiae, known as ehrlichiae, which parasitize circulating leukocytes of man and a variety of domestic and wild animals. A characteristic morphologic feature of ehrlichiae is their occurrence in membrane-bound vacuoles in the cytoplasm of leukocytes, forming inclusions that contain variable numbers of organisms. The tick is the apparent vector of ehrlichiae, but such evidence is not available for all species.

Isolation of a previously undescribed rickettsia from an aborted bovine fetus.

A previously undescribed obligate intracellular bacterium was isolated from an aborted bovine fetus. The organism was resistant to penicillin, replicated within cytoplasmic vacuoles, exhibited structural characteristics compatible with the rickettsias, and shared antigenic determinants with Cowdria ruminantium.

Recrudescence of Entopolypoides macaci Mayer, 1933 (Babesiidae) infection secondary to stress in long-tailed macaques (Macaca fascicularis).

Parasites were found in red blood cells of two long-tailed macaques (Macaca fascicularis) imported from Indonesia and housed in the Washington Regional Primate Research Center breeding colony for 7 years or longer. Both macaques developed parasitemias secondary to stress (type D retrovirus in one case and severe trauma in the other). Entopolypoides macaci (Babesiidae) was diagnosed on the basis of morphology from peripheral blood smears stained with Wright's stain. Antibodies against Babesia sp. were detected by immunofluorescence assay (IFA) from one infected macaque, which showed antibody cross-reactions (high titer) to B. bigemina, B. bovis, B. canis, and (low titers) to Plasmodium falciparum. Five feral long-tailed macaques that had been imported recently from the same country had no detectable antibodies. This is the first report of IFA as an aid to diagnose E. macaci in nonhuman primates.

Canine ehrlichiosis in Connecticut.

The first case of canine ehrlichiosis in Connecticut is reported. A female Brittany spaniel from Milford presented with lethargy, anorexia, fever, petechiae, splenomegaly, thrombocytopenia, anemia, elevated serum alkaline phosphatase, lymphopenia, and hypoalbuminemia. Serologic analysis revealed antibodies to Ehrlichia canis (titer, 1:2,560). This documents a more northern geographic distribution in the United States for this infectious agent than had previously been suspected.

Monthly prevalence (in 1986) of antibody titers against equine monocytic ehrlichiosis in apparently healthy horses in Illinois.

The seroprevalence and seasonal trend of antibody titers against equine monocytic ehrlichiosis (Potomac horse fever) were determined in apparently healthy horses in selected areas of Illinois in 1986. Sera from 1,367 horses (6 months to 29 years old) were evaluated for the presence of antibodies against Ehrlichia risticii with indirect immunofluorescence. The majority (88%) of the horses were Thoroughbred or Standardbred racehorses. The number of horses with antibodies against E risticii was 229/1,367 (16.75%). The titers in these horses ranged from 1:10 to 1:640. As the year progressed, the number of seropositive horses (titers greater than or equal to 1:10) and the magnitude of the titers increased significantly, both reaching a maximum in July and August, respectively (P less than 0.05). A relationship between seropositivity and gender was not detected. In the year prior to sampling, 56.8% of the seropositive horses had not been ill, whereas 0.8% had diarrhea, an episode of acute abdominal pain, or laminitis. It was concluded that a large number of horses in Illinois are exposed to E risticii, that maximal exposure occurs in July, and that the most common form of the disease in Illinois is not associated with clinical signs.

Susceptibility of cats to infection with Ehrlichia risticii, causative agent of equine monocytic ehrlichiosis.

Eight adult cats were inoculated IV (n = 6) or SC (n = 2) with Ehrlichia risticii-infected P388D1 (continuous murine macrophage) cells or with E risticii released from P388D1 cells. Three additional cats were inoculated with organism-free P388D1 cultured monocytes, and 1 cat, which served as a medium control was inoculated with balanced salt solution. Clinical signs of illness were observed in the IV inoculated cats from which E risticii was isolated. One cat developed intermittent diarrhea between postinoculation days (PID) 8 and 18, and the other cat developed lymphadenopathy, acute depression, and anorexia between PID 20 and 24. Ehrlichia risticii was isolated in cultures from 2 of 6 IV inoculated cats on PID 6, 10, and 17. Both cats were inoculated with E risticii released from the P388D1 cells. Ehrlichia risticii was not isolated from SC inoculated cats or from control cats. All 8 cats inoculated with E risticii seroconverted between PID 10 and 23. A pony inoculated with E risticii isolated from 1 of the inoculated cats developed clinical signs of equine monocytic ehrlichiosis including fever, anorexia, depression, and mild colic. Ehrlichia risticii was isolated from the blood of this pony on PID 7, 9, 11, and 16.

Susceptibility of dogs to infection with Ehrlichia risticii, causative agent of equine monocytic ehrlichiosis (Potomac horse fever).

Adult dogs 1 to 5 were inoculated IV and/or SC with 3, 5, or 6 ml of a suspension containing 1.2 x 10(4) Ehrlichia risticii-infected cells (derived from primary canine monocyte cell cultures)/ml. Dogs 6 to 8 were inoculated IV and/or SC with 3 or 6 ml of 1.2 x 10(5) organism-free cultured canine monocytes/ml. Ehrlichia risticii was isolated in cultures from inoculated dogs 3, 4, and 5 on postinoculation days (PID) 10 to 16, but not from dogs 6 to 8. Dogs inoculated with E risticii seroconverted between PID 6 and 12. Clinical signs of illness were not observed in these 5 E risticii-inoculated dogs. A pony, inoculated with E risticii isolated from inoculated dog 5, developed clinical signs of equine monocytic ehrlichiosis, including fever, anorexia, depression, and diarrhea, and E risticii was isolated from the pony's blood. This E risticii isolate was then inoculated into susceptible dog 9, and E risticii was repeatedly isolated from dog 9 during PID 6 to 17. Dogs were susceptible to infection with E risticii and may serve as a reservoir of the organism in the field.

Unexplained febrile illnesses after exposure to ticks. Infection with an Ehrlichia?

The Ehrlichia are tick-borne rickettsial organisms that cause disease in animals throughout the world but that have been previously recognized as human pathogens only in Asia. We have identified six patients with serological evidence of recent infection with an Ehrlichia: a fourfold or greater rise or fall in titer to Ehrlichia canis. All of the patients reported recent tick bites. Rigors, myalgia, headache, nausea, and anorexia were each reported by five patients. Fever was present in all patients and was accompanied by relative bradycardia and leukopenia in five patients, thrombocytopenia and abnormal liver function test results in four, and anemia in three. Five of the six patients were treated with tetracycline hydrochloride, and all recovered. Infection with Ehrlichia should be considered in patients with unexplained febrile illnesses after tick exposure.

Diagnosis of equine monocytic ehrlichiosis (Potomac horse fever) by indirect immunofluorescence.

The recent establishment of a system for the continuous in vitro propagation of Ehrlichia risticii, the causative agent of equine monocytic ehrlichiosis (EME; synonym, Potomac horse fever), has facilitated the development of an indirect fluorescent antibody test for the diagnosis of this disease under laboratory and field conditions. The field diagnostic application of the test has aided in the recognition of the disease in 16 states of the United States and in 1 province of Canada. A limited epidemiologic study conducted between January and September 1985, in an area where the disease is known to be enzootic, revealed that conversion from seronegative to seropositive status is not always accompanied by clinical manifestations of the disease. Confirmatory findings in experimentally inoculated horses suggest the existence of clinically undetectable infections.