Ocular molecules and cells that regulate immune responses in situ

Regulation of T cell-dependent immune responses is mediated in part by bone marrow-derived antigen presenting cells (APC) that (a) process and present antigens which engage the T cell receptor and (b) secrete cytokines that influence the threshold of T cell activation. The anterior chamber of the eye is lined by the corneal endothelium (which rests on a stroma and epithelium that is devoid of class II MHC + APC) and iris/ciliary body (which contain significant numbers of bone marrow-derived cells, one third of which are class II MHC +). When tested in vitro, these potential APCs fail to present antigens in a form that activates T cells. Moreover, iris/ciliary body cells actually suppress activation of T cells exposed to antigens on conventional APC. In addition, aqueous humor under normal circumstances contains factors (one of which is TGF_B) that are potent inhibitors of antigen-driven T cell activation, but spare other aspects of T cell function. Evidence suggests that the bone marrow-derived cells in iris/ciliary body are the source of this factor. Thus, the anterior chamber contains powerful forces that can prevent induction and can suppress expression of T cell mediated immunity. It is proposed that these forces are responsible for immunologic privilege and anterior chamber associated immune deviation, and for suppressing pathologic proliferation and inflammation in the anterior segment of the eye.     

Use of polymerase chain reaction for rapid diagnosis of tuberculosis.

A DNA amplification assay using the polymerase chain reaction technique designed for the rapid identification of Mycobacterium bovis organisms was used to test 211 human mycobacterial isolates and 177 clinical specimens previously submitted for routine mycobacterial culture. The procedures described could be used by routine or specialist laboratories for identification of M. tuberculosis complex organisms in 4 h and/or as a rapid screening method for the direct detection of M. tuberculosis complex organisms in specimens.     

Competition-based cellular peptide binding assays for 13 prevalent HLA class I alleles using fluorescein-labeled synthetic peptides

We report the development, validation, and application of competition-based peptide binding assays for 13 prevalent human leukocyte antigen (HLA) class I alleles. The assays are based on peptide binding to HLA molecules on living cells carrying the particular allele. Competition for binding between the test peptide of interest and a fluorescein-labeled HLA class I binding peptide is used as read out. The use of cell membrane-bound HLA class I molecules circumvents the need for laborious biochemical purification of these molecules in soluble form. Previously, we have applied this principle for HLA-A2 and HLA-A3. We now describe the assays for HLA-A1, HLA-A11, HLA-A24, HLA-A68, HLA-B7, HLA-B8, HLA-B14, HLA-B35, HLA-B60, HLA-B61, and HLA-B62. Together with HLA-A2 and HLA-A3, these alleles cover more than 95% of the Caucasian population. Several allele-specific parameters were determined for each assay. Using these assays, we identified novel HLA class I high-affinity binding peptides from HIVpol, p53, PRAME, and minor histocompatibility antigen HA-1. Thus these convenient and accurate peptide-binding assays will be useful for the identification of putative cytotoxic T lymphocyte epitopes presented on a diverse array of HLA class I molecules.     

Practice effects with the NIMH AIDS abbreviated neuropsychological battery.

The degree of practice effects with the Brief NIMH Neuropsychological Battery for HIV Infection and AIDS is reported using a 7-10 day test-retest interval. The patient groups were asymptomatic and symptomatic of HIV while the control group was made up of "at risk" volunteers. Statistically significant practice effects were obtained on the California Verbal Learning Test, the Paced Auditory Serial Addition Task and the Visual Search Test among the infected individuals. The controls subjects demonstrated statistically significant practice effects on all of the neuropsychological tests. The implications of these findings in prospective studies are discussed.     

Xanthogranulomatous pyelonephritis in childhood: Ultrasound and CT diagnosis

Four cases of diffuse xanthogranulomatous pyelonephritis (XPN) in young children are presented. In three patients the clinical picture was one of weight loss, anaemia and neutrophilia with a large renal mass. The fourth presented with haematuria. Ultrasound (US) and CT findings were almost identical in all four patients. US showed the affected kidney was massively enlarged but retained a reniform shape. Dilated fluid spaces containing calculi were present. CT confirmed the US findings and revealed peripheral enhancement without contrast excretion, with dilated calyceal spaces producing the bear paw sign. Extrarenal extension into abdominal wall and psoas muscle is typical and was well demonstrated by CT. The affected kidneys were non-functioning and nephrectomy was required. Typical US and CT features allow a confident diagnosis of XPN and appropriate early treatment.