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J Longley

Publications and source records attributed to J Longley.

29 records · Page 2Linked to original sources
PubMed1989

Molecular cloning of CD1a (T6), a human epidermal dendritic cell marker related to class I MHC molecules.

To investigate the structure, function, and control of CD1a, we have cloned a 1.6-kbp cDNA which encodes the expressed CD1a protein and includes untranslated 5' and 3' sequences and the poly-A tail. As the protein recognized by the monoclonal antibody OKT6, CD1a is a useful marker for Langerhans cells (LC). CD1a is found on these cells and on thymocytes, suggesting an important immunologic role for this molecule. We constructed a cDNA library in lambda gt10 using mRNA from MOLT-4, a cell line that expresses the CD1a surface antigen. We then screened the library with an oligonucleotide synthesized according to a known partial sequence for CD1a, and subcloned the cDNA and its restriction fragments into pGEM for sequencing and probe production. Based on this sequence the CD1a protein is predicted to consist of three extracellular domains (alpha 1-3), a hydrophobic transmembrane region, and a cytoplasmic tail. DNA 5' to the alpha 1 region may undergo alternative exon splicing. There is high sequence identity between the beta-2 microglobulin binding region of MHC I molecules and CD1a. The secondary structure predicted for CD1a is very similar to the actual structure of HLA-A2, a classical MHC I molecule. The similarity includes the beta pleated sheets and alpha helices which form the antigen binding groove of the alpha-1 and alpha-2 domains. The homology predicted between CD1a and HLA-A2 in these regions appears to exist on the level of secondary structure despite low primary nucleotide and amino acid sequence identity. The structural data and probes we have developed should facilitate studies of the function of CD1a as well as novel investigations of LC.

Amino Acid Sequence↗
PubMed1989

In situ transcription and detection of CD1a mRNA in epidermal cells: an alternative to standard in situ hybridization techniques.

To develop methods for the investigation of mRNA transcription in rare epidermal cells, we used in situ transcription to study CD1a mRNA in isolated CD1a positive cells. We chose to study this Langerhans cell marker because it is not known which epidermal cells actually produce the CD1a protein and because there is evidence that CD1a mRNA is alternately spliced, a situation which could lead to truncated or alternate protein products in CD1a surface protein negative cells. Disaggregated epidermal cells were resolved into CD1a surface protein positive and negative groups by fluorescence activated cell sorting and cytocentrifuged onto glass slides. A synthetic 52 base, CD1a specific anti-sense oligomer was hybridized to CD1a gene transcripts in these cells, and radiolabeled cDNA synthesized in situ on the oligomerprimed CD1a transcripts. The labeled cDNA fragments were visualized in the cells of origin by autoradiography, and grains per cell were counted. Sixty-eight percent of cells expressing CD1a protein contained CD1a mRNA, as evidenced by grain counts more than two standard deviations above the mean value for similar cells carried through the same procedure with a control oligomer, or the mean value of CD1a surface protein negative cells treated with the CD1a specific oligomer. Thus, it seems likely that the CD1a protein positive epidermal cells use CD1a mRNA to make their own CD1a protein, and that a truncated or masked CD1a protein is not made by CD1a negative neonatal foreskin epidermal cells. In our hands, in situ transcription is simpler and faster than standard methods of in situ hybridization with prelabeled cDNA or RNA probes. Furthermore, it can be applied to the detection of any message of known sequence. The combination of cell sorting and in situ transcription can be used to localize and quantify the expression of specific mRNA by individual cells, allowing the study of rare and difficult-to-obtain cells.

Antigens, CD1↗
PubMed1987

Clinical and histologic features of pityriasis lichenoides et varioliformis acuta in children.

Pityriasis lichenoides et varioliformis acuta (PLEVA) is commonly thought of as a disease of young adults, yet we identified five cases, involving patients who were 3, 5, 6, 8, and 11 years of age, among 13,000 consecutive specimens submitted to a general dermatopathology laboratory during a 15-week period. The clinical and histologic features of PLEVA in our cases were similar to those reported for adults, except that no lesions were observed on the scalp or mucous membranes of children. A high index of suspicion and biopsy specimens of suspected lesions are often needed to differentiate PLEVA from other papular and crusted eruptions seen in the pediatric age group. These include reactions to arthropods, Gianotti-Crosti syndrome, varicella, and erythema multiforme. Histologically, papular eczema and pityriasis rosea may be misdiagnosed as PLEVA.

Acute Disease↗
PubMed1985

The role of interleukin-2 (IL-2) in the specific unresponsiveness of lepromatous leprosy to Mycobacterium leprae: studies in vitro and in vivo.

The role of IL-2 in the immunological deficiency of lepromatous leprosy patients towards Mycobacterium leprae have been studied further. After initial stimulation with M. leprae + IL-2, lepromatous lymphocytes could be restimulated with M. leprae alone. The specificity of the responses obtained varied. Some patients gave a stronger response to BCG as compared to M. leprae, while in others a stronger response to M. leprae as compared to BCG was obtained. Studies of the composition of lymphocytes in dermal infiltrates subsequent to injection of killed M. leprae revealed that in both tuberculoid and lepromatous patients, early accumulation of cell staining for both IL-2 receptor and IL-2 were seen. However, with time IL-2 receptor and IL-2 staining lymphocytes diminished in lepromatous infiltrates, while these were maintained in tuberculoid lesions.

Humans↗
PubMed1985

In vivo responses to Mycobacterium leprae: antigen presentation, interleukin-2 production, and immune cell phenotypes in naturally occurring leprosy lesions.

To investigate the immune defect in lepromatous leprosy we studied immune cell phenotypes, lymphocyte activation states, and interleukin-2 (IL-2) production in naturally occurring leprosy skin lesions. Mouse hybridoma monoclonal antibodies reacting with the IL-2 receptor (anti-Tac), unbound IL-2 (DMS-1), antigen-presenting Langerhans' cells (OKT6) and the OKT4-Leu3 and OKT8 T-lymphocyte subpopulations were used with indirect horseradish peroxidase and alkaline phosphatase techniques on frozen biopsy sections. The percentage of Tac+ lymphocytes and the number of OKT6+ cells in the epidermis and dermal granuloma were significantly correlated in naturally occurring lesions (correlation coefficient 0.79) and were higher in tuberculoid than in lepromatous lesions. Leu3 antigen was expressed by 70-90% of Tac+ cells in tuberculoid lesions. Although the percentage of cells producing IL-2 was low in lesions of both lepromatous and tuberculoid patients, it was about 15 times greater in tuberculoid than in lepromatous lesions (0.032 +/- 0.037 tuberculoid vs 0.0019 +/- 0.023 lepromatous). There was an association between the number of OKT6+ cells and the percentage of IL-2-producing cells, but the association was weaker than that of OKT6+ cells and the percentage of IL-2 receptor-bearing cells (r = 0.2), implying that IL-2 production is not an intervening variable in the latter association. The absolute number of OKT4-Leu3+ lymphocytes was significantly different in different clinical leprosy groups and was positively correlated with host resistance (mean OKT4-Leu3+ cells/mm2 in 6 micron sections; 1412 +/- 288 tuberculoid, 400 +/- 93 borderline lepromatous, 200 +/- 100 polar lepromatous; r = 0.95). Absolute numbers of OKT8+ cells/mm2 in lesions were not significantly different. We conclude that there is a relative paucity of OKT4-Leu3+ cells as well as IL-2-producing cells at the local level in lepromatous leprosy lesions. Possible functional relationships between these findings and the failure of macrophage activation and destruction of Mycobacterium leprae in lepromatous leprosy are discussed.

Adolescent↗
PubMed1976

Assay of thalassaemic messenger RNA in the wheat germ system.

Messenger RNA(mRNA) has been prepared from reticulocytes obtained from patients with different types of thalassaemia and assayed in the wheat germ system. Since normal human reticulocyte mRNA directs the synthesis of equal numbers of alpha- and beta-globin chains in this system it offers a rapid and simple technique for assaying mRNA in the thalassaemic disorders. In mRNA from beta+ thalassaemics the deficiency of beta-globin synthesis mirrored that observed in intact reticulocytes while that prepared from patients wiht haemoglobin H disease gave alpha/beta globin chain production ratios which showed consistently greater imbalance than was found in reticulocytes. Messenger RNA prepared from haemoglobin E-beta0 thalassaemics from Thailand directed no detectable beta-chain synthesis while that prepared from a betaO thalassaemic from Ferrara synthesized a fraction with the chromatographic characteristics of beta-globin chains.

Globins↗