"Ia-like" antigens on human T cells.

Human T lymphocytes have been tested for cell surface p. 28,33 "Ia-like" heteroantigen and DRw alloantigens. Small numbers (1--5%) of sheep (E) rosette or T antigen-positive, surface immunoglobulin-negative (E+, T+, smIg-) T cells were Ia+; these cells appeared to be restricted to the TG subset. Following activation by allogeneic lymphocytes or sperm, or by purified protein derivative of tuberculin (PPD), the proportion of positive T cells increased substantially. DRw typing indicated that Ia specificities on activated T cells were not acquired passively from the stimulator cells, suggesting therefore that either "selection" of a small DRw+ cell subset or derepression and/or exposure of DR locus gene products occurs during T cell activation.     

Glucocorticoid inhibition of antigen-evoked histamine release from human skin

Prednisolone causes a dose-related inhibition of antigen-evoked histamine release from IgE-sensitized human skin in vitro. The effective concentrations are of the same order as are achieved in plasma therapeutically.

Analysis of prednisolone inhibition shows that it acts on the second histamine release stage, antigen—antibody combination being unaffected.

In contrast with the traditional view, our results show that, at least in human skin, glucocorticoids can inhibit antigen-evoked histamine release.

     

Cell surface markers for human T and B lymphocytes

A series of 4 cell surface marker systems have been developed and applied to human thymus, tonsil and purified blood lymphocyte populations. Double fluorochrome and mixed fluorochrome-rosette tests were used to determine cellular specificity and interrelationship of cells bearing the different markers and the results confirmed by a variety of cell separation procedures. Anti-brain antisera were, after appropriate absorption, T cell-specific and identified the same population as that forming rosettes with sheep erythrocytes. This T cell population was quite distinct from those cells, presumably B lymphcytes, with cell surface immunoglobulin readily demonstrable by fluorescence. A small proportion of “lymphoid” cells (“null” cells) lacked all three markers. Heat-aggregated human IgG (AggHIgG) was also used as a presumptive B cell marker and the results indicate that although most B lymphocytes do bind AggHIgG, presumably via an Fc receptor, a small proportion of thymocytes and presumptive T cells in tonsils also appear to possess a similar receptor. Almost all of these cells in tonsil were in fact lymphoblasts, thus raising the possibility that an Fc receptor is exposed or expressed on T lymphocytes when these cells are activated.     

Chromosome mapping of cell membrane antigens expressed on activated B cells

Hybrids formed by fusion of either human acute lymphoblastic or chronic lymphocytic leukemia cells and the mouse myeloma P3.X63.Ag8/653 have been used to show that the expression of two cell surface antigens, Bp37 and p76, associated with B cell activation and detected by the monoclonal antibodies BB1 and BB2, respectively, segregate with human chromosomes 12 and 19, respectively. Another antigen expressed on activated B cells (p24) also maps to chromosome 12 (Katz et al., Eur. J. Immunol. 1984. 13: 1008) which is of interest in the light of the frequent involvement of this chromosome in certain B cell leukemias and lymphomas.     

Lymphocyte activation: I. Response of T and B lymphocytes to phytomitogens

The selectivity of phytomitogens for T (thymus derived/dependent) and B (`bursa-equivalent' dependent/derived) lymphocytes from the mouse spleen has been investigated. Responses of normal spleen cell cultures were compared with those of cultures of selected B cells. The latter were obtained from three sources (1) spleen cells of mice that had been thymectomized as adults, lethally irradiated and reconstituted with syngeneic bone marrow cells pretreated with anti-θ serum (2) spleen cells from congenitally athymic (`nude') mice and (3) spleen cells from normal mice treated with anti-θ serum plus guinea-pig complement prior to culture.

Using a variety of different culture conditions it was shown that B cells respond well to pokeweed mitogen, and poorly if at all to phytohaemagglutinin. Responsiveness to the latter mitogen in normal spleen cell cultures appears to be a property of T cells.

     

The nitric oxide pathway in pre-eclampsia: pathophysiological implications

Pre-eclampsia, one of the most significant health problems inhuman pregnancy, complicates 6-7% of all gestations and is theleading cause of fetal growth retardation, infant morbidityand mortality, premature birth and maternal death. Recent researchimplicates free radicals in the pathophysiology of pre-eclampsia.This review covers the biochemistry of nitric oxide (NO) andpossible interactions with other free radicals. Studies in therat show that pregnancy is associated with enhanced productionand responsiveness to NO in both reproductive tissues and bloodvessels. Rats infused with N^G-nitro-L-arginine methyl ester(L-NAME, a NO synthase inhibitor) have been used as an animalmodel of pre-eclampsia, and the effects of steroid hormoneson blood pressure in this model have been tested. Results suggestthat pre-eclampsia may be a state of NO deficiency. However,in humans there seem to be contradictions regarding the involvementof NO in maternal adaptation to pregnancy. It is suggested thatNO may be one of several systems that act in concert to maintaina symbiotic relationship between mother and fetus. However,the input of each system may be genetically determined.     

A concept-based retrieval system for thoracic radiology

Current digital information systems in radiology are insufficient to accommodate the retrieval needs of academicians. Significant efforts are required in retrieving clinical cases for teaching and research. We describe a prototype system that supports intelligent case retrieval based on a combined specification of patient demographics, radiologic findings, and pathologic diagnoses. The documents for these cases can be distributed among multiple heterogeneous data bases. The system features automatic indexing of radiology and pathology reports, a comprehensive lexicon for thoracic radiology, an interface to a hospital information system, radiology information system, and picture archiving and communication systems, and a graphical user interface for query formulation and results visualization. The prototype system was developed within the domain of thoracic radiology involving patients with lung cancer.