Tissue localization and CD8 accessory molecule expression of T gamma delta cells in humans.

In this study, we used TCR isotype-specific antibodies to examine the frequency, phenotype, and histologic localization pattern of T gamma delta cells in humans. The TCR delta 1+ cells comprised an average of 15% of the splenic CD3+ cells and 7% of circulating T cells. The T gamma delta cells in these human tissues, like their avian counterparts, were often not "double-negative" for the CD4 and CD8 accessory molecules. Approximately 50% of the splenic delta+ cells expressed CD8, and 30% of the delta+ cells in blood were CD8+. T cells of both gamma delta and alpha beta TCR isotypes were exceedingly rare in the skin. The T gamma delta cells exhibited preferential homing to the sinusoidal areas (red pulp) of the spleen and into the epithelial layer of the intestine in humans, as had been previously noted in chickens. Although 80% of the T gamma delta cells in the human intestinal mucosa were localized in the epithelial layer, these cells represented only 5 to 10% of all the CD3+ T cells in this microenvironment. We conclude that T gamma delta cells represent a sizeable subpopulation of the T cells in human peripheral tissues. The phylogenetic conservation of the CD8 expression by peripheral T gamma delta cells and of their preferential homing pattern suggests a special role in bodily defense for this T cell subpopulation.

Human lamina propria lymphocytes bear homing receptors and bind selectively to mucosal lymphoid high endothelium.

It has been hypothesized that the selective recognition of tissue-specific endothelial cell molecules helps determine the in vivo distribution of lymphoid effector cells by controlling the extravasation of their circulating precursors. Here we report (a) immunofluorescence studies of the cell surface phenotype of human lamina propria lymphocytes (LPL), including staining with monoclonal antibody Hermes-1, which defines a 90-kDa lymphocyte surface glycoprotein involved in recognition of high endothelial venules (HEV); and (b) functional analyses of the ability of LPL to bind to HEV in frozen sections of mucosal lymphoid tissues (appendix or Peyer's patch) vs. peripheral lymph nodes. Essentially all LPL bear the Hermes-1 antigen, over 90% at levels comparable to those of circulating PBL. As a population, LPL display a quantitative preference for adherence to mucosal HEV, binding 0.8-1.5 times as well as PBL to mucosal HEV, but only 0.1-0.5 times as well to HEV in peripheral lymph nodes. Of particular interest was the behavior of the lymphoblast fraction, which typically constituted 3-7% of LPL. These cells, defined by size, consisted of a mixture of T cells and surface IgA+ blasts. One hundred percent were Hermes-1 bright, and they bound 4-8 times more efficiently to mucosal HEV than PBL while failing to bind detectably to lymph node HEV. LPL binding to mucosal HEV involves the gp90 Hermes, since the monoclonal anti-gp90 antibody, Hermes-3, and a polyclonal anti-gp90 antiserum inhibit the binding of small LPL and of LP blasts. The remarkable efficiency and specificity of binding by LP blasts may reflect retention of homing properties of the blood-borne precursors of these blasts and is discussed in relation to the capacity of immunoblasts in mesenteric nodes and in thoracic duct lymph to traffic selectively to mucosal lymphoid and extralymphoid sites. The demonstration of organ-specific endothelial cell recognition by LP lymphoblasts provides considerable support for the concept that selective interactions with endothelium play an important role in directing the distribution of activated lymphocyte subsets in vivo.

Immunohistochemical distribution of hepatic fatty acid-binding protein in rat and human alimentary tract.

Tissues from rat and human alimentary tract were immunostained with rabbit antibodies to fatty acid-binding protein (FABP) isolated from rat liver, since the precise immunohistochemical localization of the protein in gut has not been determined. The results obtained indicated that FABP immunoreactivity was found almost exclusively in intestinal absorptive cells, the sole exception being its presence in the cytoplasm of a few goblet cells. In small bowel, FABP-positive cells were most often found in the upper and middle segments, and less frequently in the lower to terminal portion. Immunoreactive cells were also found in large bowel of rat and human, but with differing patterns of distribution. In rat, positive cells were found mainly in the lower portion of the large intestine, whereas in human positive cells were present in all portions. Immunoreactive cells were detected in rat and human cecum, in the upper half of human rectum, and in human vermiform appendix. No such cells were found in esophageal and nonmetaplastic gastric mucosa or in pancreatic tissue, whereas they were present in great numbers in metaplastic gastric mucosa. The results of this study therefore suggest that FABP is a useful marker for research into the physiology or pathology of absorptive cells in the gastrointestinal tracts of both species.

Appendicitis revisited: a comparative study of Malawian and English appendices.

The incidence of appendicitis shows a marked variation between populations which has been attributed to dietary differences. Neural mechanisms and serotonin discharge from subepithelial neurosecretory cells have been previously implicated in pain referable to the appendix and appendicitis. Forty consecutive appendicectomy specimens from Malawi were studied by staining with haematoxylin and eosin, an alcian blue - PAS diastase sequence coupled with lead haematoxylin (PbH) and immunohistology for serotonin and NSE. The findings were compared with those in appendices removed at the Middlesex Hospital, London, to see if there were any differences between a population with a low risk of appendicitis (Malawi) and a high risk population (England). Acute transmural appendicitis was seen in fewer appendices from Malawi (27.5 per cent) than in English appendices (58 per cent). Subepithelial neurosecretory cells identified with PbH were present in 20 per cent of appendices from Malawi and 69 per cent of English appendices. These cells in both series showed immunohistochemical staining for serotonin. Nerve hyperplasia identified by staining for NSE in the appendix was present in 17.5 per cent and 81 per cent of non-inflamed appendices from Malawi and England respectively. Appearance of subepithelial neurosecretory cells and hyperplasia appear to be concomitants of an increased risk of appendicitis. Neural mechanisms may participate in adapting to a low residue diet and in some cases may generate appendicitis.

Neurogenous hyperplasia leading to appendiceal obliteration: an immunohistochemical study of 237 cases.

A series of 237 appendices was studied immunohistochemically for neurogenous hyperplasia. This was observed in 195 cases. It was possible to trace a continuum from appendices with intact lumens, featuring intramucosal neurogenous hyperplasia often with co-existent submucosal and muscular nerve growth, to obliterated specimens whose axial portions were composed of varying proportions of nerve tangles and fibrous tissue. Predominantly fibrotic specimens were considered as end-stages of this process. Stromal, argyrophilic cells lying amidst the nerve elements were prominent in the early, non-obliterated cases; their number decreased in the obliterated nerve rich specimens and such cells became inapparent in the late fibrotic stage. Repeated minimal subclinical attacks of inflammation are thought to trigger this lesion.

Subacute sclerosing panencephalitis: detection of measles virus RNA in appendix lymphoid tissue before clinical signs.

An appendix removed 15 days before onset of symptoms of subacute sclerosing panencephalitis was examined retrospectively for measles virus ribonucleic acid (RNA). Tissue sections hybridised in situ to a cloned measles virus probe of deoxyribonucleic acid specific for nucleocapsid protein showed that many cells of the lymphoid tissue contained measles virus RNA. In contrast, only a few infected lymphoid cells were detected in three out of six seropositive controls and none in three seronegative infants. A widespread chronic viral infection of the immune system, established after measles, may promote or even initiate nerve cell infection in subacute sclerosing panencephalitis.

S-100 protein in carcinoid tumours of appendix.

A series of 12 carcinoid tumours of the appendix were examined with regard to S-100 protein immunoreactivity. All tumours were both argentaffin and argyrophil, and displayed immunoreactivity after application of a monoclonal antibody against serotonin. The S-100 protein immunoreactivity appeared in 11 of the 12 tumours, preferably in cells presumably of Schwann cell origin with long slender processes localized at the periphery of the carcinoid tumour buds. Immunoreactive cells with cytoplasmic processes were also seen extending between individual tumour cell in the tumour aggregates. In a few tumours S-100 immunoreactivity occurred in the cytoplasm of tumour cells with or without cytoplasmic extensions. The presence of S-100 protein immunoreactive cells, apparently as an integral component, and its shape and distribution indicate that the peripheral nervous system (PNS) is histogenetically involved in the development of carcinoid tumours of the appendix.

The distribution of cells expressing a natural killer cell marker (HNK-1) in normal human lymphoid organs and malignant lymphomas.

A murine monoclonal antibody, HNK-1, is known to react with some human leukocytes including all natural killer (NK) cells in peripheral blood. The distribution of cells reacting with this antibody (HNK-1+ cell) was studied in human peripheral lymphoid organs, consisting of five lymph nodes, two specimens of gastric mucosa with lymphoid tissue, two tonsils, one appendix, and two thymuses. Fourteen cases of malignant lymphoma (ML) were also examined. For the demonstration of HNK-1+ cells, the peroxidase-antiperoxidase (PAP) bridge method was applied to cryostat sections of these specimens. It was found that in normal lymphoid organs most HNK-1+ cells were located in lymph follicles, especially in germinal centers, and some were found in 'mixed' regions which indicate outsides of both the follicles and T-zones. Amongst the ML, large clusters of HNK-1+ cells were observed only in two cases of follicular lymphoma, although a few scattered HNK-1+ cells were noted in other ML, including five diffuse B-cell lymphomas, six T-cell lymphomas and one null cell lymphoma. The possible significance of these findings is discussed.

Effect of various pharmacological agonists on the rat caecum-appendix preparation: a preliminary study.

A preliminary study with various pharmacological agents revealed the presence of contractile muscarinic and H1-histamine receptors as well as inhibitory alpha- and beta-adrenoceptors and purinoceptors in rat caecum-appendix. Histamine also produced indirect actions mediated through the release of catecholamines. 5-Hydroxytryptamine produced variable response, the contractile response was mediated through 5-HT receptors and the relaxant response through the release of catecholamines.

Liquid chromatographic estimation of doxycycline in human tissues.

A rapid, sensitive and specific liquid chromatographic method is described for the determination of doxycycline in human tissues. The procedure involves mechanical homogenization of tissue samples in hydrochloric acid followed by extraction of the drug and an internal standard into ethyl acetate. Chromatographic separation is performed on a reversed phase column and allows quantitation of tissue levels as low as 0.68 nmol/g using a 200-400 mg sample. Application of the assay to tissue samples obtained from 36 patients confirmed the excellent penetration of doxycycline in organs. The method supersedes the classical microbiological assays in specificity and speed.

Enkephalins in large bowel malignancy and in acute appendicitis.

Leucine and methionine enkephalins were measured by biological assay in normal colon, adenocarcinoma of the colon, carcinoma of the caecum, and in normal and inflamed appendix. Methionine enkephalin levels in both the adenocarcinomas and inflamed appendices were significantly higher than in normal controls. No significant change occurred in leucine enkephalin levels. The caecal tumours were anaplastic and contained no demonstrable opioid activity.