Isolation and purification of human large bowel mucosal lymphoid cells: effect of separation technique on functional characteristics

An Optimized and Validated Method for Isolation and Characterization of Lymphocytes from HIV+ Human Gut Biopsies

The gastrointestinal (GI) tract harbors most of the body's immune cells and is also a major HIV reservoir in ART-treated patients. To achieve a cure, most HIV-infected cells must be identified and eliminated. While obtaining gut biopsies is a relatively noninvasive method of sampling relevant tissue for monitoring HIV activity, immune cell isolation from these limited tissue samples has proven to be challenging. Enzymatic tissue digestion is required for maximal immune cell isolation from gut biopsies. However, these enzymatic digestions can also be detrimental for preservation of cellular surface markers that are required for accurate identification of various subsets of leukocytes. In this study, we describe an optimized protocol for isolation of lymphocytes from human gut biopsies. We also discuss our validation results, which show that compared with several other collagenase preparations, the use of CSLPA maintains high lymphocyte recovery while preserving the integrity of most cellular surface antigens that we tested. Importantly, chemokine receptors that are used to characterize various subsets of T cells, which are notorious for being digested during a typical enzymatic tissue digestion, are highly preserved using this protocol.

Impact of enzymatic tissue disintegration on the level of surface molecule expression and immune cell function

Immunological characterization of immune cells that reside in specific anatomic compartments often requires their isolation from the respective tissue on the basis of enzymatic tissue disintegration. Applying enzymatic digestion of primary splenocytes, we evaluated the impact of collagenase and dispase, two enzymes that are commonly used for the liberation of immune cells from tissues, on the detectability of 48 immunologically relevant surface molecules that are frequently used for flow cytometric identification, isolation, and characterization of immune cell subsets. Whereas collagenase treatment had only minor effects on surface expression of most molecules tested, dispase treatment considerably affected antibody-mediated detectability of the majority of surface markers in subsequent FACS analyses. This effect was long lasting and, in case of high-dose dispase treatment, evident for the majority of surface molecules even after 24 h of in vitro culture. Of note, high-dose dispase treatment not only affected surface expression of certain molecules but also impaired antigen-specific proliferation of CD4(+) and CD8(+) T cells. Together, our data indicate that enzymatic tissue disintegration can have profound effects on the expression of a variety of cell-surface molecules with direct consequences for phenotypic analysis, FACS- and MACS-based target cell isolation, and immune cell function in cell culture experiments.

Isolation of human intestinal mucosal mononuclear cells

The aim of this procedure is to obtain large numbers of isolated, viable, and functional mononuclear cells that are representative of the lymphoid population present in the mucosa of the human gastrointestinal tract under physiological and pathological conditions. The basic protocol is based on the use of surgically resected small and large bowel specimens, and consists of two basic stages: (1) a combination of chemical, enzymatic, and mechanical treatments to dissociate intestinal tissue and free the mononuclear cells from the surrounding interstitial framework; and (2) separation, isolation, and purification of viable mucosal lamina propria mononuclear cells from other cellular and amorphous components. The proportion of viable cells obtained can be increased by including extra separation steps using nylon wool columns or Percoll gradients, as described.

Development of a mucosal complex vaccine against oral Salmonella infection in mice

We examined the immunogenicity of a Salmonella enterica complex vaccine (CV), consisting of flagellin and polysome purified from serotype Typhimurium LT2. CV plus cholera toxin (CT), in three oral doses given at 7-day intervals, conferred complete protection on C57BL/6 mice against lethal oral infection with a wild-type strain. It elicited mucosal IgA > IgG2a > IgG1 and systemic IgG2a > IgG1 > IgA antibodies to flagellin and polysome, and delayed footpad response (DFR) to both antigens. In Peyer's patches (PPs) and lamina propria (LP), IgA was produced under a Th1-dominant environment; CD4+T cells from produced interleukin (IL)-2, interferon (IFN)-gamma, and IL-10 by stimulation with salmonella extract. On the same protocol, flagellin plus CT induced flagellin-specific mucosal and systemic IgA and IgG1 antibodies, CD4+T cells producing IL-10 and IFN-gamma in PPs and LP, and only minimal levels of flagellin-specific DFR. Polysome plus CT induced polysome-specific mucosal and systemic IgG2a in addition to IgG1 and IgA antibodies, CD4+T cells producing IFN-gamma and IL-2 in PPs and LP, and polysome-specific DFR. These two vaccines, however, conferred at most 50-60% survival rates. Our results suggest that polysomes in CV provide effective adjuvant activity for the induction of both mucosal and systemic Th1-biased responses toward flagellin.

Clonal expansion of lymphocytes from oral lichen planus lesions

Lymphocytes were extracted from 11 biopsy specimens of oral lichen planus (OLP) by collagenase digestion, and cell lines were expanded with repetitive cycles of stimulation (with phytohaemagglutinin) and rest in media supplemented with interleukin 2. Four OLP lines contained a majority of CD3+CD4-CD8+ cells, in six lines the CD4:CD8 ratio was between 1 and 2, and in one line the CD4:CD8 ratio was 5:1. Limiting dilution of nine lines at 0.3 and 1.0 cells/well resulted in viable wells (putative clones) with plating efficiencies ranging from 0.0 to 18.1 percent and 0.0 to 22.2 percent respectively. The majority of clones were CD3+CD4-CD8+alpha beta+gamma delta-, although three clones were CD3+CD4+CD8-alpha beta+gamma delta- and one clone was CD3+CD4-CD8- and expressed the gamma delta T cell receptor. T cell clones derived from lymphocytes extracted from OLP lesions may be generated and maintained in culture providing opportunity for their further phenotypic and functional characterisation. This strategy may facilitate the identification of a putative oral lichen planus-specific antigen and indicate the frequency of lichen planus-specific T cells within lesions of OLP.

Characterisation and quantification of mucosal cytokine that induces epithelial histocompatibility locus antigen-DR expression in inflammatory bowel disease

Epithelial histocompatibility locus antigen (HLA) class II expression was studied to evaluate its induction by mucosal mononuclear cells in inflammatory bowel disease and to characterise the responsible cytokine. Unstimulated cells of the HT-29 epithelial cell line did not produce class II molecules. After being stimulated with the mitogenic lectin phytohaemagglutinin mucosal mononuclear cells released a cytokine that induced epithelial HLA-DR expression. The cytokine had the physicochemical and immunological characteristics of interferon-gamma, and no additional cytokines were detected.

Cell recovery during segmental intestinal perfusion in healthy subjects and patients with Crohn's disease

The recovery of cells arising from small intestinal mucosa alone was studied during continuous perfusion of a closed segment of jejunum. The perfusion technique minimised the contamination of the perfused segment with, for example, proteolytic enzymes from pancreas, allowing recovery of viable cells. The use of hyaluronidase in the perfusion fluid increased the recovery of cells fivefold, the median recovery being 8 x 10(6) cells. The cells were analysed with monoclonal antibodies and flow cytometry. Nearly all cells (98-99%) recovered during perfusion of healthy control subjects and patients with Crohn's disease were epithelial cells. The jejunal cells expressed HLA-DR in similar proportions--around 30%--in patients and control subjects. The ratio between CD4+ and CD8+ lymphocytes was similar (0.2) in control subjects and patients with inactive Crohn's disease but decreased (0.03) in patients with active Crohn's disease in the ileum.

Tissue distribution and cytofluorometric analysis of oral mucosal T cells in the BALB/c mouse

The incidence and distribution of Thy-1.2+, Lyt-2.2+ and L3T4+ cells in the murine oral mucosa were investigated using qualitative and quantitative approaches. From immunostaining of frozen tissue sections, it appeared that the majority of oral T cells are located either in the epithelium or within the minor salivary gland network. The occurrence of Thy-1.2+, L3T4+ and Lyt-2.2+ cells at these sites points to two strategic lines of defence in the event of mucosal infections or aggression. A quantitative analysis of oral T-cell subsets was made possible by optimizing an enzymatic digestion procedure which preserves all three T-cell surface markers. Flow cytometric analysis of oral mucosal cells demonstrated that the helper phenotype is about twice as numerous as the cytotoxic/suppressor phenotype in the mucosa. Furthermore, in single cell suspensions, virtually all Thy-1+ cells were either L3T4+ or Lyt-2.2+ in the mucosa and in the spleen. From this frequency analysis and our previous studies, we conclude that T cells are a major component of the oral immune system, being 2-3 times as numerous as B cells or macrophages. Present data on the spatial distribution and characteristic ratio of T-cell subsets assess the basal activity of the local T-cell populations in healthy animals and lay the basis for comparative studies of both qualitative and quantitative variations occurring during mucosal infections or autoimmune reactions.

Isolation and functional characterization of chicken intestinal intra-epithelial lymphocytes showing natural killer cell activity against tumour target cells

Intestinal intra-epithelial lymphocytes (IEL) of SC or FP chickens were isolated and examined for their natural killer (NK)-cell activity against chicken tumour cell lines, LSCC-RP9 (RP9), LSCC-RP12 (RP12), MDCC-MSB-1 (MSB-1) and MDCC-CU36 (CU36). In general, IEL of satisfactory yield and of good viability were obtained with EDTA treatment of the gut tissues, followed by rapid passages of the resultant cells through nylon-wool columns and centrifugation on two-step Percoll density gradients (45% and 80%). In 4-hr and 16-hr 51Cr-release assays, the NK-cell activity of chicken IEL depended not only upon the type of target cells but also upon the incubation time and the host genetic background. RP9, MSB-1 and CU36 were susceptible to NK lysis by IEL and by spleen cells, while RP12 was resistant to lysis even after a prolonged incubation. In kinetic studies the cytotoxicity was detactable from 2 hr after incubation and progressively increased up to 16 or 18 hr. The IEL of SC chickens revealed significantly higher levels of NK-cell activity against RP9 than FP-strain chickens, whereas their splenic NK-cell activity was not significantly different. Against MSB-1 targets, however, IEL of SC and FP chickens showed similar levels of NK-cell activity while their spleens did not (being higher in FP). When tested in FP chickens, IEL NK-cell activity was inhibited by the addition of unlabelled homologous target cells. In general, NK-cell activity was higher in the jejunum and ileum than in the duodenum and caecum. Efforts to enrich IEL NK-effector cells by discontinuous Percoll gradients were not successful. The results of the present study show that IEL of chicken intestine contain effector cells that can mediate NK-cell activity against chicken tumour cells.

Bovine gut-associated lymphoid tissue--morphologic and functional studies. I. Isolation and characterization of leukocytes from the epithelium and lamina propria of bovine small intestine

A successful technique for the isolation of highly pure suspensions of viable leukocytes from the small intestine of cattle is described. Procedures ranging from mechanical mincing to enzymatic digestion of tissues were compared. The most reliable and reproducible procedure was the sequential treatment of tissues with dithiothreitol (DTT), ethylenediaminetetraacetic acid (EDTA) in calcium-magnesium-free salt solutions, and collagenase. Two populations of mucosal leukocytes were obtained from the small intestine. One population was derived from within the epithelium (intraepithelial leukocytes, IEL), the second from within the lamina propria (lamina propria leukocytes, LPL). At least 2 X 10(6) viable leukocytes were obtainable from each square centimeter of the intestinal mucosa from either the epithelium or lamina propria. Erythrocyte rosetting and immunofluorescence characterization with conventional antisera and monoclonal antibodies (MAB) demonstrated that IEL were predominantly T cells (60%), with relatively few B cells present (10%), while LPL contained relatively high numbers of B cells (28%) and a reasonable percentage of T cells (45%). Both cell populations proliferate in response to stimulation with T and B cell mitogens. Addition of the thiol compound, 2-mercaptoethanol (2-ME) strongly augmented the mitogenic response of both cell isolates. Human recombinant interleukin-2 (hr-IL-2) in the presence or absence of additional stimuli was found to be able to induce the proliferation of both cell types. These results demonstrate that functional leukocytes can be isolated from the small intestine of cattle, and that they can maintain their responsiveness to both T and B cell mitogens and to exogenous cloned IL-2.

Phagocytes in cell suspensions of human colon mucosa

Because little is known of the phagocytes of the human colon we enumerated these cells in mucosal suspensions and studied their phagocytic activity. Phagocyte rich suspensions were made by EDTA collagenase dissociation followed by elutriation centrifugation. Phagocytosis was evaluated by measuring cellular radioactivity after incubation of phagocytes with 3H-adenine labelled E coli ON2 and checked microscopically. Dissociation of normal mucosa from colorectal neoplasms yielded means of 1.9 X 10(6) eosinophils, 1.4 X 10(6) macrophages and 2 X 10(5) neutrophils per gram of mucosa. Visually normal mucosa of inflammatory states yielded 2.2 X 10(6) eosinophils, 2.3 X 10(6) macrophages and 7 X 10(5) neutrophils per gram of mucosa. Phagocyte rich suspensions of normal mucosa from tumour patients phagocytosed 21.8% of a pool of opsonised tritiated E coli ON2 and by microscopy 100% of mucosal neutrophils ingested bacteria, 83% of eosinophils were phagocytic, and 53% of macrophages contained bacteria. These results suggest that in the human colonic mucosa, the eosinophil is more abundant than the macrophage and the per cent of those cells exhibiting phagocytosis is intermediate between that of the macrophage and the neutrophil. Thus these three types of cells are actively phagocytic and share the potential for a major role in host defence against invasive enteric bacteria.

Definite spontaneous cell-mediated cytotoxicity and HNK-1 cells in the human large intestine

Spontaneous cell-mediated cytotoxicity (SCMC) and the marker of natural killer (NK) cells mediating SCMC of the human large intestine were studied. Lamina proprial lymphoid cells (LPL) were isolated by sequential dithiothreitol-EDTA-collagenase treatment of the gut specimen. SCMC was measured by the chromium release method. Target cells included P4788 in monolayer, a cell line derived from colon cancer, Chang cells in monolayer, and K562 in suspension. Target cells in monolayer including colon cancer cell line were chosen because they were thought to be more appropriate to assess SCMC for lymphoid cells in the solid organ. While lower compared to cytotoxicities (CT) by peripheral blood lymphoid cells (PBL), define CT were observed in LPL against all three targets. NK cells marker was studied both on LPL by an indirect fluorescent antibody method and on the gut tissue by indirect immunoperoxidase staining using anti HNK-1 monoclonal antibody which defines virtually all NK cells. HNK-1 positive (HNK-1 +) cells were identified in both methods. HNK-1 + cells were observed in the epithelium, lamina propria, and lymph follicle with or without germinal centers. These results clearly demonstrated the presence of SCMC and HNK-1 + cells in the human large bowel.

Responses of intraepithelial lymphocytes to T-cell mitogens: a comparison between murine and porcine responses

Intraepithelial lymphocytes (IEL) were isolated from the small intestine of pigs. They showed a strong blastogenic response to the T-cell mitogens phytohaemagglutinin A (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM); in contrast, mouse IEL responded weakly to these mitogens. The response of pig IEL was age-dependent, reaching adult levels by 9 weeks of age. Early weaning of pigs delayed the onset of this response. The effects of inflammatory mediators on the response of mouse IEL were also examined.

Isolation of intestinal mononuclear cells from colonoscopic biopsies for immunofluorescence analysis by flow cytometry

A method for isolating and characterizing intestinal lymphoid cells from colonoscopic biopsies is presented. Intraepithelial lymphocytes were separated from the lamina propria by incubation in edetic acid (EDTA) and lamina propria lymphoid cells isolated by incubation in collagenase followed by Ficoll-Hypaque density flotation. Quantitation of T lymphocyte helper (OKT4) and suppressor (OKT8) cells was performed using monoclonal antibodies to cell surface markers and analyzed on a flow cytometer. The isolation procedure yielded approximately 400,000 lamina propria cells and 100,000 intraepithelial cells per sample, with better than 90% viability. Surface marker analysis demonstrated significant differences in the ratios of helper to suppressor cells between the intraepithelial lymphocytes and the lamina propria lymphocytes. These demonstrate the feasibility of lymphoid cell isolation from colonoscopic biopsy specimens for surface marker analysis by flow cytofluorimetry. These techniques could prove important in the study of immune mechanisms in inflammatory bowel diseases.

Prostaglandins and the gastrointestinal mucosa: are they important in its function, disease, or treatment?

In 1971 interest in the role of prostaglandins in the gastrointestinal tract was stimulated by the publication of two hypotheses--that aspirin damaged the gastric mucosa by inhibiting prostaglandin synthesis (1) and that cholera toxin caused diarrhea by stimulating it (2). Subsequent research into the gastrointestinal actions of prostaglandins has been considerable and now impinges on clinical practice. This paper reviews the involvement of prostaglandins and related compounds in mucosal protection, in ulcer healing, in diarrhea, and in gastrointestinal inflammation, with particular reference to the growing body of human data.

Studies on lymphocyte subpopulations in human colonic biopsy specimens by colonoscopy

Lymphocytes, isolated by the enzymatic technique, from colonic mucosal specimens obtained from eight patients with ulcerative colitis (UC), two with ischemic colitis, two with antibiotic-associated colitis, and 15 controls by colonoscopic biopsy were used to examine T and B cells. In control biopsy specimens, the mononuclear cell yield averaged 3.6 +/- 0.3 (SEM) X 10(6)/g with a viability of 93 +/- 1%, while T and B cells expressed as a percentage of total lymphocyte counts were 65 +/- 1% and 15 +/- 1%, respectively. T and B cells in the ascending, transverse, and sigmoid colon and rectum did not present any differences. In involved tissue at the active stage of UC, the mononuclear cell yield averaged 11.4 +/- 2.1 X 10(6)/g, and T and B cells constituted 49 +/- 3% and 43 +/- 4%, respectively. After treatment for two months with salazosulfapyridine, mononuclear cell yields in five cases of UC were significantly reduced to an average of 3.9 +/- 0.8 X 10(6)/g as compared to the pretreatment level (P less than 0.01). The percentage of T cells was significantly increased from 48 +/- 2% to 62 +/- 2% (P less than 0.01), and that of B cells was significantly reduced from 39 +/- 2% to 27 +/- 3% (P less than 0.01). These results revealed a significant difference in the subpopulations of mucosal lymphocytes in the involved sites in the active stage of UC as compared to normal controls, suggesting that immunological abnormalities may be implicated in the etiology of this disease and that disease remission on salazosulfapyridine treatment is associated with a correction of the colonic lymphocyte abnormalities.

Isolation of intestinal mononuclear cells: factors released which affect lymphocyte viability and function

Whether toxic or immunomodulatory factors are released during the collagenase digestion phase of the isolation of mononuclear cells from human intestinal mucosa was investigated by assessing the effect of the collagenase supernatant on the viability and natural killer activity of normal peripheral blood mononuclear cells. Three hours' incubation in collagenase supernatant suppressed natural killer activity by 25 +/- 4% and decreased the viability of peripheral blood mononuclear cells by 11 +/- 2%. The ability of collagenase supernatants to kill 51Cr-labelled peripheral blood mononuclear cells over four hours was assessed in 16 collagenase supernatants, eight of which produced lysis of 20 +/- 4%. There was no ultrastructural evidence of early degenerative changes in the viable intestinal mononuclear cells fresh from the isolation process or in peripheral blood mononuclear cells incubated in collagenase supernatant. Because prostaglandins are known to inhibit natural killer activity, PGE was measured in 20 collagenase supernatants by radioimmunoassay and found to be high at 27.5 +/- 4.0 ng/ml. Addition of indomethacin to the collagenase medium, however, failed to abolish the inhibitory effect of collagenase supernatant on natural killer activity and did not increase the natural killer activity of isolated intestinal mononuclear cells. The release of cytotoxic and immunomodulatory factors during the isolation of intestinal mononuclear cells indicates the necessity for careful assessment of the potential effects of the isolation process on any function being examined and casts doubt upon the relationship between in vitro findings and in vivo functional capabilities.

Intraepithelial lymphocytes of human gut: isolation, characterisation and study of natural killer activity

A method using a mechanical procedure for isolation of lymphocytes from the epithelium of human intestinal mucosa allows the study of some of their characteristics and functions. Most of the isolated cells are of the T lineage (E+ and T3+) and express the phenotype associated with cytotoxic-suppressor T cells (T8). A large number contain intracytoplasmic granules. Granules are stained with alcian blue (pH 2.2), are metachromatic with Toluidine blue (pH 4) and some are shown to incorporate 35sulphate, suggesting that they contain sulphated mucopolysaccharides. As these cells are similar in many respects to the large granular lymphocytes that mediate natural killer activity in the peripheral blood, their natural cytotoxicity was tested against K 562 target cells. No activity was detected among the human intraepithelial lymphocytes and treatments with known potentiators of natural killer activity, ie, interferon or PHA-depleted conditioned medium containing Il-2, failed to reveal any cytotoxic activity.

Immunology of inflammatory bowel disease

Although the aetiology of ulcerative colitis and Crohn's disease remain unknown, immunological effector mechanisms become activated within the inflamed mucosa and may be responsible for the pathogenesis of chronic disease. There is an increased production of immunoglobulin within the mucosa, some of which has specificity for bacterial antigens, and complement activation occurs during exacerbation of the disease. Lymphocytes isolated from peripheral blood, or from the intestinal mucosa, are cytotoxic to colonic epithelial cells in vitro; a reaction which can be modulated by serum factors and bacterial antigens. Within the mucosa, there are increased populations of T lymphocytes although there is no change in the ratio of helper- to suppressor-cells as defined by phenotype. Studies of immunoregulatory control have shown that there may be alterations in the modulation of the local immune response, especially during active disease, although it is not clear whether these changes are primary or merely secondary to inflammation. It is posulated that many of the humoral and cellular responses to gut-associated antigens occur as a result of increased antigen absorption, increased presentation of antigen to the immune system due to the expression of Class II antigens by the inflamed epithelium and altered immuno-regulatory control.

In situ identification of immune competent cells in gastrointestinal mucosa: an evaluation by immunoelectronmicroscopy

The in situ identification of lymphocyte subpopulations by means of immunopathological techniques using specific monoclonal antibodies provides a tool for the study of the gastrointestinal-associated lymphoid tissue (GALT) in health and disease. In this field, monoclonal antibodies have been applied previously using light microscopy and either immunofluorescence or immunoperoxidase; however, these techniques are not sensitive enough to allow precise evaluation of localization of labelling. We describe an immunoelectronmicroscopic method, which defines labelling specificity, since it allows the identification of cells by immunophenotype labelling and ultrastructural markers simultaneously. This in turn allows a better evaluation of the labelled cells and of the relationship between labelled and unlabelled cells. The main features of the method are the use of fresh tissue samples, fixing in paraformaldehyde CaCl2, and the coupling of the immune reaction to an amplification system (avidin-biotin-peroxidase complex). The technique yields a good preservation of cellular ultrastructure, together with a strong and specific immunolabelling. Our results confirm the high specificity of monoclonal antibodies when applied to immunopathology techniques. We confirm the pattern of distribution of various lymphocyte subsets in the jejunal mucosa described by other authors by light microscopy.

Peripolesis followed by cytotoxicity in chronic idiopathic inflammatory bowel disease

Antigen presenting veiled cells have recently been described in cell suspensions prepared from the gut wall of patients with chronic idiopathic inflammatory bowel disease (CIBD). The normal gut wall is virtually devoid of these cells. In this report we describe a phenomenon known as peripolesis studied by phase contrast cinematography. This is a process in which lymphocytes are seen to wander around larger target cells. These could be identified ultrastructurally as Ia positive veiled cells. In most cases peripolesis was followed by lysis of the target cell. Peripolesis was recorded in cell suspensions of three out of seven patients with ulcerative colitis and in three out of nine patients with Crohn's disease; furthermore peripolesis was observed in one out of two patients with non-classifiable CIBD. In four cell suspensions showing peripolesis, cell lysis could be recorded and was especially striking in ulcerative colitis. Peripolesis involving veiled cells was previously described in delayed hypersensitivity reactions. This study lends support to the concept that delayed allergic reactivity plays a part in chronic inflammatory bowel disease. The antigens involved are, however, completely unknown.

Veiled cells in chronic idiopathic inflammatory bowel disease

The mononuclear cell system in the human gut wall of patients with Crohn's disease (CD), ulcerative colitis (UC) and normal controls was studied, with special reference to the so called antigen presenting veiled cells. These cells have already extensively been studied in the skin and are known as Langerhans' cells in the epidermis and dermis, veiled cells in the skin lymph and interdigitating cells in lymph nodes. Recently they were also found in gut associated lymphoid tissue, i.e. Peyer's patches of the rat. Here we describe the presence of similar cells in chronic idiopathic inflammatory bowel disease (CIBD). They resemble veiled cells in moving pattern, strong Ia positivity, no or only weak acid phosphatase activity, and ultrastructure. However, many of the described cells combine these characteristics with those of phagocytic macrophages. In the gut wall of controls veiled cells were virtually absent and phagocytic macrophages were almost exclusively recognized. These findings suggest that more intensive antigen handling takes place in the gut wall of CIBD patients than in normal gut. Clear cut associations with sex, age, duration or activity of disease were not observed in this limited study, and the exact significance of the presence of such cells needs further clarification.

Intestinal lymphocyte subpopulations in inflammatory bowel disease: an analysis by immunohistological and cell isolation techniques

Lymphocyte subpopulations in the intestinal mucosa of patients with ulcerative colitis or Crohn's disease have been studied using a double marker immunofluorescence technique. Analysis of tissue sections revealed that the majority of intraepithelial lymphocytes (IEL) were T cells (Hle-1+ HuTLA+ UCHT1+). Of these, over 80% were of suppressor-cytotoxic phenotype (OKT8+:83 +/- 10.2%) with a small population of helper type IEL (OKT4+). Only one third of OKT8+ IEL reacted with the T cell antibody, anti-Leu-1. IEL were also Tac-, C3b-receptor- (C3RT05-), and Ig-. Within the lamina propria, OKT4+ T cells predominated (ulcerative colitis 64 +/- 6.0%; Crohn's disease 63 +/- 6.0%). Less than half of the smaller OKT8+ population in the lamina propria was Leu-1+. These finding did not differ from those seen in histologically normal tissues from controls, and are similar to those reported in the small intestine. Mononuclear cells were also isolated from the intestinal lamina propria using an enzymatic technique. The majority of lymphocytes obtained were T cells (OKT3+), with populations of OKT4+ and OKT8+ cells. Comparison of the ratio of OKT4+ to OKT8+ lymphocytes determined by immunohistological analysis with that obtained in mucosal isolates, however, suggested that the isolation procedure may deplete OKT8+ cells. These findings indicate that an imbalance of mucosal immunoregulatory T cells, as defined by monoclonal antibodies, does not occur in inflammatory bowel disease. They also emphasize that functional studies of isolated intestinal mucosal cells should be combined with morphological studies of cell populations in situ.

Imbalance of prostacyclin and thromboxane synthesis in Crohn's disease

Synthesis of prostanoids in Crohn's disease was investigated using rectal biopsy specimens maintained in organ culture. As with ulcerative colitis increased synthesis of prostaglandin (PG)E2 was observed when the mucosa was inflamed, compared with uninflamed mucosa in Crohn's disease, and with control biopsy specimens. In contrast with ulcerative colitis differences from control specimens were observed even in the absence of inflammation. There was a raised synthesis of thromboxane (Tx)B2 (stable breakdown product of TxA2); concentrations of 6-keto PGF1 alpha (stable breakdown product of prostacyclin) were unchanged and hence the ratio of 6-keto PGF1 alpha/TxB2 was reduced. These changes might lead to an altered cytoprotective capacity or reduced suppressor cell activity, such as has previously been reported in intestinal lymphocytes in Crohn's disease.

Ontogeny of non-lymphoid and lymphoid cells in the rat gut with special reference to large mononuclear Ia-positive dendritic cells

The ontogeny of rat Peyer's patches was studied with special reference to Ia-positive dendritic cells. The 16-day-old foetus contained large Ia-positive dendritic cells randomly distributed throughout the gut wall and mesentery. In cell suspensions prepared from the foetal gut, these cells showed the typical movement pattern of veiled cells, and they shared ultrastructural features with these and other antigen-presenting cells. The gut was found to be the first organ in which large numbers of these Ia-positive dendritic cells were found. At 16 days gestation, the Ia-positive dendritic cells were randomly distributed throughout the primitive gut wall, but at later stages accumulated in structures which were clearly recognizable as Peyer's patches from 20 days gestation onwards. T and B lymphocytes could be seen on the day of birth at the earliest, at first randomly distributed throughout the Peyer's patch, but afterwards concentrating in separate T- and B-cell regions. Two weeks after birth Peyer's patches consisted of densely populated B-cell nodules, mainly comprising surface IgM (sIgM) positive cells, and internodular T-cell regions. Ia-positive dendritic cells were situated between the epithelial cells of the dome area, just underneath this epithelium in a loose reticular area and in the internodular T-cell regions. These Ia-positive dendritic cells were acid phosphatase negative or only weakly positive. Some Ia-positive dendritic cells were also present in small intestinal villi at all ages studied. However, these cells started to express an increasing acid phosphatase activity in the 2 weeks following birth. Thus they resemble macrophages, while Peyer's patch dendritic cells show characteristics of antigen-presenting cells.

Immunoregulatory function of human intestinal mucosa lymphoid cells: evidence for enhanced suppressor cell activity in inflammatory bowel disease

Abnormalities in immune regulation at the gut level may be relevant to the pathogenesis of inflammatory bowel disease, but little is known about the immunoregulatory properties of intestinal mononuclear cells. Therefore, we wished to see if lymphoid cells derived from the lamina propria of surgically resected bowel specimens have any modulatory effect upon the immune response of peripheral blood mononuclear cells from patients with ulcerative colitis or Crohn's disease. When autologous peripheral blood and intestinal lamina propria lymphoid cells were mixed at different ratios and cultured in the presence of phytohaemagglutinin, we were able to show that intestinal mononuclear cells had the capacity to modify the mitogenic response of the cultured cells. These intestinal immunoregulatory cells, when obtained from mucosa affected by inflammatory bowel disease, express a significantly enhanced suppressor cell activity as compared with those from non-inflamed control mucosa. Such suppressor cell activity varies with cell concentration and requires cell proliferation, but it is independent of anatomical origin (small vs large bowel), type of inflammatory bowel disease (ulcerative colitis vs Crohn's disease) or immunosuppressive therapy. These findings point to an important functional difference between inflammatory bowel disease and control intestinal mucosa mononuclear cells. The enhanced suppressor activity of lamina propria mononuclear cells may be associated with impairment of cell-mediated immunity at the gut level. This may be related to the pathogenesis of inflammatory bowel disease by leading to defective intestinal immune regulatory events, which may not be detectable at the peripheral level.

Large mononuclear Ia-positive veiled cells in Peyer's patches. I. Isolation and characterization in rat, guinea-pig and pig

The antigen presenting cell system in the skin is extensively studied, and is supposed to consist of Langerhans cells in epidermis and dermis, veiled cells in skin lymph and interdigitating cells in skin lymph nodes. In order to detect whether a similar cell system is present in the gut, we studied Peyer's patch cell suspensions. Mononuclear cells with long actively moving cytoplasmic veils were found in cell suspensions from Peyer's patches of rat, guinea-pig, and pig, and in cell suspensions from small intestinal villi of guinea-pig and pig, but not of rat. These veiled cells are strongly Ia-positive. Because of their Ia positivity, their enzyme cytochemical staining pattern, and their ultrastructure, these cells resemble the antigen presenting cells of the skin, skin lymph and lymph node.

A method for isolation and culture of lymphocytes from endoscopic biopsies

Human small and large intestinal lamina propria lymphocytes have been successfully prepared from endoscopic biopsies by a combined enzymatic and mechanical method which gives higher yields of viable mucosal lymphocytes than previously reported, despite the small size of the biopsy samples. Viability of the cells was demonstrated by dye exclusion and they could be satisfactorily maintained in short-term culture. Phytohaemagglutinin-P (PHA-P) transformation characteristics of intestinal lymphoid cells and those of peripheral blood were studied in 20 patients with Crohn's disease and 10 control subjects. Peripheral blood lymphocytes were separated according to this technique, no decrease in viability being observed when compared to a standard Ficoll-Hypaque gradient technique. Endoscopically abnormal (EA) and endoscopically normal (EN) Crohn's tissue showed significantly different responses to PHA-P (P less than 0.001), EA tissue lymphocytes giving lower blastogenic responses.

Intraepithelial, lamina propria and Peyer's patch lymphocytes of the rat small intestine: isolation and characterization in terms of immunoglobulin markers and receptors for monoclonal antibodies

Methods have been determined for the isolation, purification and subsequent characterization of separate populations of rat intestinal lymphoid cells, namely intraepithelial (IEL), lamina propria (LPL) and Peyer's patch lymphocytes (PPL). Dissociation of the epithelium from the basement membrane with subsequent release of IEL was achieved by citrate buffer incubation followed by vortex agitation. LPL were released from the remaining tissue by scraping, and PPL were similarly obtained. Some preparations of lamina propria were further subjected to collagenase digestion. After filtration and density gradient centrifugation, average yields of 220 x 10(4) IEL, 54 x 10(4) LPL and 220 x 10(4) PPL per gram of gut were obtained. Immunofluorescence characterization demonstrated that cells bearing the MRC OX8 (T-suppressor) marker predominated in IE1 (73%) and were present in lower concentrations in LPL (26%) and PPL (6%). Cells with the W3/25 (T-helper) marker accounted for a small proportion of each of the lymphocyte preparations. IE1 were unusual in containing a population of cells which were negative for the W3/13 marker for T cells, but were MRC OX8 positive. B lymphocytes were present in PPL (55%) and LPL (31%), but were virtually absent in IEL (less than 1%). Few plasma cells were observed. The techniques described will allow functional investigations to be made and lead to a better understanding of mucosal immunity.

Further characterization of lymphocytes from human colonic lamina propria: identification of TG cells

For the first time, TG cells have been identified in human colon using EDTA-collagenase-prepared, macrophage-depleted isolates of lamina proprial lymphocytes (LPL). Specimens of human colon were obtained from patients undergoing surgery for idiopathic inflammatory bowel disease (IBD), colorectal cancer (Dukes' B or C), other colonic inflammations or benign polyps. Of additional interest were quantitative findings which showed lower TG values in LPL from patients with IBD, regardless of disease activity or steroid therapy, and in Dukes' Group C cancers, compared to the other groups. However, these differences of TG values were not reflected in the peripheral blood lymphocytes (PBL) in which, compared to healthy controls, the numbers of circulating TG cells were greater in patients with Dukes' B or C cancers and in those with moderately or severely active IBD receiving steroids. These quantitative differences re-emphasize the need for concurrent observations on PBL and LPL in these diseases, particularly in experiments to determine the functional properties of their TG subsets, including mediation of natural killing, antibody-dependent cellular cytotoxicity and their immunoregulatory properties. The identification of TG cells per se in colonic LPL provides a basis for such studies.

Cytotoxic T cells in small intestine epithelial, lamina propria and lung lymphocytes

We have examined the development of specific cytotoxic T-cell activity in the lungs and the epithelium and lamina propria of the small intestine following tumour cell inoculation by subcutaneous or intraperitoneal routes. After an intraperitoneal injection of tumour cells, large amounts of cytotoxic activity are detectable in the lungs and lamina propria. In comparison, the epithelial lymphocytes of the small intestine display low cytotoxic activity. After a subcutaneous injection, little cytotoxicity is detectable except in the lungs and the development of such cytotoxicity has a much shorter time course compared with that induced by an intraperitoneal inoculation of tumour cells. The data indicate a marked difference in the functional capacity of lymphocytes from the epithelium and lamina propria of the small intestine.

Peripheral, mucosal, and tumour-infiltrating components of cellular immunity in cancer of the large bowel

A reliable technique has been devised for the preparation of colorectal tumour-infiltrating lymphocytes (TIL). The immune capacity of these lymphocytes has been assessed in vitro and compared with that of lymphocytes infiltrating the lamina propria of adjacent normal mucosa (LPL) and with autologous peripheral blood lymphocytes (PBL). Assay of a natural killer (NK) cell function revealed the absence of such activity in TIL and LPL depsite the presence of normal levels in PBL. Antibody-dependent (K cell) cytotoxic activity was also absent in TIL and LPL. Both TIL and LPL showed significant mitogen-induced cytotoxic responses, although higher levels were detected in PBL. Tumour-infiltrating lymphocytes revealed depressed levels of spontaneous DNA synthesis, but mitogen stimulation of TIL was equivalent to that of LPL. T-cell proportions in TIL preparations were equivalent to those in PBL, but LPL comprised significantly fewer T cells.

Studies on isolated gut mucosal lymphocytes in inflammatory bowel disease. Detection of activated T cells and enhanced proliferation to Staphylococcus aureus and lipopolysaccharides

To determine whether a defective proliferation of gut mucosal lymphocytes is a contributory factor to the pathogenesis of inflammatory bowel disease, we assessed their reactivity toward mitogens and bacterial antigens. Spontaneous replication of intestinal lymphoid cells was higher than that of patient-matched peripheral blood lymphocytes. That gut mucosal lymphocytes appear to be activated in loco was confirmed by a striking, time-dependent increase in the number of stable E rosettes generated by culturing unstimulated Crohn's disease intestinal lymphoid cells. The responses of lymphocytes from inflamed and normal mucosa to polyclonal mitogens were not only comparable to each other, but to those of corresponding peripheral lymphocytes, as well. Peripheral blood lymphocytes from patients with Crohn's disease showed less proliferation to Bacteroides and lipopolysaccharide antigens than did those from control individuals, but replicated similarly in response to Staphylococcus aureus and the enterobacterial common antigen: In contrast, when cultured with Staphylococcus aureus or with lipopolysaccharides, but mucosal lymphocytes from Crohn's disease proliferated 3-5 times more than did those from normal mucosa, while lymphoid cells from both sources were equally stimulated by Kunin antigen. Overall, this study found no evidence for a defective proliferative capacity of immune competent cells at the gut mucosal level in inflammatory bowel disease.

Preparation and purification of lymphocytes from the epithelium and lamina propria of murine small intestine

Existing methods for the production of lymphocytes from the small intestine have proved unsatisfactory when applied to the mouse. We report here a new method for the production of highly pure suspensions of lymphoid cells from the epithelial layer and lamina propria of mouse small intestine. The production and purification methods are described in detail. At least ten million lymphocytes are obtainable from each small intestine from either the epithelium or lamina propria and the cell suspensions are shown to be little contaminated by non-lymphoid cells. Preliminary analysis of the two cell types indicates that they belong either to two separate populations or to one population in very different stages of differentiation. The use of purified lymphoid cells from the epithelium and lamina propria of the small intestine may enable examination of the generation of cytotoxicity towards gut epithelial cells; this may be important in the development of inflammatory bowel diseases.

Human colonic intraepithelial and lamina proprial lymphocytes: cytotoxicity in vitro and the potential effects of the isolation method on their functional properties

Colonic mucosal lymphoid cells, selectively enriched for intraepithelial (IEL) or lamina proprial lymphocytes (LPL), were isolated by sequential EDTA-collagenase treatment of resected human colons. Cytotoxic activities of colonic and peripheral blood lymphoid cells (PBL) were tested in three different assays, using chicken erythrocytes (CRBC) and Chang cells as targets. Antibody-dependent cell-mediated cytotoxicity (ADCC) and PHA-induced cytotoxicity (MICC) for both targets were shown by all the isolates of PBL, as was spontaneous cell-mediated cytotoxicity (SCMC) for Chang cells. However, no SCMC or ADCC for Chang cells was found with LPL, and IEL showed minimal or no activity in either assay. PBL, LPL and IEL demonstrated MICC for Chang cells but, contrasting with PBL and LPL, IEL showed no MCC for CRBC. No significant differences were found between the cytotoxic capabilities of colonic lymphoid cells from patients with inflammatory bowel disease and those from patients with other colonic diseases. Importantly, control studies with PBL showed that SCMC for Chang cells and ADCC for CRBC and Chang cells were reduced by collagenase treatment used in the isolation, of LPL. Also, SCMC for Chang cells was reduced by the treatment of PBL with EDTA. In contrast, neither EDTA nor collagenase reduced MICC for CRBC or Chang cells. Both forms of treatment induced variable degrees of cell losses in the PBL. By analogy, it can be implied that the isolation of intestinal mononuclear cells using EDTA and collagenase may influence some of their cytotoxic activities in vitro. This raises an important caveat in the interpretation of such studies.

The early appearance of specific cytotoxic T cells in murine gut mucosa

Using a new technique for isolating lymphoid cells from the lamina propria of murine small intestine, we have examined the appearance of specific cytotoxic T cells in the gut following intraperitoneal immunization with an allogenic tumour. Specific cytotoxic T cells appeared in the lamina propria at a time when there are very few cytotoxic lymphocytes in any of the organized lymphoid tissues. Greater levels of cytotoxicity were found in the gut compared with any other site for at least 3 weeks following a single injection of tumour cells.

Peripheral blood and mesenteric lymph node lymphocytes in Crohn's disease

Analysis of peripheral blood lymphocytes from 44 patients with Crohn's disease showed no difference in the proportions of T- and B-cells from those in 38 healthy controls. Analysis revealed no disturbances in relation to duration or to activity of disease or to drug treatment. Lymphocytes from 18 patients with rheumatoid arthritis also showed normal proportions of T- and B-cells. Lymphocytes taken from gut lymph nodes were studied in five patients with Crohn's disease. On comparison with peripheral blood lymphocytes, significantly decreased proportions of T-cells and significantly increased proportions of B-cells were found in lymph nodes draining areas of diseased bowel. No differences were seen in the proportions of T- and B-cells from lymph nodes taken from apparently healthy bowel of the Crohn's patients and of four control subjects without inflammatory bowel disease, though these were different from those in the peripheral blood in both the Crohn's patients and control subjects.