Increased jejunal intraepithelial lymphocytes bearing gamma/delta T-cell receptor in dermatitis herpetiformis

Improving the Diagnosis of Dermatitis Herpetiformis Using the Intraepithelial Lymphogram

Dermatitis herpetiformis is a cutaneous manifestation of celiac disease. Phenotyping of intraepithelial lymphocytes in the small bowel mucosa can strengthen the diagnosis of celiac disease when it is not clear-cut. We aim to evaluate the usefulness of the intraepithelial lymphogram to confirm dermatitis herpetiformis in equivocal cases. We performed a retrospective multicenter study on patients diagnosed with dermatitis herpetiformis and collected data from the intraepithelial lymphogram assessed by flow cytometry. A total of 36 patients were analyzed in relation to the severity of intestinal damage (18 had non-atrophic mucosa) at baseline (N = 28) and/or after the adoption of a gluten-free diet (median follow-up of three years, N = 16). We observed that patients with atrophy more often had positive celiac serology (p = 0.019), celiac clinical symptoms (p = 0.018), and iron-deficiency anemia (p = 0.018), but the severity of skin damage was similar in both groups (p = 0.79). At baseline, increased TCRγδ+ cells were present in 94% of patients with atrophy and 67% with non-atrophic lesions (p = 0.13). After a gluten-free diet, increased TCRγδ+ cells persisted in 100% and 63% of cases, respectively (p = 0.21). We concluded that increased TCRγδ+ cells may be helpful in confirming the diagnosis of dermatitis herpetiformis in equivocal cases, even in patients who were started on a gluten-free diet.

Lymphocytic duodenitis or microscopic enteritis and gluten-related conditions: what needs to be explored?

Microscopic enteritis (ME) is characterized by abnormal infiltration of intraepithelial lymphocytes in intestinal mucosa. It was described as duodenal lymphocytosis or lymphocytic duodenitis until the dedicated Consensus Conference of 2015. ME represents a common feature of several gluten-mediated and non-gluten related diseases; therefore, it is an umbrella term embracing several conditions. The most frequent causes of ME are gluten-related disorders (celiac disease, non-celiac gluten sensitivity, wheat allergy), Helicobacter pylori infection and drug-related damages. Less frequently, ME may be secondary to inflammatory bowel disease, some autoimmune conditions, immunoglobulin deficiencies, blood malignancies, infections and irritable bowel syndrome. Therefore, the differential diagnosis of ME may be challenging. The diagnosis of ME needs to be driven by predominant symptoms and patient history. However, it is often difficult to achieve an immediate identification of the underlying condition, and a broad variety of diagnostic tests may be required. Ultimately, long-term surveillance is needed for a final diagnosis in many cases, since a hidden or quiescent condition may be disclosed after a period of latency. In any case, strict collaboration between the clinician and the pathologist is pivotal. The treatment of ME should be personalized, depending on the underlying disease. For gluten-related conditions (celiac disease, gluten sensitivity, wheat allergy, dermatitis herpetiformis), a gluten-free diet may be proposed. For other conditions, a targeted etiologic treatment is necessary. In conclusion, ME represents a novel entity that is attracting increasing interest. The growing epidemiologic trend confirms that it will become a common condition in clinical practice.

Primary and Chronic HIV Infection Differently Modulates Mucosal Vδ1 and Vδ2 T-Cells Differentiation Profile and Effector Functions

Gut-associated immune system has been identified as a major battlefield during the early phases of HIV infection. γδ T-cells, deeply affected in number and function after HIV infection, are able to act as a first line of defence against invading pathogens by producing antiviral soluble factors and by killing infected cells. Despite the relevant role in mucosal immunity, few data are available on gut-associated γδ T-cells during HIV infection. Aim of this work was to evaluate how primary (P-HIV) and chronic (C-HIV) HIV infection affects differentiation profile and functionality of circulating and gut-associated Vδ1 and Vδ2 T-cells. In particular, circulating and mucosal cells were isolated from respectively whole blood and residual gut samples from HIV-infected subjects with primary and chronic infection and from healthy donors (HD). Differentiation profile and functionality were analyzed by multiparametric flow cytometry. P-HIV and C-HIV were characterized by an increase in the frequency of effector Vδ1-T cells both in circulating and mucosal compartments. Moreover, during P-HIV mucosal Vδ1 T-cells expressed high levels of CD107a, suggesting a good effector cytotoxic capability of these cells in the early phase of infection that was lost in C-HIV. P-HIV induced an increase in circulating effector Vδ2 T-cells in comparison to C-HIV and HD. Notably, P-HIV as well as HD were characterized by the ability of mucosal Vδ2 T-cells to spontaneously produce IFN-γ that was lost in C-HIV. Altogether, our data showed for the first time a functional capability of mucosal Vδ1 and Vδ2 T-cells during P-HIV that was lost in C-HIV, suggesting exhaustion mechanisms induced by persistent stimulation.

Gene expression profile of peripheral blood monocytes: a step towards the molecular diagnosis of celiac disease?

Aim

Celiac disease (CD) is a multifactorial autoimmune disease induced by ingestion of gluten in genetically predisposed individuals. Despite technological progress, the diagnosis of CD is still based on duodenal biopsy as it was 50 years ago. In this study we analysed the expression of CD-associated genes in small bowel biopsies of patients and controls in order to explore the multivariate pathway of the expression profile of CD patients. Then, using multivariant discriminant analysis, we evaluated whether the expression profiles of these genes in peripheral blood monocytes (PBMs) differed between patients and controls.

Participants

Thirty-seven patients with active and 11 with treated CD, 40 healthy controls and 9 disease controls (Crohn’s disease patients) were enrolled.

Results

Several genes were differentially expressed in CD patients versus controls, but the analysis of each single gene did not provided a comprehensive picture. A multivariate discriminant analysis showed that the expression of 5 genes in intestinal mucosa accounted for 93% of the difference between CD patients and controls. We then applied the same approach to PBMs, on a training set of 20 samples. The discriminant equation obtained was validated on a testing cohort of 10 additional cases and controls, and we obtained a correct classification of all CD cases and of 91% of the control samples. We applied this equation to treated CD patients and to disease controls and obtained a discrimination of 100%.

Conclusions

The combined expression of 4 genes allows one to discriminate between CD patients and controls, and between CD patients on a gluten-free diet and disease controls. Our results contribute to the understanding of the complex interactions among CD-associated genes, and they may represent a starting point for the development of a molecular diagnosis of celiac disease.

Intraepithelial lymphocytes in celiac disease immunopathology

Celiac disease is a T cell-mediated immune disorder induced by dietary gluten that is characterized by the development of an inflammatory anti-gluten CD4 T cell response, anti-gluten antibodies, and autoantibodies against tissue transglutaminase 2 and the activation of intraepithelial lymphocytes (IELs) leading to the destruction of the intestinal epithelium. Intraepithelial lymphocytes represent a heterogeneous population of T cells composed mainly of cytotoxic CD8 T cells residing within the epithelial layer, whose main role is to maintain the integrity of the epithelium by eliminating infected cells and promoting epithelial repair. Dysregulated activation of IELs is a hallmark of CD and is critically involved in epithelial cell destruction and the subsequent development of villous atrophy. In this review, we compare and contrast the phenotype and function of human and mouse small intestinal IELs under physiological conditions. Furthermore, we discuss how conditions of epithelial distress associated with overexpression of IL-15 and non-classical MHC class I molecules induce cytotoxic IELs to become licensed killer cells that upregulate activating NKG2D and CD94/NKG2C natural killer receptors, acquiring lymphokine killer activity. Pathways leading to dysregulated IEL activation could eventually be targeted to prevent villous atrophy and treat patients who respond poorly to gluten-free diet.

Small intestinal CD8+TCRgammadelta+NKG2A+ intraepithelial lymphocytes have attributes of regulatory cells in patients with celiac disease

Intraepithelial lymphocytes (IELs) bearing the gammadelta TCR are more abundant in the small intestinal mucosa of patients with celiac disease (CD) compared with healthy individuals. However, their role in disease pathogenesis is not well understood. Here, we investigated the functional attributes of TCRgammadelta+ IELs isolated from intestinal biopsies of patients with either active celiac disease (ACD) or those on a gluten-free diet (GFD). We found that compared with individuals with ACD, individuals on GFD have a higher frequency of CD8+TCRgammadelta+ IELs that express the inhibitory NK receptor NKG2A and intracellular TGF-beta1. TCR triggering as well as cross-linking of NKG2A increased both TGF-beta1 intracellular expression and secretion in vitro. Coculture of sorted TCRgammadelta+NKG2A+ IELs, IL-15-stimulated TCRalphabeta+ IELs, and HLA-E+ enterocytes resulted in a decreased percentage of cytotoxic CD8+TCRalphabeta+ IELs expressing intracellular IFN-gamma and granzyme-B and surface NKG2D. This inhibition was partially abrogated by blocking either TGF-beta alone or both NKG2A and HLA-E. Thus, our data indicate that suppression was at least partially mediated by TGF-beta secretion as a result of engagement of NKG2A with its ligand, HLA-E, on enterocytes and/or TCRalphabeta+ IELs. These findings demonstrate that human small intestinal CD8+TCRgammadelta+ IELs may have regulatory potential in celiac disease.

Distinct TCR delta repertoires are present in the cutaneous lesions and inflamed duodenum of patients with dermatitis herpetiformis

Intraepithelial gammadelta T cells are increased in the inflamed small bowel and are also found in increased numbers in cutaneous lesions from patients with dermatitis herpetiformis (DH). Thus, these cells might play an important role in the pathogenesis of the disease. We investigated the T-cell receptor (TCR) delta repertoire in involved and non-involved skin and compared it with the TCR delta repertoire of the inflamed duodenum and peripheral blood of the same patients. An identical TCR delta repertoire in the small bowel and in the cutaneous lesions would suggest a migration of antigen-specific gammadelta T cells from the intestine to the skin which cross-react with cutaneous antigens. T-cell receptor DV1-DV3 transcripts were amplified by reverse transcriptase (RT)-PCR and analyzed by complementarity determining region 3 (CDR3) size spectratyping and nucleotide sequencing. Our results indicate that the cutaneous TCR delta repertoires were oligoclonal and identical dominant gammadelta T-cell clones were present in the involved and non-involved skin. Furthermore, the TCR delta repertoire of the skin was distinct from that in the small bowel. The peripheral blood exhibited a restricted TCR delta repertoire, which differed from that in the intestine and skin. Thus, cutaneous gammadelta T cells are not specifically expanded within the involved skin and are unlikely to be derived from the inflamed duodenum.

Histopathology of celiac disease

The diagnosis of celiac disease (CD) is based upon histologic findings in duodenal or jejunal biopsies. In the past few years it has turned out that the development of CD lesion in the small bowel is a dynamic process which may present in various histologic forms. At one end of the spectrum is a mucosa with normal architecture and an increase in intraepithelial lymphocytes (IEL), at the other end is the classical flat mucosa. Histologic features supporting the diagnosis of CD are architectural changes of the villi and/or crypts, an increase in lamina propria cell density and an increase in IEL counts. For diagnostic purposes and for monitoring CD patients an exact histologic classification of the histologic findings has to be given. This has become possible by using a modified Marsh classification. In the present paper the histologic presentation of CD is presented as well as the modified Marsh classification.

gammadelta T-cell lymphomas: a homogeneous entity?

gammadelta T-cells comprise an immunologically distinct lymphoid population, characterized by specific morphological, phenotypical and functional properties. Therefore it seems reasonable to speculate that neoplasms derived from this particular T-cell subset display distinct features. Indeed, the prototype gammadelta T-cell lymphoma, hepatosplenic T-cell lymphoma constitutes a unique clinicopathological entitity which is intimately associated with a gammadelta T-cell phenotype. However, gammadelta T-cell lymphomas have also been described in other extranodal sites where, unlike reactive gammadelta T-cells and hepatosplenic gammadelta T-cell lymphomas, they display an important morphological heterogeneity. Moreover, these nonhepatosplenic gammadelta T-cell lymphomas are essentially not that different from their alphabeta T-cell receptor for antigen (TCR)-expressing counterparts and thus may be incorporated in the established T-cell lymphoma subclasses. However, subtle differences regarding their histopathological appearance as well as their biological behaviour indicate that further studies to determine the exact significance of TCR expression are required. Such inquiries may contribute to the general understanding of T-cell lymphomagenesis in general, which is still obscure.

Antineutrophil cytoplasmic antibody subtypes in children and adolescents after ileal pouch-anal anastomosis for ulcerative colitis

BACKGROUND

Perinuclear antineutrophil cytoplasmic antibodies occur frequently in adult patients with chronic pouchitis after colectomy and ileal pouch-anal anastomosis for ulcerative colitis. The purpose of the study was to determine the prevalence of perinuclear antineutrophil cytoplasmic antibodies and cytoplasmic antineutrophil cytoplasmic antibody in children and adolescents who undergo colectomy and ileal pouch-anal anastomosis for ulcerative colitis and familial adenomatous polyposis.

METHODS

Five groups of children and adolescents (age, <20 years) were studied, with the following histories: acute pouchitis and history of ulcerative colitis; chronic pouchitis and history of ulcerative colitis; pouchitis with Crohn's disease features and a history of ulcerative colitis; no pouchitis and a history of ulcerative colitis; and familial adenomatous polyposis, with or without pouchitis. Antineutrophil cytoplasmic antibody levels and titers were detected in postoperative sera by enzyme-linked immunosorbent assay, and positive results were subtyped by indirect immunofluorescence.

RESULTS

The frequency of perinuclear antineutrophil cytoplasmic antibodies and cytoplasmic antineutrophil cytoplasmic antibody in patients with a history of ulcerative colitis were 67% and 15%, compared with a 0% presence in patients with familial adenomatous polyposis (p < 0.001). There was no significant correlation between the frequency of perinuclear antineutrophil cytoplasmic antibodies and ulcerative colitis patient subgroups (patients with and without pouchitis, 66% and 75%). Similarly, there was no significant correlation between the frequency of cytoplasmic antineutrophil cytoplasmic antibodies among ulcerative colitis patient subgroups (patients with and without pouchitis, 19% and 8%). The frequency of cytoplasmic antineutrophil cytoplasmic antibody in patients with Crohn's disease features (50%), was increased, but this difference was not significant.

CONCLUSIONS

There is a high frequency of perinuclear antineutrophil cytoplasmic antibodies in children and adolescents who undergo ileal pouch-anal anastomosis for ulcerative colitis, whether or not they have pouchitis. The frequency of cytoplasmic antineutrophil cytoplasmic antibody is lower in this patient population. Additional studies will be required to determine whether the presence of cytoplasmic antineutrophil cytoplasmic antibody is associated with the postoperative development of features of Crohn's disease.

Abdominal T-cell non-Hodgkin's lymphoma of the gamma/delta type in a patient with selective immunoglobulin A deficiency

A 28-year-old man presented with selective immunoglobulin A deficiency and severe diarrhea responding to a gliadin-free diet. Biopsy samples of the small intestine showed dense T-cell infiltrations in the lamina propria and a slight increase of intraepithelial T-lymphocytes. No clonal rearrangement of the T-cell receptor c-beta chain genes was detectable by Southern blotting. Four years later, at the age of 32, the patient was hospitalized again with liver failure, abdominal lymphadenopathy, pancytopenia, and recurrent bacterial infections. Retrospective polymerase chain reaction analysis of formalin-fixed tissues of the intestinal biopsy samples obtained 4 years earlier showed monoclonal T-cell receptor gamma-chain gene rearrangement. Lymphoid cells of the peripheral blood showed an immunophenotype of CD3-positive gamma/delta T cells with a negativity for CD4 and CD8. A clonally rearranged T-cell receptor delta chain gene and a germline configuration of the c-beta chain genes was found by Southern blotting. Cytogenetics showed an abnormal karyotype with unbalanced translocations t(1;5) and t(9;13). The patient died of extensive lung infiltrations by gamma/delta T cells; autopsy showed a peripheral T-cell lymphoma of the gamma/delta type in the enlarged abdominal lymph nodes. This is the first report of an abdominal T-cell lymphoma of the gamma/delta type in a patient with selective immunoglobulin A deficiency.

[Dermatitis herpetiformis occuring in patients with celiac disease in childhood]

BACKGROUND

Dermatitis herpetiformis (DH) is a chronic papulovesicular immune-mediated disorder associated with gluten-sensitive enteropathy. We report eight cases in which DH appeared many years after celiac disease (CD) in child.

PATIENTS AND METHODS

The diagnosis of CD was based on histological features of total or subtotal villous atrophy, full remission after withdrawal of gluten from the diet, and eventually circulating antibodies (IgA gliadin, antireticulin and antiendomysium) at the time of diagnosis and their disappearance under gluten-free diet. The diagnosis of DH was made from clinical findings, histological examination of the involved skin and direct immunofluorescence microscopy of normal or perilesional skin. HLA class II typing was performed in five patients. DRB1, DQA1, DQB1 and DBP1 alleles were studied.

RESULTS

DH appeared between 3 and 22 years after the initial diagnosis of CD. Five patients did not show at that time any digestive symptoms. In three cases, a break in the gluten-free diet or a recent revival of the normal diet preceded the rash. In only one case, DH appeared while the patient was under gluten-free diet. In three patients, the rash appeared many years after the gluten-free diet had been stopped. Phenotype DR3 and/or DR7 of the celiac disease could be found in four of the five patients studied; three of them were found to bear DQW2. The DR2 allele was not found in any of the five tested patients.

DISCUSSION

These eight cases illustrate the absence of precise nosological barrier between gluten-sensitive enteropathy of the DH and that observed in CD. The presence of the DR7 allele, and especially the absence of the DR2 allele, could explain the particularly severe and symptomatic course of the enteropathy in these patients. The delay in the appearance of DH, after a very variable period of normal diet, could correspond to the necessary time for progressive accumulation of IgA (or immune complex IgA-gluten) in the skin after a digestive sensitization to gluten. The preventive role of gluten-free diet is thus probable.

CONCLUSION

CD and DH likely correspond to two different stages of the same disease, thus requiring a prolonged follow-up of both digestive and skin tissues. Long-term eviction of gluten to prevent eventual DH must be balanced with the demand and the cost of such a diet.

Intraepithelial gamma/delta T cells in duodenal mucosa are related to the immune state and survival time in AIDS

The proportion of T-cell receptor gamma/delta+ cells and the CD4/CD8 ratio relative to all CD3+ intraepithelial lymphocytes (IEL) were determined by immunofluorescence in duodenal mucosa of late-stage (mostly CDC IVC1/D) subjects (n = 21) infected with human immunodeficiency virus type 1 (HIV-1). The gamma/delta fraction (median, 14.2%; range, 1.7 to 59.8%) was increased (P < 0.03) compared with that in HIV- controls (n = 11; median 2.8%; range, 0.3 to 38%). Also, the number of gamma/delta+ IEL per mucosal unit was increased (P < 0.05) in the HIV+ subjects (median, 11.1/U) compared with the controls (3.2/U). Approximately 100% of the gamma/delta+ IEL were CD8-, and most expressed the Vdelta1vJdelta1-encoded epitope (median, 90.9%). The total number of CD3+ IEL tended to be lower than in the controls (67.4 versus 72.9/U). Both the epithelium and the lamina propria contained mainly CD8+ T cells, the median ratios of CD4+ T cells being 1 and 7.6%, respectively. This result accorded with the reduced CD4 cell number in blood (median, 18 X 10(6)/liter). The HIV+ subjects had increased serum levels of neopterin and beta2-microglobulin (both P < 0.0001), probably reflecting immunostimulation. Serum neopterin and beta2-microglobulin were inversely related to duodenal gamma/delta IEL, particularly in the premortal group (r = -0.97 and r = -0.58, respectively). The increased gamma/delta IEL might reflect enhanced intestinal protection in late-phase HIV infection. Short survival expectancy (<7 months) was associated not only with high levels of neopterin and beta2-microglobulin but also with a reduced number of duodenal gamma/delta+ cells (P < 0.03).

Lack of proliferative response by gluten-specific T cells in the blood and gut of patients with dermatitis herpetiformis

The majority of patients with Dermatitis Herpetiformis (DH) have a gluten-sensitive enteropathy which may be triggered by a T cell-mediated immune response to gluten. Using a proliferative assay, the responses to gluten fraction III, recall antigens and mitogens of peripheral blood mononuclear cells (PBMC) and gut T cell lines (TCL) isolated from patients with Dermatitis Herpetiformis (DH) and normal controls were studied. In most cases, neither PBMC nor gut T cell lines (which were predominantly CD3+, CD4+, TCR alpha beta +) from either controls or patients proliferated in response to gluten fraction III alone. However, the addition of 10 U/ml IL-2 to PBMC cultures containing gluten fraction III resulted in a marked increase in proliferation in 9/19 DH patients and 7/11 controls compared to IL-2 alone. Furthermore, gluten-induced upregulation of IL-2 receptor (CD25) expression was demonstrated on PBMC from 4/4 patients with DH and 2/3 controls after 7 days' culture with antigen. A similar effect by exogenous IL-2, or the same concentration of IL-4, was observed in 8/11 (P = 0.02) and 5/6 respectively DH, and 3/4 normal gut T cell lines. No difference was observed in the response of DH and control PBMC to Tetanus toxin, Candida albicans and PPD; both normal and DH gut T cell lines were unresponsive to these antigens. However, the addition of IL-2 increased the response to Candida albicans by DH gut T cell lines. Moreover, the response of DH gut T cell lines to PHA (P < 0.001), Concanavalin A and anti-CD3 were markedly reduced compared to PBMC from the same patients. These findings suggest that gluten-specific T cells present in the blood and gut of normal and DH individuals are activated by but do not proliferate in response to specific antigen.

T lymphocytes bearing the gamma/delta T-cell receptor in cutaneous lesions of dermatitis herpetiformis

T lymphocytes bearing the gamma/delta T-cell receptor are a rare component of normal human GI epithelium and skin. Recently, however, an unusually high percentage of T lymphocytes with gamma/delta receptors has been described in gastrointestinal biopsies from patients with dermatitis herpetiformis, implicating the gamma/delta T cell subset in the pathogenesis of this disease. We investigated a possible role for this subset of lymphocytes in the pathogenesis of the cutaneous lesions of dermatitis herpetiformis. Using a standard immunoperoxidase technique, we labelled perilesional skin biopsies from patients with dermatitis herpetiformis and other inflammatory dermatoses with monoclonal antibodies to CD3, CD4, CD8, alpha/beta T cell receptor, gamma/delta T cell receptor, and IL-2 receptor. We found no differences in the percentage of gamma/delta positive T lymphocytes in skin lesions of dermatitis herpetiformis as compared to other selected inflammatory conditions. These findings suggest that the pathogenesis of the cutaneous lesions of dermatitis herpetiformis is not mediated through gamma/delta T cells, and that the cutaneous lesions may develop through mechanisms different from those operative in the gastrointestinal tract.

Characterization of the inflammatory cell populations in normal colon and colonic carcinomas

Little is known about the nature of the mucosa-associated immune system within the normal colon, or about the immune response to colon carcinoma. In this study inflammatory cells (ICs) in 14 normal colons and 14 carcinomas were characterized. Overall inflammation, lymphocytes, plasma cells, neutrophils, and eosinophils were graded in routine H & E sections. Frozen sections were stained by an immunoperoxidase technique using antibodies to the T cell associated antigens CD2, CD7, CD4, CD8, and T cell receptors alpha beta and gamma delta. B cells were identified with CD20, macrophages with CD68, and Class II antigen with anti-HLA DR. Each cell type was semiquantitatively graded in 10 high power fields (HPFs) in the lumenal half (LH) or basal half (BH) of the normal mucosae, and in epithelium or stroma of the carcinomas. In normal colons, ICs were more frequent in LH than in BH. Plasma cells, lymphocytes and monocytes predominated. Subtyping of lymphocytes showed that CD4+ TCR alpha beta + T lymphocytes were most numerous in the lamina propria. Lymphocytes within the epithelium were CD8+ T cells. Around carcinomas the overall grade of ICs was 1+ in the majority of cases. Plasma cells, CD4+ and CD8+ cells with the TCR alpha beta receptor, and macrophages were most frequent. Lymphoid aggregates of both T and B cells were frequent.

CONCLUSIONS

1. Normal colon contains a diffuse luminally oriented population of TCR alpha beta+ CD4+ T cells, plasma cells, macrophages and class II antigen-expressing cells in the lamina propria.(ABSTRACT TRUNCATED AT 250 WORDS)

Duodenal intraepithelial gamma/delta T cells and soluble CD8, neopterin, and beta 2-microglobulin in serum of IgA-deficient subjects with or without IgG subclass deficiency

Expression of the gamma/delta T cell receptor (TCR) on CD3+ intraepithelial lymphocytes (IELs) was studied by two-colour immunofluorescence in duodenal tissue sections from healthy (n = 6) or infection-prone (n = 7) subjects with selective IgA deficiency (IgAD), and subjects (n = 4) with combined IgAD and IgG subclass deficiency. TCR gamma/delta+ IEL proportions in selective IgAD subjects (median 6.3%, range 1.0-41%) and in those with combined deficiency (median 4.5%, range 1.2-33%) were well within the range (0.3-38%) for histologically normal controls (n = 11), but the healthy IgAD subgroup tended to show raised TCR gamma/delta+ IEL proportions (median 13.6%) compared with the other two subgroups. Also the number of TCR gamma/delta+ IELs per intestinal length unit was relatively high (median 13.9/mm) in the healthy IgAD subjects, and significantly raised (P < 0.03) compared with controls (median 3.2/mm). Paired staining revealed that most TCR gamma/delta+ IELs in both selective IgAD (98%) and combined deficiency (99%) were CD8-, and a large fraction (median 84% and 63%, respectively) expressed the V delta 1/J delta 1-encoded epitope. The total number of CD3+ IELs (mostly CD8+) was similar to controls. IgAD subjects, and especially the healthy subgroup, had significantly increased serum concentrations of soluble CD8 (P < 0.0002), neopterin (P < 0.005), and beta 2-microglobulin (P < 0.007), which was similar to our previous observations in common variable immunodeficiency, and probably reflected stimulation of cell-mediated immunity. In addition, the increased TCR gamma/delta+ IELs might reflect a component of compensatory surface protection in the healthy IgAD subgroup.