Lymphocyte subsets in the blood: a diagnostic window on the lymphoid system?

Changes in lymphocyte subsets with age in perinatal cats: late gestation through eight weeks

The age-related changes in numbers and proportions of peripheral blood lymphocyte subsets (pan-T, CD4, CD8, Ig, and null) were evaluated by two-color flow cytometry in 16 feline fetuses (56-58 days gestational age) and 21 kittens from birth through 8 weeks of age. Populations of pan-T+, CD4+, and CD8+ cells increased in total numbers as a function of increases in total lymphocyte numbers while proportions of these subsets remained relatively static. In contrast, both the total number and proportion of Ig+ cells increased from birth to 4 weeks of age, after which there were essentially no changes. Null (pan-T-, Ig-) cells were highest during late gestation and declined steadily thereafter to become a minimal component of the peripheral lymphocyte subsets. Compared with normal adult values, CD4/CD8 ratios were high throughout the 8 week study period. These results illustrate that the neonatal cat blood lymphocyte profile undergoes maturational changes and emphasize the importance of evaluating age-matched controls in studies of conditions that may alter feline lymphocyte subsets.

An analysis of the normal ranges of lymphocyte subpopulations in children aged 5-13 years

Peripheral blood lymphocytes subsets were examined in 233 healthy school children aged 4.9-13.7 years at the time of examination. Lymphocyte subsets were characterized according to the following cluster of differentiation (CD) numbers: CD2, CD4, CD8 and CD19 and quantified according to both their absolute number and as a percentage of total lymphocytes. For the purpose of analysis, the LMS (lambda, mu, sigma) method was utilized, with a 3%-97% confidence interval. Smoothing of the generated curves, was by multiple regression analysis, using the least squares method. The results of these analyses indicate distinct trends as a child ages, both in absolute numbers and in the percentage of each cell type.

CONCLUSION

We characterized lymphocyte subsets in children aged 4.8-13.7 years. These data should prove of considerable value to pediatricians dealing with patients with known or suspected immunological problems, and ought to be used in place of the commonly used, but inappropriate, adult lymphocyte subset ranges.

Dysregulation between TH1 and TH2 T cell subpopulations in the elderly

We investigated the influence of zinc and its binding proteins on the immune system in 21 elderly and 20 young subjects. We detected a deficiency of zinc in the serum of the elderly. Albumin levels were within physiological range, but alpha 2-macroglobulin was significantly increased in the serum of elderly subjects. Using a whole blood assay, we found decreased production of interferon-gamma (IFN-gamma) and soluble interleukin-2 receptors (SIL-2R) in the elderly, whereas interleukin-10 (IL-10) production was greater than in the young controls. To exclude cellular defects, we measured lymphocyte subpopulations. In elderly subjects, we detected lower quantities of CD8+, CD8+/CD45RA+ and CD4+/CD45RO+ cells, but not CD4+ cells, than in young subjects. Other lymphocyte subpopulations were comparable for both groups. These findings suggest a dysregulation between TH1 cells and TH2 cells in the elderly, which may be a result of long-term zinc deficiency. Zinc reconstitution showed no beneficial effects as measured by T cell activity.

Lymphocyte subset abnormalities in German shepherd dog pyoderma (GSP)

Peripheral blood lymphocyte subpopulations were studied in 12 German shepherd dogs suffering from deep pyoderma (GSP). Twelve other healthy but matched dogs were used as controls. GSP was found to be associated with an imbalance in the CD4 and CD8 subsets (respectively 37.3 +/- 8.7% and 28.6 +/- 6.6%, as compared to 47.5 +/- 8.8% and 19.3 +/- 4.0% in the controls). The activation markers were not affected by GSP. Moreover, analysis of the B-cell populations showed a striking decrease in the level of CD21 cells (5.5 +/- 3.3% of CD21+ lymphocytes, compared to 12.2 +/- 6.0 in the controls). This study suggests that the immunological imbalance observed in GSP may be associated with defective helper cells, and provides further evidence that dogs suffering from GSP are not immunologically normal reactors.

The neuropeptide substance P does not influence the migration of B, T, CD8+ and CD4+ ('naive' and 'memory') lymphocytes from blood to lymph in the normal rat

Thoracic duct lymphocytes (TDL) continuously patrol through the body, facilitating immune responses at most sites. The neuropeptide Substance P might regulate immune responses by influencing the migration of TDL. Therefore, it was investigated whether Substance P affects the migration of thoracic duct B, T, CD8+ and CD4+ ('naive' and 'memory') lymphocytes from blood to lymph in vivo. Labelled TDL were either incubated with Substance P and then injected into normal rats, or incubated without Substance P and then injected into rats continuously receiving Substance P intravenously. The numbers of labeled B, T, CD8+ and CD4+ ('naive' and 'memory') lymphocytes were determined in blood and thoracic duct lymph for 1 and 5 days, respectively. Neither the in vitro incubation with Substance P nor its in vivo application influenced the disappearance of any lymphocyte subset from the blood or its reappearance in the lymph. In addition, continuous intravenous application of the Substance P antagonist CP 96.345 did not alter the volume or the lymphocyte number of the efferent lymph. The present study indicates that the nervous system does not influence immune responses via Substance P by altering the migration pattern of B, T, CD8+ and CD4+ ('naive' and 'memory') lymphocytes.

Measurement of apoptotic cells in peripheral blood

The measurement of apoptosis in peripheral blood might represent a useful tool in acquired immunodeficiency syndrome (AIDS) and cancer research. Among the many assays that are currently used to identify apoptotic leukocytes, flow cytometric methods are the most valuable in terms of rapidity, simplicity, and level of analytical detail. Some flow cytometric assays may also offer the additional advantage of detecting the earliest phases of apoptosis, which is paramount importance for measuring apoptotic cells in vivo before they are destroyed by phagocytes.

The macrophage-T-lymphocyte theory of schizophrenia: additional evidence

Chronically activated macrophages and T-lymphocytes, along with excessive interleukin-2 and other cytokine secretions, were previously proposed as the fundamental mediators of schizophrenia. This paper provides further support for the immune model of schizophrenia, including evidence on neurotransmitter abnormalities, the low amplitude of the auditory P300 event-related potential, the neurodevelopmental model of schizophrenia and the possible involvement of the locus ceruleus in schizophrenia.

Reduced CD8+ peripheral blood T lymphocytes in rapidly progressive periodontitis

The peripheral blood T-cell phenotype of patients with rapidly progressive periodontitis (RPP) was determined in order to investigate whether there were T-cell imbalances or not. Twenty patients aged 21-39 yr were selected for this study. Bone resorption and probing pocket depth were measured. All the patients had 10 or more teeth showing bone loss of 50% or more. As controls, 12 periodontally healthy, age-matched individuals were selected. Blood samples were obtained by venipuncture, and lymphocytes were isolated. Two-colour flow cytometric analysis was done with monoclonal antibodies against human CD4, CD8, and CD45RA antigens. The RPP patients were found to have significantly lower percentage of CD8+ T cells (Mann-Whitney's U-test, p < 0.01) and an increased CD4/CD8 ratio (Mann-Whitney's U-test, p < 0.01) compared with healthy individuals. On the other hand, there were no significant differences in the percentages of CD4+ T cells and CD4+ CD45RA+ T cells between RPP patients and healthy individuals. No correlations between the clinical findings and T-cell subsets were found. These findings suggest that imbalances of peripheral blood T lymphocytes, especially a tendency to decreased CD8 + T cells, exist in RPP patients, and that cellular immune responses mediated by CD8 + T cells may play a part in the pathogenesis of RPP.

Decreased human immunodeficiency virus type 1 plasma viremia during antiretroviral therapy reflects downregulation of viral replication in lymphoid tissue

Although several immunologic and virologic markers measured in peripheral blood are useful for predicting accelerated progression of human immunodeficiency virus (HIV) disease, their validity for evaluating the response to antiretroviral therapy and their ability to accurately reflect changes in lymphoid organs remain unclear. In the present study, changes in certain virologic markers have been analyzed in peripheral blood and lymphoid tissue during antiretroviral therapy. Sixteen HIV-infected individuals who were receiving antiretroviral therapy with zidovudine for > or = 6 months were randomly assigned either to continue on zidovudine alone or to add didanosine for 8 weeks. Lymph node biopsies were performed at baseline and after 8 weeks. Viral burden (i.e., HIV DNA copies per 10(6) mononuclear cells) and virus replication in mononuclear cells isolated from peripheral blood and lymph node and plasma viremia were determined by semiquantitative polymerase chain reaction assays. Virologic and immunologic markers remained unchanged in peripheral blood and lymph node of patients who continued on zidovudine alone. In contrast, a decrease in virus replication in lymph nodes was observed in four of six patients who added didanosine to their regimen, and this was associated with a decrease in plasma viremia. These results indicate that decreases in plasma viremia detected during antiretroviral therapy reflect downregulation of virus replication in lymphoid tissue.

Peripheral blood lymphocyte subset distribution and function in patients with Alzheimer's disease and other dementias

BACKGROUND

Until recently, new data on immune aspects of Alzheimer's disease (AD) have suggested that some facets of AD pathogenesis may be immune related. However, the effects of dementia itself on immune function have not been considered.

AIM

To compare the distribution of peripheral blood lymphocyte subsets and their function in patients with AD and other dementias.

METHODS

Peripheral blood lymphocyte numbers, T cell subset distribution, proliferative responses to mitogens and suppressor cell assay were studied in a well characterised group of patients with AD, and compared to patients with other forms of dementia. Age and sex matched elderly controls were screened to exclude dementia, and young controls were medical, paramedical and laboratory staff. Analysis of variance (ANOVA) and student's test were used for statistical analysis.

RESULTS

The CD8+ lymphocyte population was reduced in AD and in other forms of dementia, when compared with non-demented elderly and young controls. Concanavalin A induced lymphocyte transformation was reduced in all dementia groups and in elderly compared with young controls. The changes in T cell numbers and function were not specific for Alzheimer's disease, but were found also in other forms of dementia.

Flow cytometric analysis of peripheral blood lymphocyte subset light scatter characteristics as a means of monitoring the development of rat small bowel allograft rejection

This investigation used flow cytometry to monitor peripheral blood lymphocyte morphology after rat small bowel transplantation. Preliminary studies demonstrated that in vitro activated peripheral blood lymphocytes exhibited increased cell size and granularity as measured by flow cytometric analysis of forward (FSc) and side (SSc) light scatter characteristics. The formation of distinct 'activated' light scatter regions by such lymphoblastoid transformation occurred concomitantly with up-regulated p55IL-2R expression. Heterotopic small bowel transplantation was performed between PVG donor and DA recipient rats without immunosuppression. Animals receiving isografts served as controls. Peripheral blood lymphocyte subsets were identified using appropriate MoAbs, and the light scatter characteristics of each cell subset were determined by backgating strategies. Increased proportions of activated alpha/beta T cell receptor (TCR)-positive cells could be detected in allografted animals as early as day 2 post-transplantation. B cells showed peak activation by day 4, at which time the proportion of activated cells was over two-fold greater than that seen in untransplanted animals--few activated B cells were detected in isografted animals. Resting natural killer (NK) cell light scatter regions only partially overlap with those of resting T and B lymphocytes, but in allografted animals almost the entire NK population fell outside the resting lymphocyte gate by day 2 post-transplantation, an activation state which was maintained until day 4. These findings associate peripheral blood cell subset lymphoblastoid transformation with developing small bowel allograft rejection. Importantly, changes were detected early and prior to the onset of overt rejection. These data suggest that analysis of peripheral blood lymphocyte light scatter properties may provide an insight into in vivo immune status after small bowel transplantation.

Interaction of B and T lymphocyte subsets with high endothelial venules in the rat: binding in vitro does not reflect homing in vivo

Lymphocytes continuously migrate through the body, and their efficient extravasation from the blood via high endothelial venules (HEV) is essential for initiating an appropriate immune response. Most investigations have focused on the lymphocyte/HEV interaction in vitro. However, to what extent such systems reflect the situation in vivo is not known. It is also unclear whether lymphocyte subsets immigrate into the HEV in proportion to their presence in the blood, and whether import capacity is limited by the HEV. When rat mesenteric lymph node lymphocytes were incubated in vitro on cryostat sections, the well-known preferential binding of B lymphocytes to HEV of Peyer's patches (PP) and T cells to HEV of axillary lymph nodes (axLN) was observed (axLN vs. PP: B lymphocytes 21.2 +/- 5.0% vs. 40.6 +/- 11.0%, T lymphocytes 84.6 +/- 6.3% vs. 56.5 +/- 12.9%). However, when labeled mesenteric lymph node lymphocytes were injected and their location within the HEV was analyzed 15 min later, no preferential interaction was seen. After injection of labeled thoracic duct lymphocytes, the percentage of labeled cells among B and T lymphocytes in the blood was significantly different (4.4 +/- 0.9% vs. 8.9 +/- 3.6%), whereas that in HEV of axLN (19.0 +/- 6.4% vs. 16.6 +/- 6.0%) and PP (30.6 +/- 6.1% vs. 33.9 +/- 4.4%) was comparable. Although the number of injected lymphocytes was similar in magnitude to the total blood lymphocyte pool, after injection there was no increase in lymphocyte numbers in the HEV. Thus, the adhesion assay in vitro does not completely reflect immigration into HEV in vivo. In addition, our data suggest that both the availability of lymphocyte subsets in small venules and the immigration rate into HEV are actively regulated in vivo.

Studies on the phenotypic and functional characterization of peripheral blood lymphocytes from patients with early-onset periodontitis

Juvenile and rapidly progressive periodontitis are grouped under the heading of patients with early-onset periodontitis (EOP). Many studies have investigated host risk factors in the etiology of EOP patients but these remain inconclusive. This study was undertaken to assess the possibility that an abnormality in the systemic lymphocyte subpopulation or function is involved in the etiology of EOP patients. Fourteen (14) patients with juvenile periodontitis (JP), 18 with rapidly progressive periodontitis (RPP), 22 with adult periodontitis (AP), and 33 with a healthy periodontium (HP) participated in this study. Lymphocyte subsets were determined by using panels of monoclonal antibodies (mAbs) and fluorescent flow cytometry. T cell blastogenesis was evaluated by [3H]-thymidine uptake. Pokeweed mitogen induced immunoglobulin G (IgG) and IgM synthesis were detected by sandwich enzyme-linked immunosorbent assay. There were wide distributions of values in all examinations among subjects. No significant difference could be found between the periodontitis patients and HP groups with the exception of a high CD4/CD8 ratio in all patient groups (P < 0.0001) and the depressed percentages of CD3 positive cells noted in the AP patient group (P < 0.0001). These results suggest that the majority of EOP patients do not show significantly different lymphocyte profiles from AP patients and HP subjects, and that lymphocyte cell dysfunctions are not always seen, even in EOP patients.

Clinical and laboratory studies on a patient with early onset periodontitis and her family members. A case report

Extensive clinical, microbiological, hematological, and immunological studies were performed on a patient with early onset periodontitis (EOP) and two other members of the family. The proband, a 27-year-old female, had early onset periodontitis and a high level of serum rheumatoid factors (RF) with no diagnosable medical disease. Her mother had lost all her teeth at the age of 50 because of advanced periodontitis, while her elder sister was unaffected by periodontitis. Neither the proband's periodontally-affected mother nor her unaffected sister exhibited a detectable level of RF. In this study, we examined: 1) serum immunoglobulin G (IgG) antibody titers against putative periodontal pathogenic bacteria; 2) peripheral neutrophil functions; 3) phenotypic analyses of peripheral lymphocyte subpopulations; and 4) peripheral lymphocyte functions (T cell proliferative activity, ability of cytokine [interleukin (IL)-2, tumor necrosis factor-alpha, interferon-gamma, IL-6 and IL-8] and IgG and IgM productivity). High antibody titers to Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Campylobacter rectus were detected in the sera of the proband, as were high serum antibody titers to P. gingivalis in the mother and to C. rectus in the unaffected sister compared to the non-periodontitis affected subjects. The proband also showed enhanced neutrophil chemotaxis; a high percentage of pan-B cells; and high productivity of IL-6, IgG, and IgM compared to individuals who were not periodontally affected. The mother showed slightly low helper/induced T cells (Th/i) suppressor/cytotoxic T cells (Ts/c) ratios due to the elevated count of Ts/c, and high IFN-gamma productivity compared to control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective recruitment of lymphocyte subsets to the inflamed appendix

Total lymphocyte counts and the distribution of lymphocyte subsets were determined in peripheral venous blood and appendiceal mononuclear cells from 60 patients who underwent appendicectomy for the clinical diagnosis of appendicitis. A significant peripheral lymphopenia was observed in the 46 patients with histologically confirmed acute appendicitis which was accompanied by an increase in the appendiceal lymphocyte concentration. There was an even greater depletion of CD45RO+ (memory) T lymphocytes in peripheral blood and an increase in the inflamed appendix. Reciprocal changes were observed in the CD45RA+ (naive) T lymphocyte subset. These changes were reflected in the local arterial and venous CD45RA and CD45RO T lymphocyte subsets. Proliferation studies showed an expanded functional repertoire of T lymphocytes in the inflamed appendix. Selective recruitment of memory T lymphocytes from the peripheral blood to the inflamed appendix was demonstrated.

Individual differences in cell-mediated and humoral immunity in pigs

Previous experiments displayed consistent individual behavioural differences in pigs. Some showed a more active behavioural response (aggressive and resistant; so-called A/R pigs), other a more passive behavioural response (non-aggressive and non-resistant; so-called NA/NR pigs). Moreover, these behavioural coping strategies were associated with different behavioural, physiological and endocrine responses under stress conditions. In the present study we selected 32 A/R and 32 NA/NR individuals and tested their immune reactivity in reaction to stress using several cell-mediated (CMI) and humoral immunological tests. Active A/R pigs had a higher in vivo and in vitro CMI to nonspecific and specific antigens, while after stress CMI reduced more in A/R than in NA/NR pigs. In contrast, humoral immunity was highest in NA/NR pigs. Furthermore, some serologically typed swine lymphocyte antigen (SLA) class I haplotypes were not equally distributed between A/R and NA/NR pigs. In general, these findings show that measurement of immune reactivity is an important tool to define how animals cope with environmental demands.

Silicone breast implants: the role of immune system on capsular contracture formation

We evaluated the role of the immune system in the pathogenesis of the periprosthetic capsular contracture, the most frequently occurring complication following the implant of silicone prostheses. Peripheral blood samples from 22 patients with silicone-gel-filled implants were examined. In all cases a capsule was felt by palpation, and it was classified according to the Baker scale. Ten patients (group 1) had a Baker 2 contracture, and 12 (group 2) had severe contracture rated 3 and 4. The cells positive to antigens CD3, CD4, CD8, HLA-DR, CD19, CD25, CD57, CD16, and CD14, and the cytotoxic activity of the lymphocytes on target cells K562 were assessed by cytofluorimetric analysis. At time 0 there were no statistically significant differences between patients and normal subjects, nor between the two groups. At 48 h, the group 2 patients had a number/mm3 of cells CD57 + significantly higher than both group 1 and control group (P < .05). In group 1 patients, the cytotoxic activity was similar to that of normal subjects, whereas in group 2 it was significantly increased, in respect to both the controls (P < .05) and group 1 (P < .001). In all groups, the contact of the lymphocytes with the silicone extract did not modify either the antigen expression or the lymphocyte functional activity. On the basis of these results we hypothesize the involvement of the immune system in the formation of the capsular contracture around the prosthesis.

Investigations on autologous T-cells for adoptive immunotherapy of AIDS

We report on the preclinical results of an immunotherapeutic approach of AIDS mediated by ex vivo propagated CD4+ and CD8+ T-cells. A mean yield of 6.23 x 10(9) lymphocytes, containing 1.82 x 10(9) CD4+, 3.23 x 10(9) CD8+ T-lymphocytes and 8.39 x 10(6) CD34+ peripheral blood progenitor cells (PBPC) were be obtained by continuous flow cytapheresis (CFC) in 15 asymptomatic HIV infected patients (CD4-count > 350/mm3). The CD4/CD8 ratio (mean: 0.53, SD: +/- 0.15) in the cell concentrates reflected the distribution of the circulating lymphocyte subsets in vivo. Absolute lymphocyte counts decreased at a mean of 404/microliter (25%) immediately after CFC but were replaced from the extravascular pool within one hour. Neither the CD4/CD8 ratio nor p24-antigen and neopterin levels did change significantly after cell separation. No alteration of the number of proviral DNA copies (1/10(3)-1/10(6)) could be detected in peripheral T-helper cells by semiquantitative PCR after lymphapheresis. Cells were cryopreserved in liquid nitrogen without substantial loss of viability or function. Ex vivo propagation of T-cells in a strictly autologous manner in the presence of PHA + IL-2 for 14d resulted in a 50-fold expansion rate (140-fold in healthy controls, p < 0.001). Viral replication could be controlled but not completely eliminated by cocultivation with autologous CD8+ T-lymphocytes as measured by limiting dilution nested PCR (NPCR). The expanded cells showed the typical phenotype of highly activated memory type T-lymphocytes (CD3+ CD45RO+ CD25+ HLA-DR+). The distribution of CD4+ and CD8+ T-cells did not reveal significant changes before and after culture indicating that both subsets were equally expanded. Functionally important membrane or intracellular epitopes which were found to be decreased in HIV infected subjects (CD7, CD55, CD59) before culture were reconstituted after ex vivo propagation of T-cells. The functional importance of the up-regulation of complement regulating epitopes (CD55, CD59) after culture could be proven by a significant inhibition of cytolysis of T-cells in the presence of autologous complement. The majority (75%) of expanded CD8+ T-cells stained positive with mAb TIA-1 which is directed to intracellular granules within cytotoxic T-cells. Furthermore, programmed cell death of expanded T-cells could be prevented by cocultivation with fibroblasts which are believed to secrete a cytokine pattern preventing activated T-cells from apoptosis after withdrawal of IL-2 and other stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

From AIDS to parasite infection: pathogen-mediated subversion of programmed cell death as a mechanism for immune dysregulation

Premature cell death can result either from cell injury or degeneration, leading to necrosis, or from the activation of a physiological cell-suicide process, termed programmed cell death or apoptosis, that is regulated by intercellular signalling. This process plays an essential role in the selection of developing lymphocytes, and is also involved in the function of the mature adaptative immune system. A growing number of experimental findings during the last 4 years has provided support to our hypothesis that inappropriate HIV-mediated dysregulation of programmed T-cell death is relevant to AIDS pathogenesis. A series of recent experimental results also supports the general concept that the persistence and pathogenesis of several infectious pathogens, ranging from retroviruses to parasites, may be related to their capacity to dysregulate programmed cell death in various cell populations including lymphocytes. Subversion by pathogens of the physiological control of programmed cell death provides a paradigm for the pathogenesis of a wide range of infectious diseases that involve immune dysregulation and suggests therapeutic potential for the in vivo modulation of cell signalling.

Clinical significance of in vitro donor-specific hyporesponsiveness in renal allograft recipients as demonstrated by the MLR

A longitudinal study was carried out on 19 recipients of cadaveric renal allografts, monitoring their anti-donor and anti-third party responses in the mixed lymphocyte reaction (MLR) at the time of transplantation and at 3, 6, and 12 months post-transplant. Two patterns of responses were identified: in the first (n = 11), patients showed, or later developed, donor-specific hyporesponsiveness, and in the second (n = 8), patients had persistent antidonor and anti-third party responses. After 1 year, the serum creatinine, number of episodes of acute rejection and biopsy findings were compared in both groups. In the first group, the mean serum creatinine was 136.4 mmol/l, the total number of acute rejection episodes was three and in nine of the ten available biopsies, there were minimal cellular infiltrates and normal appearance of the glomeruli, tubules and blood vessels. In the second group, the mean serum creatinine was 163 mmol/l, the total number of acute rejection episodes was 12 and in five of the seven biopsies available, evidence of ongoing rejection was obtained. The difference in mean serum creatinine was not statistically significant (P > 0.05), but the difference in the numbers of acute rejection episodes was (P < 0.05). It is concluded that in some renal allograft recipients, a state of donor-specific hyporesponsiveness develops, and this state may be associated with better graft outcome at 1 year. These data may be useful in selecting patients for reduced immunosuppressive therapy.

Distribution of equid herpesvirus-1 (EHV-1) in respiratory tract associated lymphoid tissue: implications for cellular immunity

Twelve adult ponies and 2 conventional foals were exposed intranasally to EHV-1, strain Ab4 (TCID50 10(-6.6) and samples of respiratory tract associated lymphoid tissues were recovered between 12 h and 13 days after infection. Infectious virus was detected in tissue homogenates using susceptible cell monolayers and expression of viral antigens was monitored using indirect immunoperoxidase histochemistry on paraffin sections. The results showed both infectious EHV-1 and viral antigens in respiratory tract associated lymph nodes 12 h after exposure. Infected leucocytes were identified morphologically as lymphocytes, monocytes, macrophages and plasma cells. The rapid intracellular localisation of EHV-1 in lymph nodes implies that cell mediated immunity is an important aspect of the equine response to this virus.

Viral DNA burden and decline in percentage of CD4-positive cells in the lymphoid compartment of SIV-infected macaques

The decline in CD4+ cells and increased viral DNA and RNA burden in the blood of human immunodeficiency virus (HIV)-infected individuals have been used as closely related correlates of disease progression. However, little is known about levels of total or unintegrated viral DNA in lymphoid tissue of HIV-infected patients and how they relate to CD4+ cell decline or disease progression. Exploiting the similarities between HIV- and simian immunodeficiency virus (SIV)-induced disease, we examined lymphoid organs and peripheral blood from SIV-infected macaques for total (pol) and unintegrated 2-LTR circular viral DNA by polymerase chain reaction (PCR). Two SIV isolates (SIVmac/251 and SIVmne/E11S) that differ markedly in their biological and clinical properties were studied. The results indicate that total viral DNA burdens vary considerably between isolates. There was no strong association between total viral DNA levels and CD4% in lymphoid tissues when isolates were compared and death was not associated with any particular level of viral pol DNA. In contrast, accumulation of unintegrated viral DNA was closely associated with decline in CD4/CD8 ratios in lymphoid organs and AIDS. The appearance of both pol and unintegrated viral DNA in thymus of infected macaques also emerged as one of the single best correlates or possible predictors of advanced disease yet studied. Their roles in pathogenesis are discussed.

Programmed cell death and AIDS: significance of T-cell apoptosis in pathogenic and nonpathogenic primate lentiviral infections

We have proposed that inappropriate induction of programmed cell death (PCD) or apoptosis, a physiological cell-suicide process, may play a role in the pathogenesis of AIDS. This model has been supported by several reports of abnormal levels of PCD in vitro in both CD4+ and CD8+ T cells from human immunodeficiency virus type 1 (HIV-1)-infected persons. To further assess the significance of such a process in AIDS pathogenesis, in vitro PCD was compared in HIV-1-infected persons and in various primate models that allow discrimination between pathogenic chronic lentiviral infection either in the same species, such as rhesus macaques infected with different simian immunodeficiency viruses (SIV), or in different species, such as SIV-infected African green monkeys and HIV-1-infected chimpanzees. Abnormal levels of PCD in CD4(+)-T-cell-depleted peripheral blood mononuclear cells (PBMC), containing the CD8+ T cells, were observed in both pathogenic and nonpathogenic models. However, abnormal levels of PCD in the CD8(+)-T-cell-depleted PBMC, containing the CD4+ T cells, was only observed in the two models leading to AIDS: HIV-1-infected persons and rhesus macaques infected with a pathogenic strain of SIV. This suggests that inappropriate T-cell PCD in HIV-1-infected persons involves two distinct processes: one, concerning CD4+ T cells, is closely related to AIDS pathogenesis; and the other, concerning CD8+ T cells, may be a consequence of immune stimulation with no direct link to AIDS pathogenesis.

Recovery of T-lymphocytes for adoptive immunotherapy by lymphapheresis of HIV-infected patients without alterations of virological, immunological or clinical parameters

We performed repeated continuous flow cytaphereses (CFC) on 13 asymptomatic HIV-1-infected patients to study the feasibility of cell separation procedures to recover high yields of peripheral blood T-lymphocytes for adoptive immunotherapy in HIV-infected patients and to determine immunological and virological alterations following such procedures. A mean yield of 6.23 x 10(9) lymphocytes could be obtained by each cytapheresis, containing 1.82 x 10(9) CD4+, 3.23 x 10(9) CD8+ T-lymphocytes and 8.39 x 10(6) CD34+ peripheral progenitor cells. The CD4/CD8 ratio (mean 0.53, SD +/- 0.15) in the cell samples reflected the distribution of the lymphocyte subsets in vivo. Absolute lymphocyte counts decreased at a mean of 404/mm3 (25%) immediately after CFC but were replaced from the extravascular pool within 1 h. The CD4/CD8 ratios, p24-antigenaemia, HLA-DR expression and neopterin levels did not change significantly after cell separation. No alteration of the number of T-cells with integrated proviral DNA copies (1/10(3) to 1/10(6)) could be detected in peripheral T-helper cells by PCR after lymphapheresis. We conclude that high yields of peripheral T-lymphocytes can be obtained by continuous flow lymphapheresis for cell-mediated immunotherapy, without deterioration of virological or immunological parameters in HIV-infected patients. The separated T-cells are fully replaced from extravascular pools after 1 h.

Functional defects in peripheral blood T cells of multiple sclerosis patients. Diminished in vitro responsiveness in accessory cell dependent activation systems

Function and phenotype of peripheral blood (PB) T cells in multiple sclerosis (MS) patients were analyzed. In whole blood cultures, T cell proliferation of multiple sclerosis (MS) patients, using soluble CD3 mAb and CD2 mAb as stimulants, was reduced in comparison to healthy controls. A similar difference was seen when isolated PBMC were tested after stimulation with soluble CD3 mAb. However, in accessory cell-independent activation systems, i.e. after stimulation of PBMC with immobilized CD3 mAb or after co-stimulation with CD28 mAb, both patients and controls responded equally well. Phenotypical analysis of the circulating T cell population showed that there were no differences in the percentage of CD26+, 'memory' (CD45R0+) or 'effector' (CD4+CD45R0+CD27-) cells between MS patients and healthy controls. Finally, although MS patients did show an enhanced proportion of 'naive' (CD4+CD45RA+) T cells, this did not correlate with the observed functional defects.

B- and T-lymphocyte subset numbers in the migrating lymphocyte pool of the rat: the influence of interferon-gamma on its mobilization monitored through blood and lymph

The subset composition of the migrating lymphocyte pool is largely unknown. In order to determine the number of B, T, CD8+, CD4+ and CD4+ 'naive' (CD45RC+) and 'memory' (CD45RC-) lymphocytes in this pool, the thoracic duct lymph of the rat was drained for 7 days. The effect of lymphocyte depletion on the number of blood lymphocytes was also monitored. In addition, the influence of continuously applied interferon-gamma (IFN-gamma) on the mobilization of the migrating lymphocyte pool was investigated. Within 1 week 2 x 10(9) thoracic duct lymphocytes (TDL) were collected, which represents about 50% of the total lymphocyte pool of an adult rat. Among the migrating lymphocytes an early and a late mobilized population could be differentiated. In the former the CD4+ 'naive' (CD45RC+) T lymphocytes constituted the largest population, whereas in the latter it was the B lymphocytes. Continuous infusion of IFN-gamma did not affect the number of lymphocytes in the blood. In contrast, in the thoracic duct IFN-gamma reduced the appearance of all lymphocyte subsets. However, the pattern of reduction over time differed markedly depending on the population (early or late mobilized) and the phenotype (B- or T-lymphocyte subsets). Thus, the migrating lymphocyte pool of the rat is very heterogeneous regarding its populations and shows complex changes in the mobilization pattern after IFN-gamma stimulation. Future studies should focus on how the size and the composition of the migrating lymphocyte pool is regulated.

Defective T cell receptor/CD3 complex signaling in human type I diabetes

The autoimmune process leading to the destruction of pancreatic beta-cells is mediated by T lymphocytes. Peripheral T cells from subjects with preclinical and clinical type I diabetes respond weakly in vitro to lectin stimulation. We, therefore, investigated in a group of newly diagnosed diabetic patients the presence of a defect in the signal transduction pathway of the T cell receptor (TcR)/CD3 complex. Following stimulation with anti-CD3-coupled beads, the proliferative response in diabetic T cells was significantly decreased in comparison with that from normal T cells. Interestingly, addition of either recombinant interleukin (IL)-2 or phorbol 12-myristate 13-acetate to the cell culture was able to completely restore impaired anti-CD3-induced proliferation in diabetic T cells, suggesting the presence of a defect through the TcR/CD3 pathway, located upstream of protein kinase C (PKC) activation and resulting in low IL-2 production and proliferation. Intracellular Ca2+ measurements by Fluo-3 labeling and flow cytometry analysis on diabetic and control T cells after anti-CD3 stimulation gave comparable results, indicating that this defect does not involve events leading to intracellular Ca2+ mobilization. In contrast, anti-CD3 stimulation of diabetic T cells resulted in a marked impairment of PKC translocation and CD69 antigen expression, as assessed by peptide substrate phosphorylation and by flow cytometry analysis, respectively. Taken together, our data clearly show the presence in individuals at the onset of the disease of an in vitro defect in the signal transduction pathway of the TcR/CD3 complex, resulting in ineffective PKC activation which is not able to induce normal IL-2 production and proliferation of diabetic T cells.

Adrenaline-induced leucocytosis: recruitment of blood cells from rat spleen, bone marrow and lymphatics

It is well known that adrenaline causes leucocytosis, but the sources and the mechanisms of this have not been clarified. We investigated the contributions of subpopulations of white blood cells to this leucocytosis and the importance of the spleen, bone marrow and lymphatics in releasing leucocytes into the blood stream following an injection of adrenaline. We studied possible effects of adrenaline on blood flow to the spleen and bone marrow to see if any contribution to leucocytosis from these organs could be perfusion dependent. In intact awake rats, total blood leucocytes increased within 5 min to about 220% of baseline concentration, the increases of lymphocytes and neutrophilic granulocytes being about 250% and 160%, respectively. The T and B lymphocytes and natural killer cells were all mobilized, to about 230% to 250% of baseline concentrations. The leucocytosis was short-lasting, so that the cell concentrations returned to baseline within 25 min after adrenaline injection. The bone marrow, spleen, and efferent lymphatics all contributed substantially to this leucocytosis, since band-nucleated granulocytes increased upon adrenaline injection, and splenectomized or thoracic duct drained rats showed a markedly reduced leucocytosis in response to adrenaline. Supplementary data were obtained with bone marrow depleted (with 89Sr irradiation) rats. The release of leucocytes from these organs was apparently not blood-flow dependent in the control rats since organ perfusion remained unaltered after adrenaline injection. Adrenaline was found to stimulate the release of both mono- and polymorphonuclear cells in the awake rat and the release of leucocytes from the spleen, bone marrow and efferent lymphatics to contribute significantly to the leucocytosis.

Changes in peripheral blood lymphocyte subset frequencies in myasthenia gravis patients are related to immunosuppression

Surface antigens on peripheral blood lymphocytes from myasthenia gravis patients were investigated. The expression of DR+ and CD8+/DR+ T lymphocytes was increased and the expression of CD4+ T cells reduced. Neither thymectomy, clinical condition nor anti-acetylcholine receptor antibody titre correlated with any of the changes in peripheral blood lymphocyte subsets observed. However, immunosuppressive therapy correlated with the significant reduction in CD4+ and CD2+/CD4+ T cells in these patients.

Effect of high-dose steroid therapy on T-cell subpopulations. A longitudinal study in MS patients

Lymphocyte subpopulations, T cell activation antigens, and serum levels of interleukin 2 (IL-2) and soluble IL-2 receptor (sIL2R), were studied in relapsing-remitting MS (RR-MS) patients before and after high-dose steroid therapy. Prior to therapy, a minority of patients showed increased HLA-DR antigen expression, and an increased number of CD16+ and CD19+ cells. Steroid treatment induced a significant increase in HLA-DR and CD19 expression, a significant reduction in CD16+, CD57+, and CD8+ CD57+ cells, and a slight, non-significant, decrease in IL-2 and sIL-2R levels and CD25 expression on CD4+ T lymphocytes.

Immunological effects of acute and chronic nicotine administration in rats

We previously demonstrated that acute nicotine administration decreased the response of rat blood leukocytes (PBL) to concanavalin A (ConA). We now extend those findings to a comparison between the effects of acute and prolonged nicotine exposure (ten daily injections), on PBL and splenocytes (SL). A single injection suppressed the PBL response to ConA and phytohemagglutinin (PHA); tolerance developed by ten injections. In contrast, acute nicotine did not affect SL response to ConA and reduced the PHA response only at the highest concentration. Ten nicotine injections enhanced SL responsiveness to PHA. The only change in PBL subsets was an increase in CD8+ cells following ten injections.

Flow cytometric analysis of peripheral blood lymphocyte immunophenotypes in persons infected with Treponema pallidum

To characterize the human immune response to syphilis, we determined the effect of infection with Treponema pallidum on the percentage of the various lymphocyte subpopulations in the peripheral blood of infected and uninfected persons. Monoclonal antibodies labeled with either fluorescein isothiocyanate or phycoerythrin were used to perform dual color analysis on a FACScan with the following markers: CD3 for total T cells, CD4 for T helper cells, CD8 for T suppressor cells, CD19 for B cells, and CD16 plus CD56 for natural killer cells. Lymphocyte immunophenotype results were analyzed by the stage of untreated syphilis and by gender. Although they were within the ranges of the normal distribution of immunophenotypes, the percentages of CD4+ cells were significantly lower (P < 0.001) and those of CD8+ cells were higher (P = 0.03) in patients with syphilis than in the uninfected population. For infected versus uninfected subjects, both women and men, the differences in the mean percentages of CD3+ and CD4+ cells were significant (P < or = 0.05). Significant differences were noted between the sexes in secondary syphilis only in the mean percentages of cells positive for CD3, CD4, CD8, and CD16 plus CD56. Gender had no effect on lymphocyte subpopulations in subjects with primary or latent syphilis. In the control population, significant differences due to gender were observed in the percentages of cells positive for CD3, CD4, and CD16 plus CD56.

T cell-dependent activity of ganglioside GM1-specific B cells in Guillain-Barré syndrome and multifocal motor neuropathy in vitro

Synthesis of anti-ganglioside GM1 antibodies of the IgM class by peripheral blood mononuclear cells (PBMNC) from patients with immune-mediated neuropathies and motor neuron diseases and from normal controls was stimulated by Pokeweed mitogen (PWM) in vitro. In patients with acute Guillain-Barré syndrome or multifocal motor neuropathy and high serum titers of IgM anti-ganglioside GM1 antibodies this culture response was greatly enhanced as compared to controls and already detectable in unstimulated cultures. Limiting dilution analysis demonstrated high frequencies of GM1-specific B cells in these patients. Anti-ganglioside GM1 antibodies of the IgG and IgA class were only produced by PBMNC from patients with Guillain-Barré syndrome corresponding to serum titers. In cultures taken at intervals over 6 months in vitro B cell activity for IgM, IgG and IgA anti-ganglioside GM1 antibodies in two Guillain-Barré syndrome patients declined accompanied by clinical improvement and falling serum titers. We conclude that GM1-specific PWM-responsive B cells pre-exist in peripheral blood and respond to T cell-dependent stimulation in Guillain-Barré syndrome and multifocal motor neuropathy.

Circulating leucocyte subpopulations in sedentary subjects following graded maximal exercise with hypoxia

Ten healthy sedentary subjects [age, 27.5 (SD 3.5) years; height, 180 (SD 5) cm; mass, 69.3 (SD 6.3) kg] performed two periods of maximal incremental graded cycle ergometer exercise in a supine position. Randomly ordered and using an open spirometric system, one exercise was carried out during normoxia [maximal oxygen consumption (VO2max) = 38.6 (SD 3.5) ml.min-1.kg-1; maximal blood lactate concentration, 9.86 (SD 1.85) mmol.l-1; test duration, 22.6 (SD 2.7) min], the other during hypoxia [VO2max = 33.2 (SD 3.2) ml.min-1.kg-1; maximal blood lactate concentration, 10.38 (SD 2.02) mmol.l-1; test duration, 19.7 (SD 2.8) min]. At rest, immediately (0 p) and 60 min (60 p) after exercise, counts of leucocyte subpopulations (flow cytometry), cortisol and catecholamine concentrations were determined. At 0 p in contrast to normoxia, during hypoxia there was no significant increase of granulocytes. There were no significant differences between normoxia and hypoxia in the increases from rest to 0 p in counts of monocytes, total lymphocytes and lymphocyte subpopulations [clusters of differentiation (CD), CD3+, CD4+CD45RO-, CD4+CD45RO+, CD8+CD45RO-, CD8+CD45RO+, CD3+HLA-DR+, CD3-CD16/CD56+, CD3+CD16/CD56+, CD19+] as well as adrenaline, noradrenaline and cortisol concentrations. The counts of CD3-CD16/CD56(+)- and CD8+CD45RO(+)-cells increased most. At 60 p, CD3-CD16/CD56+ and CD3+CD16/CD56(+)-cell counts were below pre-exercise levels and under hypoxia slightly but significantly lower than under normoxia. We concluded that the exercise-induced mobilization and redistribution of most leucocyte and lymphocyte subpopulations were unimpaired under acute hypoxia at sea level. Reduced increases of granulocyte counts during the study and reduced cell numbers of natural killer cells and cytotoxic, not major histocompatibility complex-restricted T-cells, only indicated marginal effects on the immune system.