Lymphocyte Surface Antigen Expression Research Articles

Plasmacytoid dendritic cells (pDCs) and IFN-α production in aged squirrel monkeys (Saimiri boliviensis boliviensis) stimulated with Class C CpG Oligodeoxynucleotides

Abstract Synthetic CpG oligodeoxynucleotides (ODNs) with defined CpG motifs and immunomodulatory properties signal through an endosomal membrane-based type of pattern recognition receptor (PRR), the Toll-like receptor 9 (TLR9), that has been identified in dendritic cells (DCs), B cells, and other human immune cell types. CpG-ODNs influence several signaling pathways, leading to cytokine production in many mammalian species that make CpG ODNs suitable as therapeutic interventions in a variety of human disease conditions. The squirrel monkey (SQM), a well-established New World non-human primate (NHP) model is known to be used for studying various diseases such as Alzheimer’s disease (AD), malaria, and transmissible spongiform encephalopathies (Creutzfeldt-Jacob disease). In the present study, we generated the first report of immunoregulatory activity of class C CpG-ODN in aged squirrel monkey. CpG-ODN exhibits very potent effects on squirrel monkey immune cells by inducing IFN-γ/IFN-α from peripheral blood mononuclear cells and demonstrates accelerated kinetics of activity. In addition, class C CpG-ODN specifically activates pDCs to undergo maturation and secrete cytokines, including high levels of IFN-α. To best to our knowledge, this is the first documentation describing immune status in squirrel monkeys immunized with C class CpG-ODN by concentrating on lymphocyte surface antigen expression and function. Overall, our findings provide critical data regarding the immunomodulatory potential of CpG-ODN in this NHP model allowing for future therapeutic trials of innate immunity stimulation via TLR9 agonists for diverse indications including AD therapeutics.

A Canine Model of Chronic Graft-versus-Host Disease

In long-term survivors of allogeneic hematopoietic cell transplantation (HCT), chronic graft-versus-host disease (GVHD) is the major cause of morbidity and mortality and a major determinant of quality of life. Chronic GVHD responds poorly to current immunosuppressive drugs, and while T cell depletion may be preventive, this gain is offset by increased relapse rates. A significant impediment to progress in treating chronic GVHD has been the limitations of existing animal models. The goal of this study was to develop a reproducible comprehensive model of chronic GVHD in the dog. Ten recipient dogs received 920 cGy total body irradiation, infusion of marrow, and an infusion of buffy coat cells from a dog leukocyte antigen (DLA)–mismatched unrelated donor. Postgrafting immunosuppression consisted of methotrexate (days 1, 3, 6, 11) and cyclosporine. The duration of cyclosporine administration was limited to 80 days instead of the clinically used 180 days. This was done to contain costs, as chronic GVHD was expected to develop at earlier time points. All recipients were given ursodiol for liver protection. One dog had graft failure and 9 dogs showed stable engraftment. Eight of the 9 developed de novo chronic GVHD. Dogs progressed with clinical signs of chronic GVHD over a period of 43 to 164 (median, 88) days after discontinuation of cyclosporine. Target organs showed the spectrum of chronic GVHD manifestations that are typically seen clinically. These included lichenoid changes of the skin, fasciitis, ocular involvement (xerophthalmia), conjunctivitis, bronchiolitis obliterans, salivary gland involvement, gingivitis, esophageal involvement, and hepatic involvement. Peripheral blood lymphocyte surface antigen expression of CD28 and inducible costimulator was elevated in dogs with GHVD compared with those in normal dogs, but not significantly so. Serum levels of IL-8 and monocyte chemotactic protein-1 in GVHD-affected dogs at time of euthanasia were elevated, whereas levels of IL-15 were depressed compared with those in normal dogs. Results indicate that the canine model is well suited for future studies aimed at preventing or treating chronic GVHD.

In Vitro Influence of Mycophenolic Acid on Selected Parameters of Stimulated Peripheral Canine Lymphocytes.

Mycophenolic acid (MPA) is an active metabolite of mycophenolate mofetil, a new immunosuppressive drug effective in the treatment of canine autoimmune diseases. The impact of MPA on immunity is ambiguous and its influence on the canine immune system is unknown. The aim of the study was to determine markers of changes in stimulated peripheral canine lymphocytes after treatment with MPA in vitro. Twenty nine healthy dogs were studied. Phenotypic and functional analysis of lymphocytes was performed on peripheral blood mononuclear cells cultured with mitogens and different MPA concentrations– 1 μM (10−3 mol/m3), 10 μM or 100 μM. Apoptotic cells were detected by Annexin V and 7-aminoactinomycin D (7-AAD). The expression of antigens (CD3, CD4, CD8, CD21, CD25, forkhead box P3 [FoxP3] and proliferating cell nuclear antigen [PCNA]) was assessed with monoclonal antibodies. The proliferation indices were analyzed in carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled cells. All analyses were performed using flow cytometry. The influence of MPA on apoptosis was dependent on the mechanism of cell activation and MPA concentration. MPA caused a decrease in the expression of lymphocyte surface antigens, CD3, CD8 and CD25. Its impact on the expression of CD4 and CD21 was negligible. Its negative influence on the expression of FoxP3 was dependent on cell stimulation. MPA inhibited lymphocyte proliferation. In conclusion, MPA inhibited the activity of stimulated canine lymphocytes by blocking lymphocyte activation and proliferation. The influence of MPA on the development of immune tolerance–expansion of Treg cells and lymphocyte apoptosis–was ambiguous and was dependent on the mechanism of cellular activation. The concentration that MPA reaches in the blood may lead to inhibition of the functions of the canine immune system. The applied panel of markers can be used for evaluation of the effects of immunosuppressive compounds in the dog.

Role of FK778 Alone or in Combination with Tacrolimus or mTOR Inhibitors as an Immunomodulator of Immunofunctions: In Vitro Evaluation of T Cell Proliferation and the Expression of Lymphocyte Surface Antigens

We evaluated the in vitro capacity of FK778, alone or in combination with other immunosuppressive drugs: Tacrolimus (TRL); Sirolimus (SRL), Everolimus (EVL), to inhibit clonal expansion of T-lymphocytes and expression of lymphocyte-activation surface antigens; secondly, we compared the immunosuppressive potential of FK778 combined with TRL, SRL and EVL with the same combinations using Mycophenolic acid (MPA) as antimetabolite. Lymphocyte proliferation was assessed by 3H-Thymidine incorporation, in whole blood cultures stimulated with ConA. The effect of FK778 on alloresponse was evaluated by MLC and the expression of lymphocyte surface antigens by cytometry. FK778, TRL, SRL and EVL showed a high in vitro capacity to inhibit lymphocyte proliferation in a concentration-dependent way. Combinations of FK778 with TRL, SRL, or EVL presented an additive effect, especially FK778+TRL. Similar inhibition capacity of the clonal expansion was observed, when FK778 was combined with TRL, SRL or EVL, respecting the same combinations but using MPA instead of FK778. In addition, FK778 inhibited the expression of lymphocyte surface antigens involved in activation, co-stimulatory and apoptosis signals. In conclusion, FK778 inhibits the proliferative response induced by mitogeneic and allogeneic stimuli and the expression of surface antigens. Combinations of FK778 with TRL or mTOR inhibitors presented an additive effect and their action on T cell proliferation was similar to that of combinations with MPA. Since FK778, TRL and mTOR inhibitors present different action mechanisms and involve different cellular targets, these combinations may help prevent episodes of allorejection in organ transplants. FK778 and mTOR inhibitors may represent an alternative treatment for patients with renal failure.

Impact of Different Cell Isolation Techniques on Lymphocyte Viability and Function

The outcome of immunological assays is markedly influenced by the method of isolation of lymphocytes. It is, therefore, important to comparatively assess various techniques of isolation of lymphocytes, an aspect thus far not thoroughly addressed. In particular, the potential of isolation techniques to influence cell recovery, viability, and function has not yet been evaluated. These studies were designed to determine the effect of different mechanical tissue dissociation methods on the viability and function of lymphocytes. Following spleen and thymus removal, the lymphoid organs were dissociated by one of four different tissue dissociation techniques: metallic screen, sheer force slide, commercial stomacher, or plunger‐screen. Cells were then enumerated and a trypan blue exclusion technique and 7‐amino‐actinomycin D (7‐AAD) were both employed to assess viability. Mitogen‐induced lymphocyte proliferation was measured using the Alamar Blue™ assay. Cell viability and lymphocyte surface antigen expression were assessed using flow cytometry. No significant differences in lymphocyte viability, morphology, or surface antigen expression were observed among the different techniques. Likewise, cellular apoptosis and necrosis were comparable across all the techniques. However, mitogen induced splenic T‐cell proliferation was higher in cells collected using the metallic screen and plunger‐screen isolation methods as compared to the sheer force slide or commercial stomacher procedures. These data suggest that cell recovery, morphology, and viability are not affected by isolation techniques. However, lymphocyte function, as assessed by mitogen induced proliferation, was negatively affected by the sheer force slide or commercial stomacher isolation techniques.

FK778 and Tacrolimus Prevent the Development of Obliterative Airway Disease After Heterotopic Rat Tracheal Transplantation

The effectiveness of the novel immunosuppressive agent FK778 and of tacrolimus to prevent the development of obliterative airway disease (OAD) was investigated in an animal model. Tracheae from Brown-Norway donors were heterotopically transplanted in the greater omentum of Lewis rats. Recipients were treated for 28 days with FK778 (5 or 20 mg/kg), tacrolimus (1 or 4 mg/kg) or combination regimens at varying doses (5 + 1 mg/kg, 10 + 2 mg/kg or 20 + 4 mg/kg). Grafts were harvested and processed for histologic and immunohistochemical evaluation. Lymphocyte surface antigen expression was quantified and in vitro smooth muscle cell (SMC) proliferation assays were performed. In untreated recipients, very large amounts of infiltrating CD4+, CD8+ and ED1+ mononuclear cells were observed in the peritracheal region with epithelial loss and complete luminal obliteration. Granulation tissue consisted of alpha-actin-positive cells and collagen-rich fibrosis. FK778 and tacrolimus as well as combination regimens of both agents dose-dependently inhibited peritracheal infiltration and luminal obliteration. Only tacrolimus-treated recipients showed preserved luminal epithelial coverage with airway goblet cells, whereas, in animals that received FK778, no epithelium was found. Both agents equally suppressed in vivo lymphocyte CD25 expression. Only FK778-treated animals were completely free of adverse drug side effects. FK778 but not tacrolimus showed potent anti-proliferative effects on SMC in vitro. Although both agents proved effective to prevent OAD development, histology revealed major differences. The anti-proliferative potency of FK778 on SMC may be an important mechanism of action. Combination regimens showed favorable drug interaction and allowed dose reduction of both agents to achieve maximal immunosuppressive efficacy.

B- and t-cell markers in opsoclonus-myoclonus syndrome: immunophenotyping of CSF lymphocytes

Although an autoimmune etiology is likely, the pathophysiology of opsoclonus-myoclonus syndrome (OMS) remains poorly understood, and no immunologic abnormalities have correlated with neurologic severity. In addition, conventional immunotherapies often do not prevent relapse or permanent sequelae. In children, neuroblastoma and viral infections are the most common cause. The aim of this study was to test the cellular immune hypothesis of OMS in a cross-sectional study and determine if CSF lymphocyte subset analysis provides biomarkers of disease activity. The expression of lymphocyte surface antigens was investigated in CSF and blood of 36 children with OMS and 18 control subjects, using a comprehensive panel of monoclonal antibodies to adhesion and activation proteins in combination with anti-CD3 and anti-CD45 antibodies in 4-color fluorescence-activated cell sorting. Although most children with OMS had normal CSF cell counts, they exhibited expansion of CD19+ B-cell (up to 29%) and gamma/delta T-cell (up to 26%) subsets and a lower percentage of CD4+ T-cells and CD4/CD8 ratio, which persisted even years after disease onset and conventional treatments. The percentage of activated CSF T-cells was also higher. Abnormalities correlated with neurologic severity, as scored blinded from videotapes using a 12-item motor scale, and disease duration. No significant differences were found between tumor and no-tumor groups. In children with neuroblastoma, tumor resection or cancer chemotherapy did not alter immunologic abnormalities. The authors conclude that CSF B- and T-cell recruitment is linked to neurologic signs in pediatric OMS, which may relate to relapses and disease progression.—Valerie Biousse

B- and T-cell markers in opsoclonus-myoclonus syndrome: immunophenotyping of CSF lymphocytes.

Although many lines of evidence suggest an autoimmune etiology, the pathophysiology of opsoclonus-myoclonus syndrome (OMS) remains poorly understood and no immunologic abnormalities have correlated with neurologic severity. Conventional immunotherapies often do not prevent relapse or permanent sequelae. To test the cellular immune hypothesis of OMS in a cross-sectional study and determine if CSF lymphocyte subset analysis provides biomarkers of disease activity. The expression of lymphocyte surface antigens was investigated in CSF and blood of 36 children with OMS and 18 control subjects, using a comprehensive panel of monoclonal antibodies to adhesion and activation proteins in combination with anti-CD3 and anti-CD45 antibodies in four-color fluorescence-activated cell sorting. Although most children with OMS had normal CSF cell counts, they exhibited expansion of CD19+ B-cell (up to 29%) and gammadelta T-cell (up to 26%) subsets and a lower percentage of CD4+ T-cells and CD4/CD8 ratio, which persisted even years after disease onset and conventional treatments. The percentage of activated CSF T-cells was also higher. Abnormalities correlated with neurologic severity, as scored blinded from videotapes using a 12-item motor scale, and disease duration. No significant differences were found between tumor and no-tumor groups. In children with neuroblastoma, tumor resection or cancer chemotherapy did not alter immunologic abnormalities. CSF B- and T-cell recruitment is linked to neurologic signs in pediatric OMS, which may relate to relapses and disease progression.

Lymphocyte subpopulations in pregnancy complicated by hypertension

The immune responsiveness of women is altered during pregnancy in order to retain protective properties against disease and at the same time allow tolerance of the fetus. Diseases such as pre-eclampsia (PE) have been suggested to arise as a result of maladaptations in these immune alterations. Here we evaluate the effect of PE on the composition of peripheral blood lymphocyte subpopulations using lymphocyte surface antigen expression. Fifty-four women of various parities with pregnancy-induced hypertension (PIH) (39 non-proteinuric and 14 proteinuric) and matched controls (30 normotensive pregnant women (NTP) and 15 healthy non-pregnant women (NP)) were investigated. Monoclonal antibodies specific for human T lymphocytes and subpopulations: CD2, CD3, CD4, CD8, CD19 and activation markers: CD25, CD45RA, CD45RO, CD54 AND HLA m DR were used and detected using a two-colour fluorescence analysis with an automated flow cytometer. The total number of T lymphocytes: CD2, CD3, CD4, CD8 and CD19 were significantly decreased in PIH particularly PE ( P <0.05). T cells expressing NK surface markers (CD3/CD16 + CD56) and CD4 cells expressing HLA m DR were higher in PE. CD8 + HLA m DR + cells and T-helper cells expressing adhesion molecules) CD4 + CD54 + ) were higher in NTP than in NP and PE ( P <0.05, 0.05). PE is associated with elevated levels of CD4 + HLA m DR + , and CD3 + NK cells but decreased total numbers of T lymphocytes, and the CD3 + CD25 + subpopulation. These findings indicate systemic alterations in maternal immunity associated with the PE state. This feature of the disease may contribute to abnormal adaptation to pregnancy resulting in PE and PIH, promoting adverse outcomes including pregnancy loss.

The expression of lymphocyte surface antigens in bronchial biopsies, bronchoalveolar lavage cells and blood cells in healthy smoking and never-smoking men, 60 years old

In this study we investigated if smoking subjects with a normal or slightly decreased lung function differ in the lymphocyte pattern compared to never-smokers.In a group of ‘healthy’ smokers (n=58) and never-smokers (n=34) 60 years old, we investigated the lymphocyte pattern in both BAL (n=30 and n=18 respectively), bronchial epithelium and lamina propria (n=14 andn =10 respectively) and blood.We found that all subjects, despite smoking history, had a higher number of CD8+ cells per mm2in the epithelium compared to the lamina propria in the bronchial biopsies. In smokers, these CD8+ cells were significantly negatively correlated to FEV1(r=−0·56,P =0·04). In smokers, the number of CD8+ lymphocytes was higher and the T cell activation markers (CD57+ and CD28+) were lower in BAL, than in never-smokers. This last finding was also seen in blood for CD3+57+.We conclude, that in ‘healthy’ smokers the lymphocyte patterns are different compared to never-smokers, to some extent in BAL. There is also a relation between lymphocytes in the bronchial mucosa and lung function. This has previously been shown in patients with chronic obstructive pulmonary disease (COPD) and chronic bronchitis but not in asymptomatic smokers.

New monoclonal antibody diagnostic reagents for type I diabetes: differential lymphocyte surface antigen expression related to disease.

New cellular-based reagents are needed to diagnose type I diabetes as well as to monitor the outcomes of clinical trials at early time points. Four new monoclonal antibodies (mAbs) have been shown to demonstrate reduced binding to lymphocytes from identical twins with long-term type I diabetes relative to that observed with lymphocytes from their twin partners without diabetes or from control subjects. Biochemical analysis revealed mAb 3G12EG recognized an unidentified 45-kDa protein, whereas mAb 2E8F1 and 5B6E11 did not appear to precipitate specific proteins as detected by SDS-PAGE. Electrophoresis under reducing and nonreducing conditions and peptide mapping revealed that mAb 8F410 recognizes a novel dimeric form of HLA class I molecule. Predictions from crystallography studies suggested previously this class I dimer as the optimal activation of a single CD8 T-cell. In B-cells from both normal and diabetic individuals, the class I dimer was minimally associated with beta2-microglobulin rapidly formed in the endoplasmic reticulum. These new reagents appear to be able to identify new lymphocyte surface phenotypes associated with diabetes expression in both fresh blood samples and Epstein-Barr virus-established cell lines.

New monoclonal antibody diagnostic reagents for type I diabetes: differential lymphocyte surface antigen expression related to disease

New monoclonal antibody diagnostic reagents for type I diabetes: differential lymphocyte surface antigen expression related to disease

Abnormal lymphocyte surface antigen expression in peripheral blood of a Kuwaiti population.

Abnormal lymphocyte surface antigen expression in peripheral blood of a Kuwaiti population.

In vitro assessment of lymphocytes response following re-exposure to silicone

Currently, the use of silicone-filled devices, mainly in plastic surgery for breast reconstruction or augmentation, is being debated by the scientific community in connection with the risk to the patient. In this study the response of whole blood or isolated peripheral blood lymphocytes from patients with silicone-gel-filled breast implants was assessed in vitro, in order to verify the hypothesis of silicone material acting in vivo as a sensitizing agent. Both quantitative and qualitative changes of lymphocyte subpopulations of patients carrying silicone devices were assessed and compared with healthy subjects. Upon 24–72 h in vitro re-exposure of patients' lymphocytes to silicone extract, lymphocyte surface antigen expression was monitored by flow cytometry, and the functional response of lymphocytes was measured by radioactive tracer uptake and biochemical changes.

Surgical influence on murine immunity and tumor growth: relationship of body temperature and hormones with splenocytes.

Adrenalectomy predisposed the C3HeB/FeJ Mouse to tumor from a low dose of tumor cells, derived from a C3H spontaneous mammary adenocarcinoma. Sham surgery had a similar effect. In contrast, ovariectomized females, intact females, and male mice did not allow the low dose of cells to develop into a tumor. In order to better understand the role of hormones on the immune system controlling tumor growth, normal C3HeB/FeJ mice were studied for the effect of corticosterone or estradiol on splenic lymphocyte surface antigen expression. Adrenalectomy and ovariectomy caused a decrease in the percentage of all T cell subclasses and an increase in absolute numbers of immunoglobulin-bearing cells. Reconstitution of ovariectomized mice with estradiol did not significantly alter lymphocyte cell surface antigen expression. In contrast, injection of corticosterone into adrenalectomized mice brought these values to normal. Further study on normal mice placed on a 12:12-hr light:dark schedule showed that the hours after lights on (HALO) had a significant effect (analysis of variance) on body temperature, percentage of splenic B cells, T pan, T helper and T suppressor cells, and absolute numbers of T pan cells. Brain dehydroepiandrosterone sulfate correlated positively with T pan lymphocytes, but showed no significant effect on HALO. In contrast, body temperature showed a strong circadian rhythm (P less than 0.001). In addition, the presentation of estrus was circadian rhythmic (P = 0.003) with 58% of mice in estrus at 16 HALO and only 8% at 4 HALO. Multiple regression analysis revealed body temperature was strongly associated with absolute numbers of splenic T lymphocytes and their subsets, as well as percentage of B lymphocytes, Thy 1.2-, and Lyt-2-bearing cells. Similarly, HALO and estrous cycle stage were associated with percentage of T helper cells. The data showed that body temperature and hormones were associated with the cell surface antigens on lymphocytes and suggest that they affect lymphocyte function.

Differential effects of eight metal ions on lymphocyte differentiation antigens in vitro

In vitro studies were conducted to determine the effects of metal ions known to be released from metallic implants in vivo on the expression of lymphocyte surface antigens. Normal human peripheral blood lymphocytes were exposed to various concentrations of metal ions (Fe3+, Ni2+, Co2+, Mo6+, V5+, Cr6+, Cr3+, and Ti3+) for 30 min at 37 degrees C in a 5% CO2 atmosphere, and then analyzed for their ability to form rosettes with sheep red blood cells. Following this preliminary analysis, lymphocytes were exposed to the metal ions found to inhibit the E-rosette reaction (Fe3+, Ni2+, and Co2+) in order to determine which of the following surface antigens were affected: CD2, CD3, CD4, CD8, CD1, CD22, CD10, and HLA-DR. Our results showed that the in vitro treatment of lymphocytes with Fe3+ or Co2+ caused inhibition of CD2 only, whereas Ni2+ caused inhibition of both CD2 and CD3 antigens. These findings suggest that Fe3+, Co2+, and Ni2+ ions may interfere with T cell activation since both CD2 and CD3 are involved in that process.

Effect of Treatment with Biosynthetic Human Growth Hormone (GH) on Peripheral Blood Lymphocyte Populations and Function in Growth Hormone-Deficient Children

GH influences the immune response. The mechanism is not known; however, the presence of receptors for GH on human lymphocytes as well as its ability to influence and modulate immune responses in animals suggest an association between GH and immune function in man. We evaluated the effect of recombinantly derived natural sequence human GH (hGH) on lymphocyte surface antigen expression, response to mitogenic stimulation, expression of interleukin-1 receptors, and production of anti-hGH antibodies in GH-deficient children. The only observed changes were a decrease in the percentage of B-cells and a transient increased reactivity to phytohemagglutinin stimulation. It appears from the results of our studies that the administration of hGH has a selective effect on lymphocyte immune function; however, we cannot eliminate a role for hGH in the initiation or regulation of antigen-mediated immune responses.

The biological basis for clinical use of interferon

Interferons represent the body's most rapid defence against virus infection. Natural recovery from viral infections is correlated with interferon production; the inhibition of interferon enhances the severity of infection and interferon has been shown to protect animals from some viral infections. beta-Interferon is produced by fibroblasts in response to viral infection. Leucocyte (a) interferon may be induced by foreign or infected cells or by viruses, and it is continuously released into the bloodstream during infection, declining with time. gamma-Interferon are produced later in viral infection by virus-sensitized T lymphocytes. The antiviral action of interferon is induced by interaction with specific receptors on cell surfaces leading to translation of antiviral proteins. Interferons may also enhance immune responses by increasing expression of lymphocyte surface antigens and by increasing the cytotoxic activity of natural killer cells. In chronic hepatitis B and C, it seems likely that interferon's antiviral activity is responsible for the early fall of viral products, while its immunomodulatory activity is responsible for long-term effects, including the destruction of infected hepatocytes, with persistent loss of viral antigens and seroconversion.

Suppression of Cellular Immune Activity Following Severe Head Injury

Infection is a major cause of morbidity following multiple traumatic and head injury. Although immunosuppression has been demonstrated after multiple traumatic injury, the effects of head injury on immune function have not been thoroughly investigated. In a prospective study of 10 severely head-injured patients, in vitro and in vivo parameters of cellular immune activity were assessed. In vitro measurements of lymphocyte surface antigen expression following mitogen stimulation were made serially over a 3-week period in 10 patients with severe head injury. The control group consisted of 20 healthy subjects. Phenotyping of peripheral blood lymphocytes (PBLs) was performed following incubation with and without mitogens. Phenotypes were determined by flow cytometry using monoclonal antibodies (MABs) to T lymphocyte subsets and the alpha subunit of interleukin 2 (IL-2) receptors. In vivo cellular immune function was determined by measuring patient responses to delayed-type hypersensitivity (DTH) skin testing within 24 h of injury. When head-injured patients were compared to controls, PBLs incubated in the presence of phytohemagglutinin (PHA) demonstrated a decrease in cells marking as T cells (p = 0.005), helper-inducer T cells (p = 0.001), and in the number of IL-2 receptor-bearing cells (p = 0.001). The functional ability of these lymphocyte subpopulations to proliferate in the presence of PHA was significantly suppressed within 24 h of injury and normalized within 3 weeks of injury. DTH skin testing to Candida, mumps, trichophyton, and PPD antigens was performed within 24 h of injury and resulted in anergic responses in all 10 patients when measured at 24, 48, and 72 h following administration. The overall infection rate was 60%, with the majority of infections occurring within the first 4 days following injury. The results of this study indicate that severe head injury results in suppression of cellular immune function with a corresponding high rate of infection. The possible significance of the decrease in the percentage of helper-inducer T cells and in the number of cells bearing IL-2 receptors following mitogen stimulation is discussed.

Analysis of Lymphocyte Surface Antigen Expression by the Use of Variant Cell Lines

Distinct cell types arising within the same organism show both qualitative and quantitative differences in the cell-surface molecules they express (Boyse and Old 1969; Schlesinger 1970; Bennett et al. 1972). A paradigmatic example of this are the cells of the lymphoid system, in which a number of molecules specific to cells in various stages of differentiation can be identified immunologically (Boyse and Old 1969; McKenzie and Snell 1975; Trowbridge et al. 1975a; Cantor and Boyse 1975). Since all of the cells of the lymphoid system arise from a common stem cell (Wu et al. 1968), there must exist a network of structural and regulatory genes that interact during lymphocyte differentiation to produce the surface phenotype characteristic of cells in a particular stage along their pathway of differentiation.