Lymphocyte subsets in healthy adult Kuwaiti Arabs with relative benign ethnic neutropenia

Relative and absolute neutropenia is frequently seen in the healthy adult Kuwaiti Arab population. Fluorescent monoclonal antibody labelling followed by flow cytometry was used to determine the lymphocyte subsets in 48 normal healthy individuals in the Kuwaiti adult population (24 males and 24 females, age 17-59 years) with relative or absolute neutropenia, and this was compared to age-matched controls (64 males and 63 females). The mean haemoglobin levels were 13.6+/-1.5 and 13.7+/-1.5 g/dl in the neutropenic and control groups, respectively. White blood cell counts, absolute neutrophil and lymphocyte counts in neutropenic individuals with the corresponding reference range, taken from the control subjects (in parenthesis) were: WBC, 6.7+/-1.6 x 10(9)/l (4-10.4 x 10(9)/l), neutrophils, 2.7+/-0.8 x 10(9)/l (1.87-6.63 x 10(9)/l), lymphocytes, 3.3+/-0.9 x 10(9)/l (1.4-3.62 x 10(9)/l). Absolute values of lymphocytes, CD2+, CD3+, CD19+, CD4+, CD8+, HLADR+ and CD45RA+ cells were significantly higher in the neutropenic group. The range of values with the corresponding reference ranges, in parenthesis, were: CD2+, 1.61-4.30 x 10(9)/l (0.95-2.99 x 10(9)/l), CD3+, 1.37-4.16 x 10(9)/l (0.83-2.71 x 10(9)/l), CD19+, 0.16-1.09 x 10(9)/l (0.05-0.61 x 10(9)/l), CD4+, 0.70-2.89 x 10(9)/l (0.45-1.65 x 10(9)/l), CD8+, 0.57-1.80 x 10(9)/l (0.29-1.17 x 10(9)/l), HLADR+ 0.27-1.74 x 10(9)/l (0.02-0.62 x 10(9)/l), CD45RA, 0.90-4.63 x 10(9)/l (0.34-2.05 x 10(9)/l), respectively. The levels of natural killer cells, CD56+ cells were significantly lower compared to controls while the values of memory T lymphocytes, CD45RO+ were comparable to controls. These results indicate that difference in the leukocyte subpopulations may also be indicative of differences in the lymphocyte subpopulations and that reference ranges for these cell types in healthy neutropenic and non-neutropenic individuals should be established.     

Role of NK cells and gamma interferon in transplacental passage of Toxoplasma gondii in a mouse model of primary infection

Protective immunity in mice infected with Toxoplasma gondii is mainly mediated by NK cells, CD4 and CD8 T cells, and type 1 cytokines, such as gamma interferon (IFN-gamma). To clarify the roles of NK cells and IFN-gamma in protection against primary congenital toxoplasmosis, we used recombination activating gene 2 knockout (RAG-2(-/-)) mice, which lack T and B lymphocytes, in comparison with the wild-type BALB/c model. RAG-2(-/-) mice had a significantly lower risk of fetal toxoplasmosis than BALB/c mice (25 versus 63.9%; P = 0.003). This protection was associated with an increased number of maternal NK cells, IFN-gamma secretion by spleen cells, and decreased parasitemia. In the RAG-2(-/-) mice, NK cell depletion increased both the rate of fetal infection, to 56.5% (P = 0.02), and the blood parasite burden. Conversely, in the BALB/c mice, this treatment did not modify maternofetal transmission or the blood parasite burden. Neutralization of IFN-gamma in both infected RAG-2(-/-) and BALB/c mice decreased congenital Toxoplasma transmission, contrasting with an exacerbation of maternal infection. These data suggest that a partially protective immunity against congenital toxoplasmosis is achieved due to the increased number of NK cells in RAG-2(-/-) mice. However, it seems that IFN-gamma enhances, directly or indirectly, the transplacental transmission.     

CD154-dependent priming of diabetogenic CD4(+) T cells dissociated from activation of antigen-presenting cells

We followed the fate of K(d)- or I-A(g7)-restricted beta cell-autoreactive T cells in monoclonal TCR-transgenic NOD mice expressing or lacking CD154. 8.3-NOD.RAG-2(-/-)/CD154(-/-) mice, which bear autoreactive CD8(+) T cells, developed diabetes with the same incidence and tempo as 8.3-NOD.RAG-2(-/-)/CD154(+) mice. Recruitment of CD154(-/-) 8.3-CD8(+) CTL was accelerated by CD154(+)CD4(+) T cells, by expression of a B7.1 transgene in beta cells or by treatment of the mice with CpG-DNA or an agonistic anti-CD40 antibody. In contrast, the autoreactive CD4(+) T cells maturing in 4.1-NOD.RAG-2(-/-) mice lost their diabetogenic potential if they lacked CD154, even in the presence of CD154(+)CD4(+) T cells, B7.1 molecules on beta cells, CpG-DNA treatment, or systemic CD40 ligation. These results demonstrate the existence of a novel, CD154-dependent pathway of CD4(+) T cell activation that is independent of CD40-mediated activation of APCs.     

Increased susceptibility of RAG-2 SCID mice to dissemination of endodontic infections.

Specific immunity has been implicated in the pathogenesis of periapical lesions, although the extent to which these mechanisms are actually involved in either protection or destruction of the pulp-periapex complex is yet to be established. To investigate this question we compared periapical-lesion pathogenesis in RAG-2 severe combined immunodeficient (SCID) mice with immunocompetent control mice following surgical pulp exposure. In order to equalize the bacterial challenge, an infection protocol using Prevotella intermedia, Fusobacterium nucleatum, Peptostreptococcus micros, and Streptococcus intermedius was devised. The results demonstrated that after infection, the proportion of the root canal flora represented by the four pathogens was almost identical in both groups (39.9 and 42.2% for RAG-2 and immunocompetent control mice, respectively). The effects of abrogation of T- and B-cell mechanisms on periapical pathogenesis were then assessed. Approximately one-third of the RAG-2 mice developed endodontic abscesses, while no immunocompetent controls had abscesses, results which indicated regional dissemination of the infection. A similar incidence of abscesses was found in two additional experiments. Abscessed RAG-2 teeth had significantly larger periapical lesions than did nonabscessed RAG-2 teeth (P < or = 0.05) and exposed immunocompetent controls (P < or = 0.01), whereas nonabscessed RAG-2 teeth were not significantly different from those of exposed immunocompetent controls in periapical-lesion size. We conclude that B- and T-cell-mediated immunity protects the host from the dissemination of endodontic infections and that RAG-2 mice are more susceptible to infection-induced pulp-periapex destruction.     

Pure CD4+ T lymphocytes fail to protect perorally infected SCID mice from lethal microsporidiosis caused by Encephalitozoon cuniculi

The role of CD4+ and CD8+ T lymphocytes in the protection against intraperitoneally (i.p.) or perorally (p.o.) acquired Encephalitozoon cuniculi (Levaditi et al., C R Soc Biol Paris 89:984–986, 1923) infection was studied by means of reconstitution of severe combined immunodeficiency (SCID) mice with well-defined populations of naive CD8+ or CD4+ T lymphocytes. Adoptive transfer of pure CD8+ T lymphocyte subpopulation protects SCID mice against a lethal microsporidiosis caused by E. cuniculi. The protective effect of CD8+ T lymphocytes is manifested in both i.p. and p.o. infection. On the contrary, the host defense against peroral infection does not require CD8+ T cells. The protective role is not mediated by CD4+ T lymphocytes only. SCID mice reconstitution with pure CD4+ T cell subpopulation led to prolonged survival of perorally infected mice. However, these mice died due to lethal encephalitozoonosis caused by i.p. infection.     

Gut-homing CD4+ T cell receptor αβ+ T cells in the pathogenesis of murine inflammatory bowel disease

We studied which T cell subsets from the gut-associated lymphoid tissue (GALT) can migrate out of the gut mucosa and repopulate GALT compartments of an immunodeficient (semi)syngeneic host. Many distinct lymphocyte subsets were found in GALT of immunocompetent H-2^d (BALB/c, BALB/c^dm2, C. B-17+/+) mice. No antigen receptor-expressing lymphoid cells were found in GALT of congenic C. B-17 scid/scid (scid) mice. The heterotopic transplantation of a full-thickness gut wall graft from the ileum or colon of immunocompetent (C. B-17+/+, BALB/c^dm2) donor mice onto immunodeficient scid mice selectively reconstituted a CD3⁺ T cell receptor αβ⁺ CD4⁺ T cell subset. CD4⁺ cells of this subset expressed the surface phenotype of mucosa-seeking, memory T cells. In the immunodeficient scid host, this gut-derived CD4⁺ T cell subset was found in spleen, peritoneal cavity, mesenteric lymph nodes (LN), epithelial layer and lamina propria of the small and large intestine, but not in peripheral LN. Scid mice heterotopically transplanted with gut from a congenic, immunocompetent donor developed clinical and histological signs of inflammatory bowel disease (IBD). Hence, the selective repopulation of GALT compartments with CD4⁺ T cells from normal GALT plays an essential role in the pathogenesis of IBD in an immunodeficient host.     

Regulatory T cells control autoimmunity following syngeneic bone marrow transplantation

Sublethally irradiated, immunodeficient, C57BL/6 RAG-2 gene-deleted recipient mice reconstituted with T cell-depleted bone marrow (BM) grafts frequently developed diarrhea, lost weight and showed signs of autoimmunity, dying between 4 and 7 weeks after reconstitution. Mice died despite evidence of efficient donor-derived hemato-lymphoid reconstitution, and disease was associated with the presence of IgG anti-nuclear antibodies. Autoimmunity was initiated by T cells, but could be prevented by transfer of naturally arising regulatory T cells. In contrast, lethally irradiated, BM-reconstituted immunocompetent, C57BL/6 mice survived without signs of autoimmunity. Survival of immunocompetent mice was shown to be due to the presence of residual, extra-thymically located, radio-resistant, functional regulatory T cells. The importance of regulatory T cells was further shown by the reduced survival of immunocompetent BM recipients whose CD25+ T cells had been depleted prior to bone marrow transplantation. The implications of these results in the context of syngeneic graft-versus-host disease following BM transplantation are discussed.     

Naturally acquired Pneumocystis carinii pneumonia in gene disruption mutant mice: roles of distinct T-cell populations in infection.

When kept under strict specific-pathogen-free conditions, H-21-Abeta (Abeta(-/-),T-cell receptor beta (TCRbeta(-/-)), and recombinase-activating gene 1 (RAG-1(-/-) gene disruption mutant mice, deficient in conventional CD4+ T cells, TCRalphabeta cells, and all peripheral T and B lymphocytes, respectively, consistently developed lethal Pneumocystis carinii pneumonia through natural infection. The most severe symptoms appeared in RAG-1(-/-) mutants. In contrast, TCRdelta(-/-) and beta2-microglobulin(-/-)(beta2m-/-) mutants, deficient in TCRgammadelta cells and conventional CD8alphabeta+ TCRalphabeta cells, respectively, were fully resistant to infection. Our data indicate not only the insufficiency but also the dispensability of CD8 alphabeta+TCRalphabeta cells and of TCRgammadelta lymphocytes in resistance to P. carinii infection. Under disease conditions, large numbers of unusual single-positive CD4+ and CD8alphabeta+ as well as double-negative TCRgammadelta subpopulations of cells accumulated in lungs of TCRbeta(-/-) mutants. This accumulation was consistently accompanied by a drastic increase in the pulmonary B-cell population. In contrast, CD8alphabeta+ TCR alpha beta cells, but no B cells, appeared in lungs of parasitized Abeta (-/-) mutants. Since lung damage and parasite numbers were less prominent in morbid TCRbeta(-/-) and Abeta(-/-) mutants than in diseased RAG-1(-/-) mice, the remaining lymphocytes accumulating in lungs of the former two mutants seem to perform residual resistance functions.     

冬虫夏草提取液对实验性病毒性心肌炎小鼠免疫功能的影响

目的了解早期应用冬虫夏草提取液(CSAE)治疗对病毒性心肌炎(VMC)小鼠心肌病变、血清IFN-γ水平及脾脏T细胞亚群的影响。方法100只成年雄性BALB/c小鼠随机分为正常对照组(CG)、感染组(IG)和CSAE治疗组(CTG)。IG及CTG小鼠腹腔感染柯萨奇病毒B3(CVB3),于感染CVB3后第7天和第14天,计算小鼠的生存率,然后并分批处死,观察心肌组织的病理变化及用ELISA法检测血清IFN-γ的水平。用流式细胞术分析脾脏中CD3 、CD4 、CD8 T细胞的百分率。结果与CG组相比较,IG小鼠血清IFN-γ的水平及脾脏中各T细胞亚群的百分率均降低;而CD4 /CD8 T细胞的比例升高。CTG小鼠的心肌炎症坏死较轻,感染病毒后14d的存活率为85%,显著高于IG的55%(P<0.05)。血清IFN-γ的水平及脾脏中CD3 、CD8 T细胞的百分率显著高于IG组。CTG小鼠脾脏中各T细胞亚群的百分率及CD4 /CD8 T细胞的比例与CG组无显著差异。结论CSAE可诱导VMC小鼠IFN-γ产生并调节细胞免疫功能,对VMC有一定的治疗作用。     

Change in perforin-positive peripheral blood lymphocyte (PBL) subpopulations following exercise

Perforin, one of the cytotoxic proteins of the immune system, plays a prominent role in protection against viral and bacterial infections. We investigated its expression in PBL and their CD3+, CD4+, CD8+ and CD16+ and/or CD56+ subpopulations in endurance athletes before and after a triathlon. Lymphocyte subpopulations were analysed by flow cytometry following separation of peripheral blood mononuclear cells and staining with antibodies against specific membrane antigens and intracellular perforin. The number of total lymphocytes decreased from 2.1 x 10(3)/microl before the triathlon to 1.0 x 10(3)/microl 1 h after the triathlon (P < 0.01). Interestingly, there was already a significant spontaneous decline in the percentage of CD3+/perforin+, and in CD8+/perforin+ cells, in the week proceeding the triathlon, when subjects were instructed to refrain from strenuous exercise training. The percentage of CD3+/perforin+, CD8+/perforin+ and CD16+ and/or CD56+/perforin+ cells in each lymphocyte subpopulation decreased 1 h after exercise even further from 14.3% to 5.8% (P < 0.05), 18.5% to 6.5% (P < 0.05) and 77.3% to 67.3%, respectively. However, at 18 h and 48 h after exercise the percentage of perforin-expressing CD3+, CD8+ and CD16+/56+ cells increased again towards baseline levels. Compared with normal controls, baseline perforin co-expression in CD3+ and CD8+ lymphocytes was significantly higher in trained athletes. From our data we conclude that trained athletes have an increased percentage of perforin+ PBL and that following exercise the percentage of perforin+ and therefore potentially cytotoxic lymphocytes transiently decreases in peripheral blood.     

Expansion of a T lymphocyte subpopulation (CD3+,4-,8-) after immunodepression associated with disseminated histoplasmosis

A major subpopulation of T lymphocytes bearing a high density of CD3 (T3/Leu 4) with no detectable CD4 (T4/Leu 3a) or CD8 (T8/Leu 2a) was found in a patient with cardiomyopathy. Previously the patient had developed disseminated histoplasmosis which had been associated with a profound anergic state. The proportion of CD3+ lymphocytes that bore the phenotype CD3+,4-,8- has been increasing in the absence of reactivation of the histoplasmosis. The CD3+,4-,8- lymphocytes bound anti-CD2 but did not bind WT31, a monoclonal antibody specific for the alpha beta heterodimer of the T cell antigen receptor.     

Genetic control of experimental lyme arthritis in the absence of specific immunity

Host genetics play an important role in determining resistance or susceptibility to experimental Lyme arthritis. While specific immunity appears to regulate disease resolution, innate immunity appears to regulate disease severity. Intradermal infection with Borrelia burgdorferi yields severe arthritis in C3H/He (C3H) mice but only minimal arthritis in BALB/c mice. Intradermal infection of immunodeficient C3H SCID mice also results in severe arthritis, but arthritis of only moderate severity in BALB/c SCID mice. In the present study, we examined immunodeficient recombinase-activating gene-knockout (RAG-1(-/-)) (RAG-) mice from resistant C57BL/6 (B6) and DBA/2 (DBA) mouse strains. B. burgdorferi-infected B6 RAG- and DBA RAG- mice had little or no ankle swelling, a low occurrence of inflammatory infiltrates in tibiotarsal joints, and low arthritis severity scores in comparison to RAG+ and RAG- BALB/c or C3H mice. Few differences in spirochete DNA levels in ankles of resistant and susceptible RAG- mice were seen. These data suggest that resistance to arthritis development following B. burgdorferi infection is not necessarily dependent on an acquired immune response and can occur despite the presence of high spirochete burden. Thus, genes expressed outside the specific immune response can be central regulators of experimental arthritis.     

Protective responses against skin-dwelling microfilariae of Onchocerca lienalis in severe combined immunodeficient mice.

Inoculation of severe combined immunodeficient (SCID) mice with microfilariae of Onchocerca lienalis results in a sustained infection of the skin, extending for months beyond the point at which the parasites are eliminated from immunocompetent BALB/c controls. Reconstitution of SCID mice with spleen cells, thymocytes, or CD4+-cell-enriched splenocytes from naive BALB/c donors confers the ability to mount a protective immune response, leading to the rapid elimination of microfilariae. High levels of interleukin-5 and low levels of gamma interferon in the sera of reconstituted SCID mice during the destruction of microfilariae suggest that this protective immune response is directed by Th2 lymphocytes, mirroring that observed in immunocompetent controls. Unexpectedly, abbreviation of primary infections of unreconstituted SCID mice with the drug ivermectin induces resistance to reinfection with microfilariae at a level equivalent to that induced in secondarily infected, immunocompetent controls. In contrast to protection mediated by adoptive reconstitution, resistance induced by ivermectin-abbreviated infection occurs in the absence of T cells and in association with negligible levels of serum interleukin-5 and gamma interferon. This points to the activation of some alternative host defense mechanism that operates after the clearance of therapeutic levels of drug. Such a response could have important implications for the treatment of human onchocerciasis and may go some way in explaining the long-term suppression of microfilariae observed in patients after treatment with ivermectin.     

Immune disorders in women with premature ovarian failure in initial period

PROBLEM: Premature ovarian failure (POF) may be considered as an autoimmune endocrine disease. Autoantibodies and lymphocyte subset changes are associated with premature ovarian failure. Immune cell parameters were studied in relation with anticardiolipin antibodies (ACAB) classes M and G in the initial period of POF. METHODS: Two-color flow cytometry was used to determine lymphocyte subsets and enzyme-linked immunosorbent assay (ELISA) was used to detect ACAB and hormones in the peripheral blood of 68 POF patients, 32 women with normal menopause (NM) and 13 healthy women as a normal control (NC). RESULTS: Patients in the initial period of POF had decreased levels of CD3+, CD19+, CD3+8+, and CD8+57+ lymphocytes and a high percentage of CD5 positive in CD19+ cell population compared to the control; frequencies of IgM ACAB in POF patients were significantly higher than both IgG ACAB and IgM ACAB in NC; correlation between lymphocyte subsets and hormone levels was absent. Women with early NM showed a low number of CD3+, CD3+4+, and CD3+8+ lymphocytes, a high number of CD3 + DR, and elevation of the percentage of CD5 positive in CD19+ lymphocytes compared with the control. The frequencies of both IgM and IgG ACAB were high; the levels of lymphocyte subsets had correlations with progesterone and estradiol concentrations. CONCLUSIONS: An increase of autoantibody producing B cells (CD5+19+) and a low number of effector suppressor/cytotoxic lymphocytes (CD8+57+) with active production of anticardiolipin autoantibodies class M were found. This suggested a primary autoimmune process in the initial period of POF. Autoimmune defeat of the ovary could be the primary cause of POF, whereas in NM autoimmunity is a result of hormone dysfunction.     

Short-term administration of 17-beta estradiol to outbred male CD-1 mice induces changes in the immune system, but not in reproductive organs

The magnitude of an immune response to many foreign and/or self-antigens is known to be gender-dependent and influenced by sex hormones. While the immune consequences of long-term exposure (3 to 5 months) to natural 17-beta estradiol in an inbred mouse model (e.g., C57BL/6, Balb/c) are relatively well-documented, the immunological effects of shorter-term 17-beta estradiol exposure in an outbred mouse model (CD-1) have not been thoroughly evaluated. The male outbred-CD-1 mouse is considered to be less 17-beta estradiol-responsive (in terms of reproductive changes) compared to the inbred mouse. In the present study, CD-1 male mice were dosed with vehicle, or 17-beta estradiol at 2 or 4 micrg/100 g body weight on alternate days over a 7-day period. The immune changes in the developmental organ (thymus) and mature lymphoid organ (spleen) were determined. Thymic organ weight/body weight ratio and thymocyte cellularity decreased with increasing dose of 17-beta estradiol, reaching significance at the 4 microg dose. Although 17-beta estradiol decreased thymocyte numbers, no differences were noted in the relative percentages of major thymocyte subsets (CD4+CD8-, CD4-CD8+, CD4+CD8+, CD4- CD8-) and no evidence of enhanced apoptosis was found. In contrast to the diminished thymocyte numbers, 17-beta estradiol increased splenic lymphocyte cellularity, especially in mice given 4 microg 17-beta estradiol dose. The functionality of splenocytes from mice exposed to 17-beta estradiol was also altered. Supernatants from Con-A activated splenocytes from 17-beta estradiol-treated mice had increased IFN-gamma and decreased IL-4 levels (p < 0.05 at the 4 microg dose). This increase in IFN-gamma in 17-beta estradiol-treated mice was not due to an increase in the relative percentages of T cells, since they were comparable to relative percentages of T cells from oil-treated control mice. In addition, supernatants from cultured splenocytes (both Con A-activated and unstimulated) also had significantly higher levels of nitric oxide activity, especially at the 4 microg 17-beta estradiol dose. These results indicate that short-term 17-beta estradiol treatment in outbred mice, at relatively modest doses (2-4 microg/100 g body weight), altered both thymocytes and splenocytes. These 17-beta estradiol-induced immune changes are compelling, since in these mice, post-17-beta estradiol exposure did not demonstrate robust changes in the male reproductive system (testicular and seminal vesical weights to body weight ratios).     

In vivo depletion of BoT4 (CD4) and of non-T4/T8 lymphocyte subsets in cattle with monoclonal antibodies

The effect on certain immune responses of depleting two distinct lymphocyte subpopulations in vivo by inoculating calves with monoclonal antibodies (mAb) was examined. An mAb directed against the BoT4 antigen (the bovine homologue of CD4) effectively removed the BoT4+ lymphocytes from peripheral blood mononuclear cells (PBM). Compared to controls, treated calves showed a reduced antibody response to human O red blood cells and to ovalbumin. PBM prepared from BoT4-depleted animals also had a significantly reduced ability to respond in vitro to the mitogens phytohemagglutinin, concanavalin A and pokeweed mitogen. An mAb directed against a second numerically large bovine lymphocyte subpopulation i.e. BoT2-, BoT4-, BoT8- (CD2-, CD4-, CD8-), that may be homologous to the CD4-, CD8- cells in man and rodents that synthesize the gamma/delta+ T cell receptor, was also used for in vivo depletion. Compared to controls, calves depleted of this subpopulation showed an enhanced antibody response. The proliferative response of PBM to pokeweed mitogen was also significantly increased but responses to concanavalin A and phytohemagglutinin remained unchanged. The results suggest this lymphocyte subpopulation has a nonspecific suppressor activity acting on B cell responses either directly or through an effect on T helper cells. The non-T4/T8 cells are found extensively in the epithelium and lamina propria of the mucosa of the alimentary tract but not in T cell areas of the lymph nodes, tonsil and spleen. These non-T4/T8 cells may thus be, or contain, an intraepithelial lymphocyte population with a suppressor function.     

Gamma interferon-dependent temporary resistance to acute Toxoplasma gondii infection independent of CD4+ or CD8+ lymphocytes.

It is well established that resistance to acute primary Toxoplasma gondii infection is mediated by a gamma interferon (IFN-gamma)-dependent mechanism. The present in vivo experiments were undertaken to investigate the cellular basis for this resistance. We show here that immunocompetent T. gondii-infected C57BL/6 (B6) mice treated with anti-IFN-gamma or with anti-Thy-1 or anti-asialo-GM1 antibodies die sooner than infected mice treated with antibodies that deplete both CD4+ and CD8+ T lymphocytes. Thy-1+ CD4- CD8- cells accumulated in the peritoneal cavities of B6 mice during the early stages of an intraperitoneal infection but did not accumulate in sham-infected control mice, and substantial numbers of Thy-1+ CD4- CD8- cells were recovered from the peritoneal cavities of infected B6 mice treated with antibodies that depleted CD4+ and CD8+ lymphocytes. Depletion of Thy-1+ cells reduced IFN-gamma to undetectable levels, whereas depletion of CD4+ and CD8+ cells did not reduce IFN-gamma levels. Thus T. gondii infection in immunocompetent B6 mice elicits Thy-1+ CD4- CD8- cells which either produce protective IFN-gamma themselves or control its production by other cells. It is likely that the function of these Thy-1+ CD4- CD8- cells is to control T. gondii tachyzoites during the early stages of primary infection before specific CD4(+)- and/or CD8(+)-dependent immunity develops.     

Genetically programmed biases in Th1 and Th2 immune responses modulate atherogenesis

Atherosclerotic lesions contain T lymphocytes, which orchestrate adaptive immunity and regulate many innate immune pathways. This study examined the influence of Th1 and Th2 helper cell subsets on atherogenesis in two ApoE(-/-) mouse strains, C57BL/6 and BALB/c, which display opposite T-cell subset polarizations. ApoE(-/-) BL/6 mice showed predominant Th1-like immune responses on polyclonal stimulation of splenic CD4(+) T cells and had IgG2a antibodies to oxidized low-density lipoprotein (a disease-related antigen) whereas ApoE(-/-) BALB/c mice displayed predominant Th2 responses by CD4(+) T cells and an IgG1 isotype response toward oxidized low-density lipoprotein. ApoE(-/-) BL/6 and BALB/c mice consumed a high-cholesterol diet for 10, 16, and 24 weeks with equivalent cholesterolemic responses. The Th1-slanted BL/6 mice developed significantly more atherosclerosis in the aortic root and abdominal aorta at all time points compared with BALB/c mice, supporting a proatherogenic role for Th1 response. Progression of atherosclerosis was associated with increased levels of interleukin (IL)-6 in mouse serum and CD4(+) T-cell culture supernatants and increased levels of the acute-phase protein, serum amyloid A (SAA). Both IL-6 and SAA levels rose significantly in ApoE(-/-) BL/6 mice compared with BALB/c mice. The circulating cytokine milieu (IL-6) and acute phase reactants such as SAA may reflect alterations in the Th1/Th2 balance. The results presented here illustrate how genetically determined modifiers of both immune and inflammatory responses can modulate atherogenesis independently of lipid levels.     

Clonally expanded CD3+, CD4-, CD8- cells bearing the alpha/beta or the gamma/delta T-cell receptor in patients with the lymphoproliferative disease of granular lymphocytes.

Among 60 retrospectively assessed patients with the lymphoproliferative disease of granular lymphocytes (LDGL), lymphocytes from only 2 patients had the CD3+, CD4-, CD8- phenotype, rarely observed in normal peripheral blood lymphocytes (about 3%). In this paper we report a detailed study of lymphocytes isolated from these two patients. The cells from patients 1 had the CD3+, CD4-, CD8-, WT31-, beta F1-, TCR delta 1+, Ti gamma A-, BB3+, CD7+, CD16-, CD57+ phenotype, while cells from patient 2 had a phenotype even more rarely observed on normal lymphocytes: CD3+, CD4-, CD8-, WT31+, beta F1+, TCR delta 1-, CD7+, CD16-, CD57+. Thus, in only the first case the cells expressed the gamma/delta T-cell receptor (TCR) on the membrane, while the cells from the second case had the alpha/beta TCR. Genetic studies showed that in case 1 the TCR gamma gene was rearranged and the beta chain gene configuration was germline; the TCR mRNA was of normal size for the gamma chain, while that of the beta chain was truncated. Case 2 had the beta and the gamma genes of the TCR rearranged, but only the alpha and beta mRNA were expressed. In agreement with these findings, the delta chain gene of the TCR was rearranged in case 1 and was deleted in case 2. Cytotoxic activity was absent in cells from case 1 and low in case 2; in the latter, the lytic activity could be up-regulated following incubation with IL-2 or an anti-CD3 monoclonal antibody. Our study indicates that CD3+, CD4-, CD8- lymphocytes are rarely expanded in patients with LDGL. The detection of a lymphoproliferative disease of a CD3+, CD4-, CD8-, alpha/beta + cell may contribute to a better characterization of this novel lymphocytic subpopulation.