Membrane and functional characterization of lymphoid and macrophage populations of Peyer's patches from adult and aged mice.

Properties of macrophages isolated from Peyer's patches were compared with properties of peritoneal macrophages. We found a very low expression of all types of Fc receptors as well as a low expression of Ia antigens on Peyer's patch macrophages. No substantial changes in the levels of FcR and Ia antigen expression were found during the process of ageing. The investigation of phagocytic activity showed the activated state of Peyer's patch macrophages. Comparing the surface markers of lymphocytes obtained from Peyer's patches of mice of different ages, we found no differences in the numbers of sIg+, Thy-+ or L3T4+ lymphocytes. The numbers of FcR+ and Lyt 2.2+ lymphocytes decreased markedly with age.     

IgE receptors on human lymphocytes. II. Detection of cells bearing IgE receptors in unstimulated mononuclear cells by means of a monoclonal antibody

A monoclonal antibody (mAb) specific for lymphocyte IgE receptors (ER) was employed in a rosette assay for the detection of cells bearing IgE receptors (Fc epsilon R). The specificity of the assay was documented by inhibition studies with soluble immunoglobulins (Ig) and anti-Ig antibodies. Moreover, similar results were obtained by employing the F(ab')2 fragment of mAbER instead of intact molecule. Circulating mononuclear cells isolated from normal or allergic adults and from umbilical cord blood contained approximately 8% of Fc epsilon R-bearing cells with values ranging from 0.3 to 17%. Tonsillar lymphocytes contained about 30% of Fc epsilon R+ cells. After the removal of adherent cells, there was a small but significant reduction of the proportion of Fc epsilon R+ cells. When mononuclear cells were separated into T and B cell fractions by two-cycle rosetting with 2-aminoethylisothiouronium bromide hydrobromide-treated sheep red blood cells, most of the Fc epsilon R+ cells were in the B cell fraction; however, a small proportion of Fc epsilon R+ was also found in the enriched T cells and double-labeling experiments confirmed that these cells were indeed T lymphocytes. Fc epsilon R+ cells were purified by rosetting with mAbER-coated erythrocytes and their phenotype was compared to that of Fc epsilon R- cells; Fc epsilon R+ cells contained about 90% of B cells (B1+) together with a small proportion of OKT3+, Leu 7+ and Mo2+ cells. The bulk of T cells, macrophages and natural killer (NK) cells was found in the Fc epsilon R- cells which contained fewer B cells than the fraction of Fc epsilon R+ cells. These data thus indicated that the great majority of Fc epsilon R-bearing cells are B cells but that a small proportion of NK cells, macrophages and T lymphocytes also express Fc epsilon R. Upon incubation at 37 degrees C, B cells lost their Fc epsilon R and this phenomenon was selectively inhibited by IgE; however, purified T cells seemed to express more Fc epsilon R after overnight incubation at 37 degrees C and this was not influenced by IgE. It is finally shown that the expression of Fc epsilon R is cyclic and that Fc epsilon R-bearing B cells do not represent a functionally distinct subpopulation of B lymphocytes.     

The expression of IgE Fc receptors on lymphocytes of allergic patients

Peripheral blood lymphocytes from nonatopic subjects and atopic patients were analyzed for cells expressing Fc receptors for IgE (Fc epsilon R). Nonatopic humans and atopic patients in remission had approximately 1 percent of Fc epsilon R+ peripheral blood lymphocytes. Usually greater than 99 percent of these cells were mIgM+/mIgD+ B cells. However, in approximately 10 percent of nonatopic and atopic subjects a transient increase of Fc epsilon R+ lymphocytes to 3-6 percent was observed in the absence of any disease manifestations and measurable changes in the serum IgE level. At times of increased numbers of peripheral blood Fc epsilon R+ lymphocytes, up to 1 percent Fc epsilon R+ positive cells were detected in isolated T cell preparations. The Fc epsilon R+ T cells reacted with the monoclonal antibody Lyt 3 to the sheep erythrocyte receptor of human T cells but not the anti-T cell antibody OKT3, and fractions also with the monoclonal antibodies OKT8 (cytotoxic and suppressor T cells) and OKM1, which binds to an antigen present on monocytes and a subpopulation of T cells and large granular lymphocytes. No OKT4+ (helper T cells) Fc epsilon R+ cells were detected. The reactivity with monoclonal antibodies to T cell subsets of the Fc epsilon R+ T cells paralleled the reactivity of the IgG Fc receptor positive T cells. In contrast to patients with allergic rhinitis and asthma, patients with severe atopic dermatitis or the Hyper IgE Syndrome always had significantly elevated percentage of Fc epsilon R+ lymphocytes (4-10 percent), which were almost entirely B cells since less than 0.1 percent Fc epsilon R+ T cells were detected in these patients. Atopic dermatitis patients receiving systemic corticosteroid treatment had only 0.2 percent Fc epsilon R+ lymphocytes which was significantly less than the 1 percent of the nonatopic control donors. Attempts to define the function of Fc epsilon R on human B and T lymphocytes have been unsuccessful thus far; however, the increase of Fc epsilon R+ cells associated with atopic disease in man and parasitic infections in rats and mice suggest that Fc epsilon R+ lymphocyte may be involved in the IgE isotype regulation.     

Regulation of in vivo expression of Fc receptors for IgE (Fc epsilon R) on murine lymphocytes. I. Detection of Fc epsilon R+ lymphocytes by flow cytometry

Homologous monomeric IgE was employed in a flow cytometric assay for the detection of IgE Fc receptors (Fc epsilon R) on mouse lymphocytes. The expression of Fc epsilon R in normal BALB/c mice was detected on splenic and circulating lymphocytes, but not on bone marrow cells. The Fc epsilon R expression was observed in B cells with B220, surface IgM, and IgD, but not in T cells. Infection of mice with Nippostrongylus brasiliensis resulted in a marked increase in the expression of Fc epsilon R on splenic B cells. T cells, however, did not express Fc epsilon R even after N. brasiliensis infection. On the other hand, the Fc epsilon R expression on normal B cells decreased after a simple incubation at 37 degrees C for 24 h, while in the presence of IgE this decrease was inhibited. In contrast, B cells stimulated with interleukin 4 display Fc epsilon R with high densities. Interestingly, IgE enhanced the Fc epsilon R expression induced by interleukin 4, suggesting that both interleukin 4 and IgE may be responsible for an increase in the expression of Fc epsilon R on B cells of N. brasiliensis infected mice.     

Short-term Administration of Ethanol in Mice Deviates Antigen Presentation Activity Towards B Cells

Alcohol has a variety of short- and long-term effects on cell-mediated and humoral immune response. Herein, we have characterized the impact of high-dose EtOH administration on phenotypic and functional features of murine APC subsets, including dendritic cell (DC), macrophages and B cells. Impaired cytokine synthesis and Leishmania -phagocytosis was observed in peritoneal macrophages following EtOH administration . Moreover, EtOH exposure led to decreased levels of splenic myeloid DC and increased percentage of macrophages with no changes in splenic lymphoid DC and B cells. Adverse effects of short-term EtOH administration also resulted in impaired OVA-endocytosis by DC and macrophages. In contrast, EtOH consumption upregulates OVA-internalization by B cells. These changes on APC hierarchy may play a role shifting the fate of the immune response after EtOH ingestion. In addition to an overall downregulation of Toll-like receptor-TLR-4 expression by splenic APC, a downregulation of TLR-2 expression in macrophages was observed. Moreover, EtOH exposure altered the expression of co-signalling molecules on splenic APC, downregulating CD40 on macrophages and upregulating CD80 on B cells, with no impact on DC subsets. The net result of changes in TLR-mediated and co-stimulatory signals may determine the altered immunological status induced by acute consumption of alcohol. A direct impact of high-dose EtOH administration in the activation status of splenic CD4⁺ T cells was observed. Together, our results demonstrated that short-term high-dose EtOH administration has differential impact on APC populations, downregulating splenic macrophages and DC activity but up-regulating B lymphocyte function as APC, and ultimately yielding a micro-environment that led to increased activation of CD4⁺ T cells.     

Immunomodulation of polypeptides fromChlamys farreri in vitro

Polypeptides fromChlamys Farreri(PCF) ,a wa-ter soluble octopeptide ,wasisolatedfromChlamysFarreribyenzyme engineering.The previous stud-iesin our laboratory showed that PCF was capableof protectingimmunocytesfromthe damages of Ul-traviolet or60Co,andthat PCFcouldresist the de-pression of lymphoproliferation caused by E2[1 ,2] .Based onthe earlier studies ,wefurtherinves-tigatedthe effects of PCF on immunityin vitrosoasto provide experimental basisforthe exploitationof PCF.MATERIAL…     

Infection of mice with Mycobacterium avium primes CD8+ lymphocytes for apoptosis upon exposure to macrophages

Mycobacterial infection is associated with granuloma formation in which the presence of apoptosis has been recognized. The role of CD4+ T and CD8+ T cells in host protection against mycobacterial infections has been demonstrated. Previous studies, however, have shown that CD8+ T cells have a limited role in host defense against Mycobacterium avium infection, and we hypothesize that M. avium infection could lead to T cell apoptosis. To investigate this hypothesis, C57BL/6 mice were infected with M. avium strain 101, and the rate of apoptosis of splenic lymphocytes cultured ex vivo with peritoneal macrophages was determined and compared with that of controls. When exposed to infected macrophages ex vivo, splenic lymphocytes from M. avium-infected mice underwent apoptosis, as determined by the TUNEL assay. This increased T cell apoptosis above the control level was observed after 3 weeks but not after only 1 week of infection in mice. No splenic T cell apoptosis was observed when lymphocytes from Mycobacterium smegmatis-infected mice were cultured in the presence of M. smegmatis-infected peritoneal macrophages. Likewise, macrophages infected in vitro with heat-killed M. avium did not trigger T cell apoptosis. Culture of macrophages in different chamber from lymphocytes, separated by a transwell membrane, was not associated with increase of apoptosis compared with uninfected control, suggesting a requirement for direct cell-cell interactions to trigger lymphocyte apoptosis. Using a double staining TUNEL followed by anti-mouse CD4 or anti-mouse CD8 monoclonal antibodies, it was observed that only CD8+ T cells but not CD4+ T cells underwent apoptosis at 3 weeks of infection. In conclusion, M. avium infection in C57/BL6 mice for 3 weeks renders CD8+ T cells prone to apoptosis when exposed ex vivo to macrophages infected with M. avium.     

Spontaneous interaction in vitro between lymphocytes and syngeneic peritoneal macrophages of mice.

Ficoll-purified lymphocytes (peritoneal, splenic, or thymic) and macrophages (peritoneal) from Toxoplasma-immune and normal female NMRI mice were used. Suspensions of washed cells were made in medium 199 containing 20% heat-inactivated normal calf serum. Sixty minutes after the adherence of 10(5) macrophages to cover slips in Leighton tubes, lymphocytes were added in various concentrations. The mixed cellular population was then incubated at 37 C. Eighteen hours later, most of the lymphocytes were firmly attached to macrophages to form rosettes. This cellular interaction, which was temperature, cell ratio, and time dependent, occurred in the absence of any particular antigenic stimulation. Morever, the reaction was cytotoxic only for adhered lymphocytes as judged by staining with 0.2% trypan blue. Splenic and thymic lymphocytes were bound in significantly greater number than peritoneal lymphocytes. Incubation of macrophages for more than 48 h at 37 C before the addition of fresh lymphocytes markedly reduced rosette formation. Treatment of macrophages and lymphocytes with mouse anti-immunoglobulin did not affect the reaction. The labeling of lymphocytes with fluorescent anti-mouse sera and the use of nude NMRI mice showed that both B and T cells can form spontaneous rosettes with syngeneic peritoneal macrophages.     

Macrophages but not B cells from aged mice are defective in stimulating autoreactive T cells in vitro

In the present study the effect of aging on the capacity of Ia+ cells to stimulate autoreactive T cells in the syngeneic mixed lymphocyte reaction (SMLR) was investigated. Using young CD4+ T cells as responders, it was observed that unseparated whole spleen cells from aged mice had normal stimulatory activity comparable to that of young spleen cells. Interestingly, however, when purified splenic adherent cells (SAC) enriched for macrophages or splenic B cells were used as stimulators, aged SAC but not aged B cells were found to be defective in stimulating autoreactive T cells. This defect in aged SAC was not due to decreased expression of Ia antigens since the percentage of Ia+ SAC and density of Ia antigen expression was similar in both young and old mice. Also, the B cells from aged mice expressed normal levels of Ia antigens. Aged SAC, when mixed with young SAC could also actively suppress the normal SMLR. However, this suppression was not due to increased prostaglandin production but was found to be associated with interleukin-1 (IL-1) regulation, inasmuch as addition of exogenous IL-1 could completely reconstitute the defective stimulatory activity of aged SAC and also abolished the suppressor activity of the SAC. Aged mice also demonstrated an intrinsic defect in the CD4+ T cells responding in the SMLR. Together, our studies on the SMLR demonstrate an age-related defect in responder autoreactive T cells and in stimulator splenic macrophages but not in the stimulatory activity of B cells.     

Expression of the CMRF-35 antigen, a new member of the immunoglobulin gene superfamily, is differentially regulated on leucocytes.

A new monoclonal antibody, CMRF-35, has been generated that recognized a 224 amino acid cell surface protein which is a novel member of the immunoglobulin gene superfamily. The antibody, raised against large granular lymphocytes (LGL), stains LGL, monocytes, macrophages and granulocytes but not platelets or erythrocytes. In addition, a subset of peripheral blood T lymphocytes (26.6 +/- 13.4% CD5+ cells) and B lymphocytes (13.7 +/- 6.8% CD20+ cells) stained with CMRF-35 but tonsil T and B cells were essentially negative. Expression of the CMRF-35 antigen (Ag) on different leucocyte populations was markedly influenced by stimulation of the cells with mitogens and cytokines. Activation of peripheral blood T cells with phytohaemagglutinin (PHA), or phorbol myristate acetate (PMA) and calcium ionophore (CaI) led to a decrease in the proportion of CMRF-35+ T lymphocytes. In contrast, PHA activation of tonsil T lymphocytes resulted in an increase in CMRF-35 Ag expression (47.1 +/- 1.5% CD5 cells at 6 days). An increase in CMRF-35 Ag was also seen on phorbol ester and CaI-activated tonsil B cells. No change in CMRF-35 expression on natural killer (NK) cells occurred following activation with interleukin-2 (IL-2) but the CMRF-35 Ag was down-regulated following Fc receptor stimulation. A moderate increase in CMRF-35 expression occurred during monocyte-macrophage differentiation and the expression of the Ag on monocytes was differentially regulated by interferon-gamma (IFN-gamma). This regulation of the CMRF-35 Ag on the leucocyte surface suggests that the molecule has an important function common to diverse leucocyte types.     

Splenic B cells function as immunogenic antigen-presenting cells for the induction of effector T cells

Previous studies performed in our laboratory have revealed that an ordered, sequential, tricellular interaction is obligatory for the antigen-driven induction of a specific effector memory T cell. Thus, it was found that antigen-pulsed peritoneal macrophages signal, in spleen cells, the generation of antigen-specific initiator lymphocytes. These lymphocytes, following injection to syngeneic recipients, recruit, in the draining lymph nodes, "virgin" antigen-reactive T lymphocytes. Although the nature of the first and last cell in the interacting sequence was well characterized, the identity of the intermediary initiator splenic cell was obscure. Studies were carried out to characterize the nature of the splenic initiator cells. It was found that spleen cells from nu/nu, adult thymectomized and neonatal thymectomized, or spleen cells from normal donors which had been subjected to cytolysis using anti-Thy-1.2 antibodies in the presence of complement, did generate, following interaction with keyhole limpet hemocyanin (KLH)-fed macrophages, specific initiator cells. Carrageenan impairment of spleen macrophages did not affect the generation of initiator cells, nor did the depletion of dendritic cells from the spleen. On the other hand highly enriched B cell, but not highly enriched T cell populations, when seeded on KLH-pulsed macrophages, generated antigen-specific initiators, which, in vivo, recruited antigen-reactive T cells. It thus appeared that B lymphocytes can function as intermediary obligatory antigen-presenting cells and actively transfer immunogenic signals from peritoneal antigen-presenting cells to T lymphocytes. These findings may therefore suggest that antigen-specific B cells do not function solely as antibody-producing cells, but, once activated by macrophages, may control the induction and differentiation of some antigen-reactive T cell subsets. Thus, one can view the B cell as an important regulatory cell of both cellular and humoral immune functions. The significance of this observation with regard to Ir gene control at the level of B lymphocytes is discussed.     

Etiology of the liver granulomatous response in Schistosoma mansoni-infected athymic nude mice.

The effect of schistosome infection on the presence and maturation of splenic T lymphocytes in C3H/HeN nu/nu and nu/+ mice was examined. Spleens of uninfected nu/nu mice contained very low numbers (u to 2%) of T lymphocytes. This percentage did not increase throughout the 10 weeks of the infection. Spleens of uninfected nu/+ littermates contained 28.8% T cells, which decreased to 15.0% by week 10 of the infection. Similarly, whereas spleen cells of normal or infected nu/nu mice were nonresponsive to concanavalin A, the initial high response of nu/+ mice gradually diminished. Both nu/nu and nu/+ spleen cells responded well to lipopolysaccharide initially, but by 10 weeks their responsiveness declined. Sera of five infected nu/nu mice contained no antibodies to egg antigens, and one had a low titer (log2 5.0). In contrast, the mean titer of sera from six nu/+ mice was log2 10.7 Nu/+ mice had typical florid lesions, but nu/nu mice mounted sparse granulomatous reactions around eggs in the liver without evidence for hepatocellular damage. Dispersed liver granulomas of nu/nu mice contained 1.2% T and 20.3% B lymphocytes. Lesions of nu/+ mice contained 12.9% T and 18.4% B cells. Eighty percent of the macrophages from nu/nu and nu/+ granulomas displayed high density/avidity Fc receptors. Production of migration inhibition factor-active lymphokine by liver granulomas and spleens of schistosome-infected nu/nu mice is suggestive of the immune role of B cells in the granulomatous inflammation.     

CCK-8上调小鼠腹腔巨噬细胞B7.1和B7.2表达并增强其协同刺激活性

目的： 探讨八肽胆囊收缩素（CCK-8）对静息巨噬细胞B7.1和B7.2表达及其协同刺激功能的影响。方法：用CCK-8（10-12-10-6 mol/L）孵育小鼠腹腔巨噬细胞一定时间，采用流式细胞术分析细胞表面B7.1和B7.2含量的变化。用免疫磁珠从小鼠脾细胞分离CD4+T细胞，按4∶〖KG-*2〗1数量比与腹腔巨噬细胞（预先用CCK-8和/或抗B7.1抗体、抗B7.2抗体、CCK1R拮抗剂CR1409、CCK2R拮抗剂CR2945孵育24 h）共同体外培养，同时加入ConA 5 mg/L，采用［3H］掺入法测定CD4+T细胞增殖反映巨噬细胞的协同刺激活性。结果：CCK-8可上调静息巨噬细胞B7.1及B7.2的表达，并增强巨噬细胞的协同刺激活性。CCK-8的作用呈剂量依赖性，最大效应剂量是在10-9-10-7 mol/L之间。抗B7.2抗体可减轻CCK-8增强巨噬细胞协同刺激活性的作用，CR1409及CR2945均能逆转CCK-8的上述作用，且CR1409的作用较CR2945更明显。结论：CCK-8通过上调巨噬细胞B7.2表达而增强其协同刺激活性，该作用由CCK1R及CCK2R介导，其中CCK1R起主要介导作用。     

The expression of Fc and complement receptors in young, adult and aged mice.

Age-dependent changes in the expression of Fc receptors (FcR) for different isotypes of immunoglobulins and receptors for C3b, C5b and C3bi fragments of complement on the membranes of peritoneal macrophages were studied with mice of different ages. An age-related increase in expression of Fc receptors for IgM, IgE, IgA, IgG2b and IgG3, and a decrease in the expression of Fc receptors for IgG1 was observed. The expression of FcR on macrophages of donors of different ages corresponded with Fc-receptor mediated phagocytosis. The highest number of C3b-binding macrophages was found in aged mice, in contrast to low numbers of C3bi-binding macrophages at this age. The percentage of C5b-binding macrophages was lowest in adult animals. We also observed effective inhibition of binding of the C3b component of complement by preincubation of macrophages with aggregated IgG and vice versa. These observations suggest that fluctuation in expression of Fc but not C receptors may be important to the generalized changes that occur in macrophage function during development and ageing.     

Co-expression of different types of Fc receptors on murine peritoneal macrophages

Simultaneous expression of particular immunoglobulin Fc receptors (FcR) was studied on the plasma membranes of murine peritoneal macrophages. This was facilitated by the use of sheep red blood cells (SRBC) and/or synthetic microspheres coated with monoclonal antibodies of different isotypes. It was concluded that a majority of macrophages bear more than one type of FcR; macrophages bearing at least three types of FcR were present in the peritoneal cavity; macrophages bearing Fc mu R did not bind IgE, IgA or IgG; all macrophages bearing Fc alpha R also expressed Fc gamma 2bR, Fc gamma 3R and Fc epsilon R; all macrophages bearing Fc epsilon R also expressed Fc gamma 2bR and Fc alpha R. Except for Fc alpha R, essentially equivalent numbers of FcR-bearing macrophages were detected when antibody-coated SRBC or polymeric microspheres were used. Simultaneous applications of these reagents permitted the most detailed and direct investigations yet performed of multiple FcR expression on individual cells.     

Expression of class II major histocompatibility complex antigens on adult T cells in Xenopus is metamorphosis-dependent

Class II major histocompatibility complex (MHC) antigens are expressed predominantly on B lymphocytes and macrophages of tadpoles of the South African clawed frog, Xenopus laevis, as is the pattern in lymphocyte populations of most mammals. However, unlike most mammals, young postmetamorphic frogs show expression of class II MHC antigens on a high proportion of thymocytes and most peripheral T and B lymphocytes. Using the J-strain of Xenopus and the anticlass II monoclonal antibody, 14A2, we have studied, by indirect immunofluorescence, whether inhibition of metamorphosis would alter the pattern of expression of class II antigens during ontogeny. In control animals, class II antigens were virtually absent from thymic lymphocytes and peripheral T cells of normal untreated larvae, but could be found in increasing numbers in both populations after metamorphosis (10-12 weeks of age). In contrast, larvae, whose metamorphosis was inhibited by treatment with sodium perchlorate, had relatively few class II+ thymic lymphocytes throughout the 6-month period of study, and the proportion of class II+ splenic lymphocytes was approximately equal to that of IgM+ B lymphocytes. Thus, perchlorate-treated animals retained the larval pattern of class II expression, suggesting that emergence of class II+ T cells is dependent on metamorphosis.     

Decrease in helper (T4+) lymphocytes following cimetidine treatment for duodenal ulcer.

We studied the possible in vivo influence of cimetidine on peripheral blood lymphocyte (PBL) subpopulations defined with monoclonal antibodies (MoAb) in eight haematologically normal patients with uncomplicated duodenal ulcers before cimetidine treatment, 1 week after the start, and finally 1 week following cessation of therapy. After cimetidine had been given for 3-5 weeks there was a significant decrease, compared with pretreatment numbers, in the proportion of T3+ cells (64.6 +/- 8.1 (mean +/- s.d.) v 51.0 +/- 7.8%) and in T4+ cells (47.3 +/- 4.3 v 30.8 +/- 4.7%). The number of T8+ cells was not affected (20.3 +/- 4.3 v 20.1 +/- 6.7%). These changes resulted in a significant reduction in the T4/T8 ratio (2.46 +/- 0.8 v 1.67 +/- 0.6). The total numbers of lymphocytes and monocytes as well as the percentage of B1+ lymphocytes did not change significantly. The observed decrease in T4/T8 ratio after cimetidine treatment is explained by a reduction in the number of T4+ cells and the appearance of a new subpopulation of T3-, T4-, T8-, B1-lymphocytes. The underlying mechanism, however, is not clear. Cimetidine does not seem to have a direct receptor-modulating effect, since in vitro exposure of normal lymphocytes to the drug did not change the proportions of the T cell subsets.     

The expression of B cell surface receptors. III. The murine low-affinity IgE Fc receptor is not expressed on Ly 1 or 'Ly 1-like' B cells.

The distribution of IgE FcR (Fc epsilon R)-positive and -negative B cells was examined in normal adult mice. Using three-color flow cytometry, the expression of the Fc epsilon R was analyzed on various B-cell subsets present in the peritoneum and spleen. The results demonstrate that in the peritoneal cavity, the Fc epsilon R is not expressed on the large majority of Ly 1+ B cells and Ly 1-, Mac 1+ sister B cells. The receptor is present, however, on the small number of conventional B cells residing in the peritoneum. Although interleukin 4 (IL-4) can increase the levels of the Fc epsilon R on conventional B cells, incubation of Ly 1 and sister B cells with IL-4 did not result in the expression of the Fc epsilon R. When examining B cells present in the spleen, a small subset of B cells was consistently found to be Fc epsilon R-. These Fc epsilon R- cells were IgM-bright, IgD-dull and largely Ly 1- and Mac 1-negative. Staining of splenic tissue sections revealed that the Fc epsilon R- B cells were primarily localized to the marginal zones, whereas the Fc epsilon R+ B cells were found in the follicles. Taken together, the results indicate that the Fc epsilon R may be a useful marker in delineating the various B-cell subsets. In the peritoneum, the Fc epsilon R appears to discriminate conventional B cells from those of the Ly 1/sister lineage, and in the spleen it is likely to distinguish resting follicular B cells from Ly 1/sister and marginal zone B cells.     

Induction of C3b-mediated phagocytosis in macrophages by distinct populations of lipopolysaccharide-stimulated lymphocytes.

Unelicited resident peritoneal macrophages do not significantly ingest erythrocytes coated with C3b. However, these resident macrophages can be induced to ingest via the C3b receptor when cocultured with peritoneal or splenic nonadherent cells obtained from mice previously injected with lipopolysaccharide. In this study, the extent of ingestion induced in resident macrophages was dependent on the number of stimulated nonadherent cells cocultured with the macrophages as well as on the amount of lipopolysaccharide injected in the mice from which the nonadherent cells were obtained. The ability of the stimulated nonadherent cells to convert resident macrophages to a state of C3b receptor-mediated ingestion was not abrogated by the inclusion of polymyxin B in the cocultivation medium. To further characterize these nonadherent cells, different lipopolysaccharide-stimulated cells were obtained by either nylon-wool filtration, depletion of C3b receptor-bearing cells, or depletion of Thy 1.2-positive cells. None of these populations by themselves were capable of inducing resident macrophages to ingest via the C3b receptor, whereas unfractionated cells were. However, coculture of resident macrophages with recombinations of splenic nylon-wool effluent (T cell-enriched) or bound (B cell-enriched) nonadherent cells from lipopolysaccharide-injected mice reconstituted the ability to induce ingestion via the C3b receptor. Taken together, these results suggest that one means by which lipopolysaccharide can induce C3b receptor-mediated ingestion by macrophages is through the cooperative effects of stimulated T and B lymphocytes.     

Compartmentalization of T cell responses following respiratory infection with Bordetella pertussis: hyporesponsiveness of lung T cells is associated with modulated expression of the co-stimulatory molecule CD28

We have used a murine respiratory challenge model to examine the local T cell responses in the lung during infection with Bordetella pertussis. T cells from lung parenchyma and airways of naive and infected mice were refractory to both antigen and mitogen stimulation in the presence of lung macrophages. Furthermore irradiated mononuclear cells from the lungs suppressed antigen and mitogen-induced proliferation, but not IFN-γ production, by splenic T cells. Removal of macrophages and stimulation of purified lung T cells in the presence of irradiated splenic antigen-presenting cells fully restored the response to mitogen. However, T cells purified from the lung during the acute phase of infection with B. pertussisfailed to proliferate or produce detectable levels of IL-2, IL-4, IL-5 or IFN-γ in response to purified bacterial antigens. In contrast, splenic T cells from these animals produced high levels of IL- 2 and IFN-γ and proliferated strongly to a range of bacterial components. Phenotypic analy sis of bronchoalveolar lavage cells during the course of infection revealed transient infiltra tion of neutrophils, followed by macrophages, CD4+ T cells and smaller numbers of CD8+ T cells and γ δ+ T cells. Cell surface expression of B7 on infiltrating macrophages and CTLA-4 on T cells did not change significantly during infection. However, expression of the CD28 co- stimulatory molecule was profoundly reduced on lung T cells during the acute phase of infection. In contrast, lung T cells from mice primed by B. pertussisinfection or vaccination were resistant to CD28 down-regulation. These results suggest compartmentalization of T cell responses between the lung and the periphery during B. pertussisinfection and that B. pertussismay have immunomodulatory properties on local T cell populations in the lungs of naive mice.