The regulatory role of macrophages in antigenic stimulation. Part Two: symbiotic relationship between lymphocytes and macrophages

Tissue macrophage response in human papillomavirus infection and cervical intraepithelial neoplasia

Tissue macrophages in the uterine cervix were studied immunocytochemically with monoclonal antibody (MoAb) 3.9 which reacts with the majority of macrophages, and E11 which is specific for the C3b receptor, CR1. Samples from five normal women, six with human papillomavirus (HPV) infection and 10 with cervical intraepithelial neoplasia (CIN) were tested. A small population of MoAb 3.9 positive and only occasional MoAb E11 positive macrophages were found in the normal cervix. In HPV infection and CIN there was a significant infiltration of MoAb 3.9 positive and MoAb E11 positive macrophages in both the epithelium and the stroma. The pattern of infiltration in these groups of women suggests that these macrophages were most likely to be functioning as the first line of defence against the spread of the virus infection, either through a direct anti-virus mechanism or non-specific phagocytosis.

Inhibition by anti-HLA class II monoclonal antibodies of monocyte-dependent T cell proliferation induced by monoclonal antibody OKT3

The inhibitory effect of monoclonal antibodies (mAb) to monomorphic (locus-restricted and locus-shared) and polymorphic determinants of HLA class II antigens on the monocyte-dependent proliferation of T cells stimulated with mAb OKT3 has been studied. The effect appears to be specific, dose dependent, is not mediated by the Fc portion of mAb and reflects their interaction with the corresponding determinants. The anti-HLA class II mAb do not have to be present in the culture throughout the incubation period, but are essential in early phases of mAb OKT3 T cell activation. Both monocytes and T cells are the targets of the inhibition exerted by the anti-HLA class II mAb. Their inhibitory effect involves several steps in the sequence of events which leads to T cell proliferation, including interleukin (IL) 1 and 2 secretion, and IL2 receptor expression.

Characterization of a product of histoincompatible spleen cells restoring class I-inhibited mixed-lymphocyte culture reactions

Conditions leading to the formation of a recognition product (SEPIR) capable of restoring MLC responses inhibited by treating stimulator cells with mAb to Class I antigens have been investigated. SEPIR has been found to be present in supernatants of immunological one-way interactions of histoincompatible spleen lymphocytes from naive mice following cultivation for a few hours. It is active in relatively high dilutions. Similarities with cytokines of IL-1, IL-2, or interferon character could not be revealed. Formation of the heat-labile principle is governed by immunologically specific reactions and involves recognition of Class I (but not Class II) HMC antigens by T cells of Lyt-2 phenotype. B cells and Lyt-1+ cells failed to induce formation of the product. SEPIR appears to be a complex of T-cell receptors for Class I antigens with these antigens. The data indicate that in conventionally induced fully incompatible MLC responses a similar product might be formed.

Reconstitution of primary mixed-lymphocyte culture reactions inhibited with class I antibodies by a product of histoincompatible spleen cells

Primary MLC reactions with spleen cells from mice of conventional inbred or congenic origin and incompatible at the entire H-2 or at K- or D-regions could be inhibited by pretreating stimulator but not responder cells with mAb to Class I MHC antigens. Inhibited MLC reactions, initiated in the presence of a product (SEPIR) present in supernatants after short-term cultivations of one-way histoincompatible spleen cells of the same haplotype as MLC cells, could be restored specifically to normal activities. It is suggested that the reconstituting factor represents a product of Class I antigen recognition capable of compensating the prevented recognition of these antigens by MLC responder cells. SEPIR was ineffective in restoring Class II antigen-inhibited MLC responses. Because the product might be formed spontaneously under normal MLC conditions, it had no effect when added to uninhibited MLC cells. Conceivably due to neutralization, SEPIR was also incapable of restoring MLC responses conducted in the continuous presence of Class I mAb. Inhibition of MLC responses and reconstitution with SEPIR depended on the effectiveness of Class I antigen inhibition.

Suppression of experimental allergic encephalomyelitis by retinoic acid

Administration of retinoic acid (RA) prevented the development of experimental allergic encephalomyelitis (EAE) in Lewis rats. RA suspended in corn oil was given for 3 days before the expected onset of the disease to rats immunized with myelin and to controls. The drug suppressed the neurological symptoms as well as the perivascular infiltrates observed in vehicle-treated animals. The results indicate that under these experimental conditions, RA has immunosuppressive activity by interfering with the efferent phase of the immune response.

Spectrum of immunoregulatory functions and properties of human alveolar macrophages

In health, pulmonary alveoli are maintained free of inflammatory responses to inhaled foreign antigens. The specific role of alveolar macrophages (AM) in modulating the local cellular immune response to antigens is controversial. Immunoregulatory function and properties of AM and blood monocytes (MN) were compared. The AM were obtained by bronchoalveolar lavage of healthy volunteers, MN by adherence of peripheral blood mononuclear cells to plastic. These accessory cells were added in increasing ratios to a responder population rendered rigorously accessory cell-dependent by nylon wool adherence and depletion of cells bearing the surface Class II MHC determinant, HLA-DR. At low ratios of mononuclear phagocytes to lymphocytes (less than or equal to 1:10), MN and AM supported significant and comparable blastogenic responses to tetanus toxoid (3H-thymidine incorporation at a 1:10 ratio was 9,697 +/- 2,508 for MN and 8,969 +/- 1,454 for AM, mean cpm +/- SE, n = 9, p = NS) and other antigens. Interleukin-1 (IL-1) activity in supernatants of MN stimulated with lipopolysaccharide (LPS), 10 micrograms/ml, was 115 +/- 28 versus 67 +/- 21 U/ml in supernatants of AM (n = 9, p greater than 0.2). At suboptimal concentrations of LPS, however, MN expressed more IL-1 activity than did AM. The specific mean fluorescence intensity of surface expression of HLA-DR determinants as assessed by flow cytometry was similar for MN and AM. At the higher ratio of 1:2, MN supported 32% increased responses to tetanus toxoid compared with that at 1:5 (p less than 0.05). In contrast, AM at a ratio of 1:2 suppressed lymphocyte response by 69% (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Dendritic cells in human peripheral blood: effective enrichment from the nonadherent cells

Dendritic cells (DC) from human peripheral blood were enriched using a method including adherence on plastic, depletion of phagocytic cells, flotation on density gradient column and panning on antibody-coated surfaces. The course of cell separation was evaluated by characterizing the morphological, antigenic and functional features of the different cell fractions. Using the population depleted of strongly adherent cells as the source, we were able to achieve a cell fraction containing 40-65% of DC (the main contaminants being monocytes and natural killer cells). Functionally these cells were highly stimulatory in autologous mixed leukocyte reaction. On the other hand, cells which primarily adhered well and were detached after overnight culture contained less than 5% of DC (the main contaminants being monocytes) after the same purification protocol. The calculated yields of DC were 1-2 X 10(6) and less than 0.5 X 10(6) from the nonadherent and adherent populations, respectively. Thus we concluded that the adhesiveness of DC from human blood is so weak that they can more efficiently and in a more reproducible way be enriched from the primarily nonadherent cell fraction.

The basis for the immunoregulatory role of macrophages and other accessory cells

Macrophages handle extracellular proteins and secrete diverse bioactive molecules and, therefore, influence the physiology of many tissues. They also have an important immunoregulatory role. The immune response to proteins involves the activation of the T helper subset of lymphocytes. The T helper cell is activated only when it interacts with the protein displayed on the surface of a macrophage or other accessory cell. This interaction involves restrictive proteins encoded in the major histocompatibility gene complex as well as growth-differentiating proteins.

The modulation of class II histocompatibility antigens and 'activated' macrophage determinant in the spinal cord during the development of chronic relapsing experimental allergic encephalomyelitis (CREAE) in the guinea pig--relevance to the induction of remission?

Cryostat sections of spinal cord of guinea pigs with chronic relapsing experimental allergic encephalomyelitis (CREAE) were stained with monoclonal antibodies recognising a Strain 13-specific Ia epitope, a non-strain-specific Ia antigen and an 'activated' macrophage determinant. It was found that both Ia antigens and the 'activated' macrophage determinant, observed on infiltrating cells within both perivascular and meningeal compartments, appeared to be modulated during the course of CREAE. This correlated with the neurological symptoms of the disease. Blood vessels and 'glial' cells expressed both Ia determinants. 'Glial' cells also expressed the 'activated' macrophage antigen. These antigens were modulated with the course of the disease.

The quantitation of HLA-DR expression on human cells using immunocytochemistry

An immunocytological method that can be used to quantify the comparative expression of Class II HLA-DR antigens on human cells has been developed. Tissue sections or cytospins are incubated with the monoclonal antibody RFDR1 (anti-HLA-DR), conjugated to the enzyme glucose oxidase (GO). The bound McAb is identified by incubation with the substrate beta-D-glucose and capture of the reducing equivalents generated by a tetrazolium salt forming an insoluble formazan. Under standard conditions the amount of formazan precipitated is proportional to the amount of McAb bound to the cells or tissue and thus the amount of HLA-DR expressed. The reaction has been quantified both by spectrophotometry (on tissue sections) and by microdensitometry (on cell spreads). Computer analysis has been used to relate density of HLA-DR expression to cell area. Repeated 'blind' measurements by separate investigators have confirmed the reproducibility of the results. It is suggested that this method adds a new dimension to immunohistological/cytological analysis of tissues and single cells.

Nephropathic cystinosis: immunohistochemical and histopathologic studies of cornea, conjunctiva and iris

Specimens of a cornea, conjunctiva and iris were removed at the time of penetrating keratoplasty in a case of nephropathic cystinosis. Immunohistochemical studies revealed the presence of class II antigens on the stromal keratocytes of the cornea and the vascular endothelial cells, pericytes and fibroblasts of the conjunctiva. In addition, there were thinning and focal breaks in Bowman's membrane. Both of these findings may have contributed to the severe photophobia and blepharospasm seen in patients with longstanding cystinosis.

Immunoresponses to Neisseria meningitidis epitopes: immunomodulation by meningococcus B acts on more than one meningococcal surface epitope

Neisseria meningitidis group B strain M986 (serotypes 2a, 7) (NMB) elicits a specific primary antiphosphorylcholine immune response in mice but not a secondary response. The ability of other serotype and serogroup meningococci to induce similar primary responses in mice was studied, as was the immunogenicity of trinitrophenyl coupled NMB (TNP-NMB) in primary and secondary antitrinitrophenyl responses. Except for NMB, all other strains tested (three serogroup B and one serogroup A meningococcal strains) were found to be very poor phosphorylcholine immunogens. TNP-NMB, however, though proving to be a very good TNP antigen, was only a weak phosphorylcholine antigen. Priming NBF1 female mice with TNP-NMB one month or more before challenging them with the same antigen induced a strong depression of anti-TNP response in the subsequent challenge. However, this effect was not observed with Xid NBF1 male mice. Furthermore, priming mice with NMB weakly affected the anti-TNP response, but greatly depressed the antiphosphorylcholine response, after TNP-NMB challenge. In addition, whereas apparently only one TNP-specific B cell subpopulation was responding in unprimed mice challenged simultaneously with TNP-NMB and TNP-Ficoll (non-additive response), priming mice with NMB appeared to facilitate the independent activation of two different TNP-specific B cell subpopulations (additive response).

Modulation of monocyte complement synthesis by interferons

Recombinant Escherichia coli-derived gamma-interferon has been shown to stimulate synthesis of the second component of complement (C2), factor B and C1 inhibitor, but to inhibit synthesis of the third component (C3). alpha- and beta-interferons stimulate synthesis of factor B and C3 inhibitor, inhibit C5 synthesis but do not alter synthesis of C2. alpha- and beta-interferons act synergistically with gamma-interferon to enhance both factor B and C1-inhibitor synthesis.

Functional characteristics of in vitro generated macrophages: a transient refractory state precedes reinducibility of a spatially restricted, possibly contact-dependent, cytostatic mechanism

Adherent layers of macrophages (M phi-c) generated in vitro from splenic precursors previously have been shown to inhibit proliferation of normal and neoplastic cells by mechanisms that do not involve the secretion of significant quantities of prostaglandins, peroxides, or proteases. In the current report, it is demonstrated that the effective range of the cytostatic effect of adherent M phi-c is so low that cytostasis can be circumvented by preventing the target cells from settling to the adherent layer by incubating the cultures of targets and M phi-c on a rocking platform. Despite the paucity of production of inhibitory mediators, the M phi-c do produce sufficient IL-1 to restore IL-2 production capacity to macrophage-depleted lymphocyte populations. The cytostatic activity of the M phi-c is an inducible event and remains for several days in the continuous presence of mitogen-activated lymphocytes or LPS + lymphokines. Once the activators are removed the cytostatic activity rapidly declines, reaching background levels in 24-48 hr. Maximal cytostatic activity can be reinduced but only 48 hr or longer after the primary activators were removed. A transient period in which the M phi-c are refractory to reactivation can be demonstrated to exist for 1-2 days after removal of the primary activators.

Variable severity and Ia antigen expression in streptococcal-cell-wall-induced hepatic granulomas in rats

We have previously reported that a single intraperitoneal injection of an aqueous suspension of group A streptococcal cell wall (SCW) fragments induces extensive hepatic granulomas in LEW/N female rats, but not in F344/N female rats. To further understand the mechanisms underlying these differences, we compared granuloma development and class II major histocompatibility complex antigen (Ia) expression in histocompatible LEW/N, F344/N, and CAR/N female rats in response to SCW fragments of four different average molecular sizes. In LEW/N female rats, the smallest fragments (less than 5 megadaltons) induced the most severe hepatic inflammatory disease, with development of widespread granulomas composed of macrophages, lymphocytes, and a peripheral rim of fibroblasts. The largest fragments (greater than 500 megadaltons) induced equivocal disease. Fragments of intermediate size induced granulomas of intermediate severity. The extent of granuloma development, the intensity of Ia antigen expression, and the amount of SCW antigen deposited in the liver qualitatively paralleled each other. In contrast, injection of the most granulomagenic SCW fragments into F344/N and CAR/N rats did not induce granulomas. Although these rat strains are histocompatible with the LEW/N (i.e., RTL.1) strain, hepatic Ia antigen expression in these strains was not increased significantly above basal levels. The amount of SCW antigen in the livers of the resistant rat strains appeared similar to the amount in the susceptible LEW/N strain. These data indicate that granuloma development is dependent on the size of the SCW fragment and host genetic background and that Ia expression directly parallels the severity of the hepatic disease. In addition, the data suggest that non-major histocompatibility complex genetic loci play a major role in regulating the development of the hepatic disease.

Monocyte (macrophage)-specific antibodies in patients with systemic lupus erythematosus (SLE)

Antibodies reactive for monocytes (macrophages) were found in the sera of patients with systemic lupus erythematosus (SLE). These antibodies were present in both IgG and IgM fractions and worked under both warm (37 degrees C) and cold (4 degrees C) conditions. These antibodies were specific for monocytes, because cytotoxic antibodies for monocytes were absorbed with monocytes, but not with T cells, B cells, and granulocytes. Furthermore, their specificity is also different from anti-HLA-DR antibody. The presence of these antibodies correlated with the activity of disease. They were found in 12 of 14 active SLE and 7 of 16 inactive SLE patients. The treatment of normal monocytes with these SLE sera and complement resulted in the depletion of their accessory function for T-cell activation and their phagocytic activity. In the previous paper, we reported that the accessory function of monocytes for T-cell activation was impaired in SLE patients. These results suggest that monocyte-specific antibodies play an important role in the pathogenesis of SLE through disturbing the monocyte regulatory function for immune responses.

Antigenic and cytochemical characterization of cells adhering to intrauterine contraceptive devices

Eighteen copper intrauterine devices (IUDs), removed after 25 months of use, were examined to evaluate cells adhering to them (IAC). By means of monoclonal antibodies, the antigenic phenotype of IAC was studied, along with some IAC cytochemical properties. Sixty percent of IAC were identified as granulocytes based on morphological, cytochemical, and antigenic characteristics. A small proportion of IAC were shaped like large foreign-body macrophages, with multiple picnotic nuclei, and diffused alpha naphthyl acetate esterase (ANAE) activity. Some IAC identified as macrophages from a morphological view point also showed dipeptidyl-diaminopeptidase IV (DAPIV) reactivity, previously described only in T-helper lymphocytes. Most IAC identified as macrophages reacted with the monoclonal antibodies OKM1 and HLA-DR, and showed ANAE activity in the form of small multiple granules. The hypothesis that IUD-adhering macrophages with an ANAE+, DAPIV+, OKM1+, and HLA-DR+ phenotype could play a role in the inactivation of spermatozoa can be proposed.

Glucocerebrosidase deficiency and lysosomal storage of glucocerebroside induced in cultured macrophages

A cell culture model stimulating the genetic deficiency of glucocerebrosidase has been developed, utilizing macrophages and conduritol B epoxide (CBE), the specific irreversible inhibitor of the enzyme. Rat peritoneal macrophage glucocerebrosidase was completely inhibited when cells were treated with 10 microM CBE for 16 h or 100 microM CBE for 2 h. The t1/2 of inactivation was 30 min at 10 microM concentration. When cells were washed free of CBE, the enzyme activity reappeared linearly with time, reaching 50% of control activity 48 h after removal of the inhibitor. CBE-treated macrophages have normal phagocytic activity toward [3H]glycine-coupled latex beads and a normal number of mannose receptors. CBE was found to have no effect on other lysosomal enzymes. When [14C]glucocerebroside, encapsulated in multilamellar liposomes with alpha-D-mannopyranoside covalently coupled to the surface, was fed to glucocerebrosidase-depleted macrophages, the radiolabelled glycolipid accumulated and was undegraded. Subcellular fractionation on a Percoll density gradient demonstrated that the stored glucocerebroside in the CBE-treated macrophages was localized in lysosomes.

Induction of in vivo helper activity for murine antibody responses by macrophages pulsed with ovalbumin-monomethoxypolyethylene glycol (OA-mPEG) conjugates

Conjugates of protein antigens with an optimal number of monomethoxypolyethylene glycol (mPEG) chains of an appropriate molecular weight had been shown to suppress murine IgE responses to the unmodified antigen. To investigate the possibility that the tolerogenic capacity of these mPEG conjugates is attributable to a defect in macrophage (M phi) presentation of their antigenic determinants, the activity of ovalbumin (OA)-mPEG conjugates when pulsed onto mouse peritoneal adherent cells (M phi) was compared in this study with their activity in solution. Surprisingly, in contrast to the suppressogenic capacity of mPEG conjugates in solution, the OA-mPEG pulsed M phi appeared to exert a helper effect when injected intraperitoneally (ip), i.e., after subsequent immunization with dinitrophenylated OA (DNP3-OA) in Al(OH)3, the mice showed accelerated IgE and IgG1 antibody responses to OA and DNP. However, when M phi were exposed to limiting concentrations of OA or OA-mPEG, markedly higher concentrations of OA-mPEG were required to yield pulsed M phi, exerting a significant helper effect. It was concluded that although M phi were capable of presenting the OA determinants of OA-mPEG conjugates to helper T (Th) cells, the preparations of modified antigen were presented less effectively than native OA.

Human mononuclear cell in vitro activation in microgravity and post-spaceflight

The results of postflight and inflight human in vitro lymphocyte experiments have been reviewed. The cumulative data indicate that mitogen-stimulated T-cell proliferation is blunted following short-duration missions. Since similar responses may also be obtained following exposure to non-spaceflight stressors (hypoxia and academic stress), it is unclear if microgravity per se aggravates this response. Our studies indicate that stress-induced impaired PHA- and PWM-stimulated activation can be detected within the first 24 hours in culture at the level of protein synthesis. While the mechanism for neuroendocrine-mediated blunted mitogen stimulated T cell proliferation has not been elucidated, it is not aggravated by autologous plasma and does not require changes in mononuclear cell subpopulations. While prior studies indicate lymphocyte activation is influenced by altering G forces on in vitro cultures, impaired cellular interactions or suboptimal microenvironments related to reduced cell densities in microgravity may contribute to the greatly impaired mitogen stimulated proliferation responses observed on Spacelab flights. It will be necessary to perform lymphocyte functional assays on crewmembers during spaceflight to determine to contribution of microgravity per se on altered human immune competence.

The effect of doxycycline on polyvinylpyrrolidone-induced granuloma formation in the rat liver

The tetracyclines specifically inhibit mitochondrial protein synthesis when present at the same low concentrations as used for their antibacterial action. Inhibition of mitochondrial protein synthesis leads to decrease in the oxidative energy-generating capacity of cells. Therefore, the presence of tetracyclines may result in proliferation arrest. In the present study we show that continuous intravenous administration of polyvinylpyrrolidone (PVP) induces the formation of granulomas in the normal rat liver; the rats usually die within 2 weeks of continuous PVP treatment. Athymic (nude) rats appear to be more resistent to the deleterious effects of PVP as they survive the treatment for at least 5 weeks. Although the livers of the PVP-treated nude rats are heavily infiltrated with phagocytic cells, they seldom show granulomas. Reconstitution of nude rats with syngenic thymocytes leads, on the other hand, to extensive granuloma formation. Normal rats treated continuously with PVP plus doxycycline, however, all survive, their livers showing only a few very small granulomas and the normal low number of phagocytic cells. We conclude that the formation of granulomas induced by PVP is a process which is mediated by T-lymphocytes. Because doxycycline prevents this kind of granuloma formation it seems likely that doxycycline not only impairs the proliferation and differentiation of T-lymphocytes but also of monocytes and macrophages.

Virus-induced immunosuppression

Infection with a variety of viruses results in the suppression of the host's immune system. Several mechanisms thought to be responsible for this effect are discussed: infection and alteration of lymphocytes and macrophages, production of soluble suppressor factors, and the induction of suppressor cells. The clinical significance of virus-induced immunosuppression is also discussed.

Antigen presentation by hapten-specific B lymphocytes. III. Analysis of the immunoglobulin-dependent pathway of antigen presentation to interleukin 1-dependent T lymphocytes

The ability of antigen-specific murine B lymphocytes to present antigen to a normal (nontransformed) antigen-specific, interleukin (IL)1-dependent T cell clone and to heterogeneous T lymphocytes was investigated. Hapten-specific lymphocytes present protein antigens to both the D10G.4.1 T cell clone and heterogeneous immune T cells. When the antigen bears an epitope recognized by the specific B cell, the subsequent presentation of this antigen is 10(2)-10(4)-fold more efficient, as compared to the same, but nonhaptenated protein. The requisite B lymphocyte binds hapten, is radiosensitive and is nonadherent to plastic. The hapten-specific antigen presentation is blocked by antibodies to the surface Ig receptor, while the presentation of unmodified protein is unaffected. These observations are identical to our findings in studies of B cell antigen presentation to T-T hybridomas and therefore demonstrate the generality of the immunoglobulin-dependent pathway of presentation. However, in contrast to the results with T-T hybridomas, the specific B lymphocytes are necessary, but not sufficient, to activate IL 1-dependent T cells. A third cell is required for both B lymphocyte immunoglobulin-dependent and nonspecific antigen-presentation. This cell is radioresistant, plastic adherent and of low density. The requirement for this third cell can be circumvented by supplementing cultures with highly purified IL 1. These results demonstrate that the remarkably efficient ability of B lymphocytes to present antigen is operative with factor-dependent T lymphocytes. Furthermore, conventional accessory cells also appear to play a role in this process, which is consistant with their known requirement in antigen-specific T-B interactions in the generation of antibody responses.

Reduced cellular immunity to varicella zoster virus during treatment for acute lymphoblastic leukemia of childhood: in vitro studies of possible mechanisms

To determine the effect of antileukemic therapy on preexisting immunity to varicella zoster virus, we studied 20 children with acute lymphoblastic leukemia maintained in complete continuous remission for greater than 1 year. Cellular immunity was tested by lymphocyte proliferation in response to varicella antigen. Antiviral antibody was measured using the fluorescent antibody to membrane antigen technique. Reduced lymphocyte proliferation was found in 9 of 16 seropositive patients when compared to an age-related control group. On the other hand, antibody titers in patients receiving chemotherapy remained positive and were essentially unchanged from pretreatment values. Shingles occurred in two of nine children with diminished and none of seven patients with normal cellular immunity, suggesting that proliferative responses to varicella antigen may have predicative value in identifying patients at risk for viral reactivation. Additional studies were done to determine if defective antigen presentation or reduced lymphocyte responder-cell frequency could account for the subnormal proliferative responses. Intact presentation of varicella antigens by patient mononuclear cells to parental, virus-specific T-cell blasts suggested that antigen processing was not defective. However, varicella-specific responder-cell frequencies measured by limiting dilution analysis were found to be depressed in most patients, including some with normal proliferative responses. Our findings indicate that therapy for acute lymphoblastic leukemia in children can be associated with depressed cell-mediated immunity to varicella zoster virus even though patients remain seropositive. Further studies suggest that while monocyte-mediated antigen presentation remains intact, virus-specific lymphocyte numbers decline and probably contribute to decreased cellular immunity to varicella zoster virus in children being treated for leukemia.

Spleen and lymph node cell populations, in vitro cell proliferation and interferon-gamma production during the primary immune response to Toxoplasma gondii

An animal model for the study of transient lymphadenopathy-splenomegaly during toxoplasmosis is presented. Injection of CBA/J mice with the low virulent, cyst-forming strain of Toxoplasma gondii (Pe strain) induces a three to four fold increase in weight and cellularity of spleen and lymph nodes with peak changes at 30-50 days after infection. The spleen displays marked haemopoiesis, a 30 fold increase in mononuclear phagocytes, and a two fold increase in Lyt2+ lymphocytes. Lymph nodes show a five fold increase in mononuclear phagocytes and a four and a half fold increase in Lyt2+ T cells. The increase in mononuclear phagocytes significantly alters T cell/macrophage ratios and this is associated with decreases in in vitro cell proliferation to mitogen and toxoplasma antigen. The relationship between alterations in cell balance of mononuclear phagocytes and T cell subsets and the expression of transient immune dysfunction can now be examined by modulating changes in these cell types.

Expression of MHC class II antigen, interleukin-2 receptor, transferrin receptor and gp 40/80 glycoprotein during different phases of a normal PHA-driven lymphocyte activation in vitro

This study characterizes the temporal profile of MHC class II antigen, interleukin-2 receptor, transferrin receptor and gp 40/80 glycoprotein lymphocyte activation markers in relation to each other during different phases of PHA-dependent cellular activation in vitro. Binding of these monoclonal lymphocyte activation-probes was visualized by the avidin-biotin-peroxidase complex method. Maximum PHA-dependent MHC class II antigen expression of 27 +/- 3% was observed on culture day 1, but later no significant differences were observed in MHC class II antigen expression between PHA-driven or culture media-containing control cultures. On the contrary, interleukin-2 receptor (78 +/- 6%) and transferrin receptor (75 +/- 5%) expression reached a maximum on culture day 3, coinciding with a maximum proliferative response. On culture day 5, when 3H-thymidine incorporation was already on the decline, gp 40/80 glycoprotein reached a maximum PHA-dependent expression of 78 +/- 2%, which differed significantly from interleukin-2 receptor (60 +/- 8%, p less than 0.05) and transferrin receptor (51 +/- 8%, p less than 0.01) expression. This study suggests that MHC class II antigen, interleukin-2 receptor, transferrin receptor and gp 40/80 glycoprotein, although all of them are lymphocyte-activation markers, differ as to the chronological sequence of their appearance and disappearance. Their combined use in lymphocyte-activation marker profile assay therefore gives valuable information about the lymphocyte activation state.

Histochemical demonstration of mycobacterial antigen, specific antibody and complement in the lesions of tuberculosis

Lesions were studied histochemically for mycobacterial antigen, its specific antibody and complement in 31 patients with recently-diagnosed tuberculosis. The results were related to a histological spectrum that correlated with bacterial load. The form, localization and persistence of antigen were found to be as significant as the amount. In high-resistant cases, the antigen was mainly soluble, a form which was non-toxic when ingested by macrophages but associated with tissue damage when bound to connective tissue. There was no close contact between plasma cells and antigen. However, in cases with moderate resistance, where plasma cells and antigen intermingled freely, necrosis with karyorrhexis and polymorph infiltration was associated with deposition of antigen, antibody and complement at the same sites, indicating the probability of immune complex formation in these lesions. In low-resistant cases, extensive necrosis was attributed partly to high levels of extracellular antigen. The correlation between immunological circumstances and the manifold forms of necrosis validated these forms as the basis for a histological spectrum in tuberculosis.

Participation of interleukins in synergistic effect of Bu-WSA on concanavalin A-induced DNA synthesis in mouse splenic lymphocytes

Butanol-extracted water-soluble adjuvant (Bu-WSA) obtained from Bacterionema matruchotii was mitogenic to murine splenic B lymphocytes, but not T lymphocytes. When murine splenic cells were cultured in the presence of Bu-WSA and concanavalin A (Con A) together, [3H]thymidine uptake of the culture cells synergically increased. The mechanism of the synergy of Con A and Bu-WSA and the participation of interleukin (IL) 1 and 2 in the synergy were studied. The proliferation cells in the synergy were Lyt-1+23- lymphocytes. Ia-positive accessory cells were required for the response. When separated cell populations and Marbrook-type culture vessels were used, a mixed cell population of T lymphocytes and B lymphocytes or macrophages (M phi) produced some active factor(s) after co-stimulation by Con A and Bu-WSA, and the factors enhanced DNA synthesis of another Con A-activated T lymphocyte population. Supernatants obtained from the spleen cell cultures or the mixed cell cultures with T lymphocytes and M phi in the presence of Con A and Bu-WSA contained greater amounts of IL-1 and IL-2 than those from cultures containing Con A or Bu-WSA alone. An addition of exogenous IL-1 or IL-2 to spleen cell cultures with Con A resulted in a proliferative response like that obtained through co-stimulation by Con A and Bu-WSA. These results suggest that the synergistic effect of Con A and Bu-WSA on the proliferative response in murine splenic cells is sustained by the enhancement of production of these T-lymphocyte growth factors.

Regulation of the cytotoxic activity of alloreactive cytotoxic T lymphocytes by helper cells and lymphokines

The cytotoxic activity of alloreactive cytotoxic T lymphocytes (CTL) was maintained and augmented by transferring cells from a 5-day mixed lymphocyte culture MLC into a host culture (HC) containing indomethacin, freshly explanted normal spleen cells, and peritoneal cells which were syngeneic to the MLC cells. The MLC cells used in the transfer experiments were generated by culturing untreated H-2b splenic responders with irradiated H-2d stimulators, or were generated by culturing Lyt-2-depleted H-2b splenic responders with irradiated H-2d stimulators. The allo-CTL were found to be derived from the donor MLC (first culture) when unfractionated MLC cells were transferred into a host (second) culture and incubated for 5 days. In contrast, the allo-CTL were derived from host culture cells when Lyt-2-depleted MLC cells were transferred and the combined cultures incubated for 5 days. In the former case, the augmentation of MLC-derived cytotoxicity did not result from nonspecific expansion of all donor T cells; instead it was mediated by lymphokine(s), distinct from IL-2, produced by helper T cells generated in host culture, which appeared to selectively expand the antigen-specific CTL or to increase the cytotoxic activity of these CTL. The helper T cells were Thy-1+, L3T4+, and Lyt-2-. These findings indicate that antigen-nonspecific help was provided by helper cells or helper factors (lymphokines) generated in the host culture, which maintained and augmented the cytotoxic activity of the fully generated allo-CTL. This helper effect was also seen in the induction of primary allo-CTL responses which could be generated with fewer stimulating cells and with a stronger cytotoxic response at different R/S ratios tested. The generation of allo-CTL in second culture following transfer of Lyt-2-depleted MLC cells to host cultures appears to have involved antigen carryover from the MLC; however, antigen carryover alone was not sufficient. It appears that in the absence of Lyt-2+ suppressor T cells, antigen-specific help might be generated in donor cultures (Lyt-2-depleted MLC) which promoted or recruited the generation of antigen-specific CTL in host culture.

A prostaglandin-mediated suppressive activity of cord as compared to maternal or other adult adherent cells in OKT3 antibody-induced proliferation

In a previous study we reported that cord blood lymphocytes show lower OKT3 responses as compared to their mothers and to other, unrelated adults. In the study reported here, we investigated the interactions between lymphocytes and adherent accessory cells in OKT3-stimulated cultures of newborn (cord), maternal, and other adult peripheral blood mononuclear leukocytes (PBML) and determined the following. (1) Removal of adherent cells (AC), by two cycles of plastic adherence or by nylon wool columns, impaired the OKT3-induced proliferation of maternal/adult cells, but significantly enhanced the OKT3 responsiveness of cord cells. (2) Addition of indomethacin, and other prostaglandin (PG) synthesis inhibitors, caused a more than twofold augmentation of cord PBML OKT3 responses, but had only a small, if any, enhancing effect on maternal/adult PBML. Cord PBML cultures deprived of AC were no longer enhanced by indomethacin. (3) Exogenous PGE2 (1.4 X 10(-6) through 1.4 X 10(-9) M) strongly inhibited OKT3-induced proliferation of maternal, cord, and adult PBML, at a wide range of antibody concentrations (5-100 ng/ml). However, an obvious difference in the extent of PG-mediated inhibition was observed among these three populations, and the order of PG sensitivity, from most to least sensitive, was cord greater than maternal greater than adult. (4) Purified interleukin-1 (IL-1) could not replace the accessory function of AC in the OKT3-induced proliferation of maternal/adult lymphocytes. In contrast, IL-1 increased by greater than 50% the OKT3 responsiveness of cord PBML in the absence, but not in the presence, of cord monocytes. Our observations strongly argue for a distinct, predominantly suppressive function of cord monocytes as compared to maternal/adult monocytes in OKT3-induced mitogenesis, and indicate prostaglandins as major mediators of this suppression.

Cell-mediated inhibition of proliferation and activation of alloreactive cytotoxic lymphocytes: maintenance of response potential of precursors and dissociation between proliferation and effector function of activated cytotoxic lymphocytes

Adherent layers of macrophages (M phi-c) generated in vitro from splenic precursors inhibit lymphoproliferative responses to mitogen and to alloantigen without inhibiting the production of interleukin-2 (IL-2). Analysis of spleen cells stimulated for 48 hr in the presence of M phi-c indicated that both blastogenesis (increased cell mass) and expression of IL-2 receptors (7D4 determinants) were reduced. Analysis of BrdU incorporation (frequency of S-phase cells) and total cellular DNA revealed that the M phi-c inhibited the progression from G1 to S phase of cell cycle. The M phi-c not only inhibited the proliferative response to alloantigen but also prevented the generation of alloreactive cytotoxic T cells. The M phi-c were shown not to inhibit CTL responses by eliminating the stimulators or by inactivating precursors or inducing suppressors. The M phi-c were affecting the induction of CTL activity since the M phi-c did not affect the expression of cytolytic activity by activated CTL. The M phi-c did inhibit the proliferation of the activated CTL, suggesting that although cytolytic activity can be expressed in G1 phase of cell cycle, the activation of cytolytic activity in CTL-P may require a G1 to S phase transition. The cells recovered from 5-day MLC incubated in the presence of M phi-c were fully capable of generating a subsequent CTL response. This is in contrast to cells recovered from unstimulated cultures (no M phi-c) which have lost the ability to generate CTL responses. The M phi-c therefore prevent the generation of CTL responses in a totally reversible fashion, so as to allow activation and proliferation of CTL-P which have been removed from the influence of the M phi-c. These observations are discussed in the context of the currently hypothesized role of tissue macrophages in microenvironmental regulation.

Synergistic action of gamma interferon and catalase to reverse the suppressive effect of peritoneal macrophages on concanavalin A-induced lymphocyte proliferation

The suppressive effect of normal rat peritoneal exudate cells (PEC) on concanavalin A (Con-A)-induced lymphocyte proliferation was studied. Partial suppression of proliferation was obtained by adding 3% PEC and complete suppression was observed with 6% PEC. The suppressive effect was mediated by W3/25+ plastic-adherent macrophages, which constitute about 60% of normal PEC. Addition of PEC prior to, simultaneously with, or 24 h after, but not 48 h after, the stimulation of lymphocytes with Con A resulted in suppression. Suppressed cultures produced normal or slightly increased amounts of interleukin 2 (IL-2), but the expression of the IL-2 receptor on lymphocytes was decreased. Pre-exposure of PEC to gamma interferon (IFN-gamma) resulted in decreased suppression, whereas IFN-gamma added simultaneously with the lymphocytes had no effect. Catalase reversed PEC-induced suppression and significant synergistic effects were recorded when combined with IFN-gamma. Even completely suppressed cultures were effectively protected from suppression. Indomethacin and combinations of indomethacin with catalase or IFN-gamma did not result in additional protection from PEC-mediated suppression.

The phylogeny of macrophage function: antigen uptake and degradation by peritoneal exudate cells of two amphibian species and CAF1 mice

Equal numbers of thioglycollate mobilized peritoneal exudate cells (PEC) of the newt, Notophthalmus viridescens, the South African clawed toad, Xenopus laevis, and CAF1 mice were compared with respect to their capacity to take up and degrade soluble 14C-ovalbumin (OVA). PEC of the newt failed to take up the labeled antigen, while those of the toad incorporated only one-half as much as those of the mice. Moreover, the toad PEC degraded only 42% of the immunogen which was taken up, while PEC of the mice degraded 78% of the immunogen they had ingested during the 60-min period. Paraformaldehyde treatment of the PEC prevented antigen uptake, while chloroquine treatment prevented degradation with both species, and thus, active processes were involved. While newt PEC were unable to ingest soluble OVA, they were able to ingest and degrade OVA conjugated to sepharose during the same time period. The failure of primitive vertebrates to respond immunologically to soluble proteins appears to be due to their failure to ingest soluble immunogen.

Expression of HLA-DR antigen on retinal pigment epithelial cells in retinitis pigmentosa

Class II (HLA-DR) antigens are cell surface molecules that play a major role in the initiation and perpetuation of immune responses. Although most cells do not constitutively express class II antigens, selected cells can be stimulated to do so in some immunologically mediated disorders. When retinal pigment epithelial cells were evaluated by either immunoperoxidase or immunofluorescent staining of frozen eye sections from normal individuals, HLA-DR antigens were not detected. In contrast, retinal pigment epithelial cells from two patients with retinitis pigmentosa did express HLA-DR antigens. These findings demonstrated that at some time during the course of retinitis pigmentosa, the retinal pigment epithelial cell is activated to express HLA-DR.

Presentation of alloantigens by host cells

Presentation of alloantigens by host cells has been examined in vivo by means of a murine cell transfer system. Primary (1 degree) hosts were activated by the i.p. administration of allogeneic spleen cells and their spleen or peritoneal cells were transferred into syngeneic secondary (2 degrees) hosts 3 days later. Sensitization of 2 degrees hosts was assessed by their ability to reject donor strain skin grafts prematurely. The transferred cells were routinely depleted of T lymphocytes. We show that (a) 5 X 10(7) spleen and 3 X 10(6) peritoneal cells consistently caused marked accelerated graft rejection; (b) this effect was antigen specific and observable in all strain combinations studied; (c) it was caused by the active sensitization of 2 degrees hosts, but not by contaminating donor strain cells; (d) the cells involved were plastic adherent and viability was not a requirement; and (e) both class I and II, but not minor, histocompatibility antigens played a role in this model. We conclude that presentation of alloantigens by host antigen-presenting cells can be a potent route of allosensitization.

Antigenic requirements for T-cell activation: reconstitution of a functional antigen from an inactive peptide portion of an antigen conjugated to protein carriers

The structural features of an antigenic peptide required for T-cell activation were examined by a novel approach: an active antigen was constructed from an inactive peptide portion of the original antigen by conjugating it to various proteins. An eicosapeptide, peptide 8, representing residues 103-112 of the tobacco mosaic virus protein (TMVP), was utilized as the model antigen for these studies. While peptide 8 was able to stimulate, in vitro, T-cells from peptide 8 primed mice, synthetic peptides representing various portions of peptide 8 were unable to activate these cells. Although the amino-terminal undecapeptide of peptide 8 (residues 93-103 of TMVP) was unable to activate T-cells from peptide 8 primed mice, conjugates which consisted of this undecapeptide coupled to certain proteins were capable of inducing antigen-specific proliferation of these T-cells. These results identify two structural antigenic features essential for T-cell activation: a T-cell-recognizable epitope within the amino-terminal undecapeptide of peptide 8 and a second region provided by the carboxy-terminal half of peptide 8 or by protein carriers. Potential roles for this second region include providing a site for antigen interaction with Ia molecules on the antigen-presenting cell or, alternatively, providing amino acids important in stabilizing the binding of the T-cell antigen receptor. The results suggest that the recognition of this second region exhibits only a limited specificity.

Antigen-presenting cell function of dendritic cells and macrophages in proliferative T cell responses to soluble and particulate antigens

The capacity of dendritic cells (DC) and macrophages (M phi) to present soluble and particulate antigen was tested in an ovalbumin (OVA)-specific T cell proliferation assay. In a comparative investigation we found that both DC and M phi were able to present soluble OVA, but that only M phi could present insolubilized OVA to T cells. DC were found to be able to present OVA in collaboration with M phi. The failure of DC to present insolubilized OVA is probably caused by their inability to endocytose these antigens. DC appeared not to endocytose substantial amounts of soluble OVA either. In contrast to M phi, antigen presentation by DC is not blocked by lysosomotropic drugs. Taken together, these observations suggest that DC can present soluble protein antigens without intracellular degradation.

Human Peyer's patches: an immunohistochemical study

We have used immunoperoxidase techniques to characterise the Peyer's patches in human terminal ileum. The mantle zones of the B cell follicles in human Peyer's patches were surrounded by B cells which did not express surface IgD but which mostly expressed surface immunoglobulin of the IgM and/or IgA1 isotype. Few cells expressing surface IgG or IgA2 were detected. Cells with cytoplasmic immunoglobulin of all isotypes except IgD were present in the dome regions of the Peyer's patches as well as in the lamina propria. There was little evidence of traffic of immunoglobulin synthesising cells across the high endothelial venules. T cells were seen to surround the lymphoid follicles. They were most concentrated on the serosal aspect around the high endothelial venules. Cells with macrophage-like morphology were present in both the lamina propria and the dome region of the follicles; those in the lamina propria containing lysozyme and those in the dome region S100 protein. The results are discussed in relation to the generation and dissemination of antibody producing cells in human gut.

Puromycin aminonucleoside nephropathy: ultrastructure, glomerular polyanion, and cell surface markers

Puromycin aminonucleoside nephropathy with heavy proteinuria and oedema was induced in rats by 10 consecutive daily subcutaneous injections of aminonucleoside (1.67 mg/100 g of body weight). The main ultrastructural lesions were vacuolation of podocytes and total fusion of foot processes with loss of colloidal iron-reactive polyanion layer on the epithelial surface adjacent to the basement membrane. On the other hand the outer surface of podocytes and intravacuolar granular substance stained with colloidal iron. In scanning electron microscopy of freeze-fractured tissue the swollen podocytes and the urinary spaces displayed granular and filamentous precipitates. Seven cell surface antigens were examined by indirect enzyme immunohistochemistry with a series of MRC OX monoclonal antibodies. Glomeruli of control rats exhibited rare isolated Ia- positive endocapillary cells, possibly monocytes; these elements were significantly reduced in puromycin aminonucleoside nephropathy but there was an increase in Ia- positive cells in the cortical interstitium. Control kidneys harboured scanty interstitial T lymphocytes. These latter, especially the T8- positive cytotoxic/suppressor subpopulation, were markedly augmented in puromycin aminonucleoside nephropathy. The expression of class I histocompatibility antigens and of differentiation antigens (Thy 1) was not altered by aminonucleoside.

Infection of mice with lactic dehydrogenase virus prevents development of experimental allergic encephalomyelitis

A significant reduction in the incidence of experimental allergic encephalomyelitis (EAE) in SJL/J mice was observed when mice were infected with lactic dehydrogenase virus (LDV) 14 days before, on day 0, or 3 days after immunization with spinal cord homogenate. These results are discussed in terms of the selective infection by LDV of I-region-associated antigen- (Ia) positive macrophages.