Cutaneous basophil hypersensitivity uncovered in the cell transfer of classical tuberculin hypersensitivity.

Cellular transfer of cutaneous basophil hypersensitivity (CBH) was studied. Guinea pigs immunized for CBH with incomplete Freund's adjuvant (IFA) provided cells which could transfer delayed and basophil-rich reactions in skin tests of recipients. Guinea pigs immunized with complete classical tuberculin-type delayed hypersensitivity reactions (DH), which are characteristically devoid of basophils. However, recipients of cells from donors with DH, surprisingly, were found to have delayed skin reactions containing large basophil infiltrates which were lacking in the donors. Thus, recipients of classical cell transfers of tuberculin-type DH had delayed reactions which resembled CBH. Control experiments verified that the cell transfer of CBH from donors with DH was due to passive transfer with live cells and not transfer of contaminating humoral factors or active sensitization of recipients. It was concluded that cutaneous basophil responses were suppressed in CFA-immunized donors and expressed in cell transfer recipients. Cells from donors immunized with CFA were enriched for nonadherent and nonimmunoglobulin-bearing lymphocytes by passage through nylon wool columns, and these cells transferred conjugate specific CBH reactions. It was concluded that cells mediating these transfers were probably T cells. The finding of basophils in cell transfers of DH and a variety of other findings suggesting complex regulation of basophil numbers in tissue lead to the conclusion that the term CBH be used to simply describe a basophil-containing skin reaction.     

Anti-T cell monoclonal antibodies in vivo. II. Modulation of acute and chronic experimental allergic encephalomyelitis (EAE) in guinea pigs

To determine the effects of anti-T cell monoclonal antibody-induced systemic T cell depletion in neuro-autoimmune disease, we studied the in vivo effects of 8BE6, a mouse anti-guinea pig (GP) pan-T cell monoclonal antibody, on the course and immunopathology of the disease model experimental allergic encephalomyelitis (EAE) in adult Strain 13 GP. Central nervous system (CNS) tissues were studied by routine histology and by an immunoperoxidase staining technique using monoclonal antibodies to T cells, IgM, and macrophages. From 3 days before to 10 days after sensitization with GP spinal cord and complete Freund's adjuvant, the GP were given one or two i.p. doses of 3.4 mg 8BE6 or MOPC 21, the parent mouse myeloma ascites, or normal saline. Eighteen of 18 control-treated GP developed typical acute, paralytic EAE 11 to 21 days after sensitization, whereas acute EAE was prevented in 33 of 49 8BE6-treated GP (67%), and the onset was delayed and disease progression was slowed in the others. Five GP treated with 8BE6 from days 11 to 14 after sensitization, at the onset of neurologic signs, rapidly deteriorated within hours after treatment and had loss of T cell staining, and lymphocytolysis in the CNS. 8BE6-treated GP which did not develop acute EAE were observed daily for up to 700 days (mean = 213 days). Twenty-nine of 39 (74%) had from one to six relapses or fixed neurologic deficits. GP in relapse were additionally treated with 8BE6 (22), MOPC-21 (5), or saline (6) in a cross-over protocol. Clinical scores were improved from days 2 to 12 after treatment (p less than 0.05), and complete recovery within 30 days occurred more frequently (p = 0.046) and more rapidly (p less than 0.01), after 8BE6 as compared with control treatments. Recoveries occurred more often if 8BE6 was given early in the relapse. Multiple treatments led to dose-dependent levels of serum antibodies to mouse immunoglobulin detected by an ELISA. There were no differences between acute and chronic EAE in numbers of inflammatory foci or numbers of macrophages and T cells in CNS infiltrates, but GP with chronic EAE had more extensive demyelination and vascular fibrosis and more numerous IgM+ B cells in parenchymal and meningeal infiltrates than in acute EAE (p less than 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)     

Involvement of host Fc receptors in antibody-mediated cutaneous basophil hypersensitivity reactions.

Cutaneous basophil hypersensitivity (CBH) reactions are heterogeneous delayed time course basophil-rich responses that can be mediated by either T cells, B cells, or serum antibodies. The current study examined the mechanism by which antibodies mediate CBH in guinea pigs. Fc competition experiments were constructed by passively transferring mixtures of anti-KLH serum and normal heterologous gamma-globulins. It was found that rabbit IgG and its isolated and purified Fc fragment [but not the (Fab')2 fragment] inhibited the ability of guinea pig immune serum to transfer CBH. Concurrent inhibition of transferred KLH-specific CBH and systemic passive cutaneous anaphylaxis (PCA) reactions by rabbit IgG or its Fc fragment, and not by sheep or bovine gamma-globulins, indicated that Fc receptors on cutaneous mast cells were probably involved in both CBH and PCA. It was also found that the basophil aspect of delayed cutaneous responses elicited by PHA was inhibited by Fc competition maneuvers. This could mean that some forms of apparently T cell-mediated CBH may be T cell dependent, but via secretion of molecules that bind to Fc receptors, as seems required in antibody-mediated CBH.     

IgE antibody-mediated cutaneous basophil hypersensitivity reactions in guinea pigs

Cutaneous basophil hypersensitivity (CBH) reactions are a heterogeneous group of delayed time course basophil-rich immune responses that can be mediated in the guinea pig by T cells, B cells, or IgG1 antibody. This study examined whether guinea pig IgE antibody could also mediate CBH reactions. IgE antibody to picryl or oxazolone determinants was induced by immunizing Hartley strain guinea pigs pretreated with cyclophosphamide. Hyperimmune serum from these animals was passed through a heavy chain-specific anti-IgG1 affinity column. The presence of IgE anti-hapten antibody in the filtrate fraction was verified by passive cutaneous anaphylaxis (PCA) testing with a 7-day period of local passive sensitization and by the heat lability (56 degrees C, 4 hr) of PCA activity. This IgE-rich fraction and the IgG1 fraction eluted from the column with base (0.2 M Na2CO3, pH 11.3) were transferred i.v. to separate groups of normal guinea pigs. Both fractions mediated delayed time course reactions that contained basophils. Macroscopic and microscopic reactions mediated by the IgE-rich fraction were abolished with heat (56 degrees C, 4 hr). Thus, two antigen-specific factors in guinea pig serum can mediate delayed time course basophil-containing reactions: IgG1 and IgE antibodies. IgE-mediated CBH reactions are similar to the late-phase reaction that follows IgE-dependent wheal-and-flare reactions in humans. The finding that guinea pig IgE can mediate a late reaction that contains basophils makes this a possible model for the human late-phase response, and suggests that some forms of CBH may play a role in human allergic disease.     

IgG1 antibody-dependent mediator release after passive systemic sensitization of basophils arriving at cutaneous basophil hypersensitivity reactions

When antigen is injected into a 24-hr cutaneous basophil hypersensitivity (CBH) reaction of an actively sensitized guinea pig, local basophils degranulate and release histamine. This reaction is called cutaneous basophil anaphylaxis and may be antibody mediated. We now report passive sensitization of basophils at CBH sites by systemic transfer of anti-picryl immune serum. Keyhole limpet hemocyanin- (KLH) immunized animals were skin tested with KLH to elicit 24-hr CBH reactions at day 7. Anti-picryl serum was injected i.v. at various times. On day 7, blue dye was injected i.v., and then 24-hr CBH sites vs nearby normal skin were challenged with 0.1 microgram picryl-human serum albumin (Pic-HSA). An immediate increase in vascular permeability (blueing) was noted at normal skin sites due to systemic passive cutaneous anaphylaxis (PCA), and augmented blueing occurred at CBH sites compared with normal skin. Systemic passive sensitization of CBH sites occurred when antiserum was administered as little as 1 hr before challenge of CBH site. However, local administration of anti-picryl serum (as in a local PCA reaction) was not able to sensitize tissue basophils, whether antigen was administered locally or systemically. The serum factor that mediated cutaneous basophil anaphylaxis was heat-stable (56 degrees C X 4 hr) 7S IgG1 antibody. Electron microscopy of Pic-HSA-challenged CBH sites in animals that received IgG1 antibody showed that local basophils undergo anaphylactic degranulation by exocytosis. These studies suggest that basophils arriving at CBH reactions are sensitized for anaphylactic function by antibody that can be acquired in the circulation, but possibly not at the local site.     

The inhibition of cutaneous basophil hypersensitivity reactions by a heterologous anti-guinea pig T cell serum.

Systemic treatment with a heterologous anti-T cell serum of guinea pigs immunized with EA in IFA markedly suppressed CBH reactivity to specific antigen and T cell mitogens, as judged by gross reactivity, histology, and skin histamine. The antiserum produced a marked drop in circulating lymphocytes, mainly at the expense of T cells, as indicated by the ability of surviving lymphocytes to rosette with rabbit RBC. It was postulated that the suppression of CBH reactivity is due to the depletion of T cells, which would have released a factor chemotactic for basophils. The data therefore provide further evidence that cutaneous reactions rich in basophils are primarily dependent on a population of T cells.     

Catecholamine- and endotoxin-influenced cutaneous basophil hypersensitivity in chickens.

1. Catecholamines suppress cutaneous basophil hypersensitivity (CBH) to intradermal phytohemagglutinin (PHA-P) challenge in chickens. 2. E. coli 0127:B8 endotoxin, reserpine, and propranolol prevented a norepinephrine-induced suppression of CBH. 3. PHA-P induced CBH appeared to be mediated through a beta-adrenergic receptor mechanism associated with plasma corticosterone in chickens.     

Systemic expression of cutaneous basophil hypersensitivity.

Guinea pigs primed for cutaneous basophil hypersensitivity (CBH) with several soluble proteins or with sheep erythrocytes developed a systemic, delayed-onset, maculopapular rash when challenged parenterally with specific antigen. The rash was most readily induced 5 to 7 days after immunization, at a time when local CBH skin test reactivity was also optimal. Miscroscopically, the rash resembled local CBH skin test reactions, being comprised of a papillary dermal infiltrate of basophils and lymphocytes and a striking dilatation and compaction of superficial venules. In addition to the systemic rash, animals expressing systemic CBH (SCBH) exhibited a striking eosinophilia at 24 hr which gave way to basophilia at 48 hr. Focal collections of eosinophils, and of smaller numbers of basophils, were found in the lungs and spleen; both eosinophils and basophils infiltrated the medulla of the thymus. Thus, basophil-rich infiltrations are favored in the skin even after systemic challenge with antigen and occur only to a much smaller extent in other organs where eosinophils may predominate. These differences in the response of various organs to challenge with parenteral antigen suggest that as yet unidentified local factors play a determinative role in regulating the inflammatory response. The pathogenesis of SCBH is not yet established, but it shares many of the properties of local CBH: histology, carrier specificity, development early after sensitization in the absence of detectable antibodies. Passive transfer has not been accomplished with serum alone but has been achieved irregularly with cells plus serum. SCBH may serve as a useful model for several disease states in man characterized by a systemic rash and eosinophilia, including certain types of drug reaction.     

Interactions of lectins and monoclonal antibodies with human mononuclear cells. I. Specific inhibition of OKT4 and OKT8 binding by Ricinus communis agglutinin and wheat germ agglutinin

We used flow cytometry to examine effects of lectins on interactions between human lymphocytes and the anti-T cell monoclonal reagents OKT4 (T helper-specific) and OKT8 (T suppressor-specific). Wheat germ agglutinin (WGA) inhibited OKT8 binding to lymphocytes by a mean 77% and Ricinus communis agglutinin (RCA-I) inhibited OKT4 binding by 66%. Inhibition was abolished in each case by appropriate carbohydrate hapten inhibitors of lectin binding, indicating it was mediated by the lectin saccharide combining sites. Neither WGA nor RCA-I inhibited binding of OKT3, a pan-T cell monoclonal reagent. In addition, a group of other lectins with a variety of nominal carbohydrate specificities did not inhibit OKT4 or OKT8 binding. Preincubation experiments and gel filtration indicated that inhibition in each case was due to competition between lectin and monoclonal for binding to cell surfaces, not to direct lectin-monoclonal antibody interactions. Treatment of lymphoid cells with OKT8 and complement reduced OKT8- and WGA-binding cells concurrently, whereas treatment with OKT4 and complement did not reduce percentages of either type of cell. Similarly, specific depletion of OKT8-binding cells abolished the mitogenic response to WGA but not that to PHA. Cell populations enriched for WGA-binding cells prepared by flow cytometry and cell sorting demonstrated parallel enrichment for OKT8-binding and depletion of OKT4-binding cells. Therefore, these data demonstrate specific inhibition of OKT4 and OKT8 binding by the lectins, RCA-I and WGA, respectively. Inhibition was mediated by lectin binding to lymphoid cell surfaces, perhaps directly to the T4 or T8 antigens. The observations indicate that lectins may prove useful for investigating structural features of some immunologic cell surface markers. Furthermore, they provide the possibility that certain in vitro effects of lectins on immune function may result from their interactions with molecules such as the T4 and T8 antigens.     

A newly described activity of guinea pig IgG1 antibodies: transfer of cutaneous basophil reactions.

Hapten-specific delayed time course skin reactions containing predominant accumulations of basophils and eosinophils were elicited in newborn guinea pigs after i.v. transfer of small amounts of oxazolone immune serum. The immune serum was fractionated by column chromatography procedures, and the fractions were examined for their ability in transferring this form of cutaneous basophil hypersensitivity (CBH). Only the 7S IgG-containing peak from Sephadex G-200 columns, and only the IgG1-containing fractions from DEAE columns, transferred CBH. An affinity column of bound oxazolone removed the activity from immune serum, and it could be recovered from the column by eluting with soluble oxazolone. About 35 microgram of purified IgG1 anti-oxazolone antibody could systemically transfer CBH reactivity. An immunoadsorbant column of anti-IgG1 removed this activity, but a column of anti-IgG2 did not. None of the procedures were able to separate activity in transferring CBH from passive cutaneous anaphylactic (PCA) activity classically associated with guinea pig IgG1 antibody. IgG1 from 8-day immune and 31-day hyperimmune donors were both effective. The average association constant of 8-day antibody was 8 X 10(-4) M-1. Transfer of cutaneous basophil reactions can be mediated by low affinity serum 7S IgG1 antibody.     

Effect of polysaccharides from Ganoderma applanatum on immune responses. I. Enhancing effect on the induction of delayed hypersensitivity in mice.

Prior intraperitoneal (i.p.) or oral administration of the polysaccharide preparation from a kind of mushroom, Ganoderma applanatum (Pers.) Pat. of Basidiomycetes, exerted an enhancing effect on the induction of delayed hypersensitivity (DH) to protein antigen as measured by the footpad reaction (FPR), and expanded the size of T cell memory for the IgG antibody response. One of the active principles was partially purified and found to be associated with a polysaccharide-rich fraction. The induction of DH was enhanced by treatment with an appropriate dose of the mushroom extract, whereas increasing the dose resulted in almost complete loss of the enhancing activity. The mechanism for the enhancing effect of the mushroom extract on the induction of DH was explored by the adoptive cell transfer technique. Although an i.p. injection of methylated bacterial α-amylase (M-BαA) in incomplete Freund's adjuvant (IFA) has been found to generate in the spleen the antigen-specific suppressor T cells capable of inhibiting the induction of DH 5 days after immunization, the same treatment of mice given prior injections of the mushroom extract did not raise the suppressor cell activity, but transfer of these spleen cells (6 × 10⁷) into syngeneic recipient mice which had been primed with a subcutaneous (s.c.) injection of M-BαA in complete Freund's adjuvant (CFA) resulted in substantial amplification of the expression of DH. The absence of effector T cells for DH in the transferred spleen cells was confirmed by the failure to transfer DH into cyclophosphamide (CY)-treated mice with the amplifying cells. The amplifying activity was antigen-nonspecific and mediated by cells sensitive to treatment with anti-θ antiserum plus complement. Therefore, the nonspecific enhancing effect of the mushroom extract could not be explained by the possibility that pretreatment with the extract eliminated the antigen-specific suppressor T cells. Other adoptive cell transfer experiments revealed that nylon wool-passed cells from mice unprimed but treated with the mushroom extract were able to exert an enhancing activity on the expression of effector T cells in DH. The results indicate that the treatment with an appropriate dose of the extract enhances the induction of DH by activation of the nonspecific amplifier T cells.     

Studies on delayed hypersensitivity to protein antigen. Antigen-specific suppression of delayed hypersensitivity by chemically modified antigen.

An extensively modified protein antigen (methylated bacterial α-amylase, M-BαA) which was neither reactive with anti-BαA antibody nor able to induce a humoral anti-BαA response, retained the ability to prime native BαA-specific T cells which were responsible for the enhanced anti-BαA response to subsequent immunization with BαA and delayed hypersensitivity (DH). The splenic T cell-rich fraction from mice primed with M-BαA collaborated with a native BαA-primed B cell-rich fraction to give a good adoptive IgG anti-BαA response in syngeneic irradiated mice, whereas M-BαA-primed B cell fractions failed to cooperate with native BαA-primed T cell fractions. Splenic T cells from mice given a subcutaneous (s.c.) injection of M-BαA in complete Freund's adjuvant (CFA) exhibited DH in syngeneic cyclophosphamide-treated mice. In the present study, native and methylated BαA were tested for their ability to generate suppressor T cells capable of inhibiting the development of DH. An intraperitoneal (i.p.) injection of either native or methylated BαA in incomplete Freund's adjuvant (IFA) interferred with the development of DH to M-BαA by an s.c. injection of the same antigen in CFA. Transfer of spleen cells from mice given an i.p. injection of either of these antigens 5 days previously, suppressed antigen-specifically induction and expression of DH in the syngeneic recipient mice. The suppressive activity was sensitive to treatment with anti-θ antiserum plus complement. These results indicate that the early phase of inhibition of DH after an i.p. injection is in part mediated by suppressor T cells and that M-BαA cross-reacts with native BαA at the suppressor T cell level as well as the level of effector T cells in DH.     

Membrane antigen phenotype of sensitized T lymphocytes mediating tuberculin-delayed hypersensitivity in rats

The membrane antigen phenotype of immune lymph node cells (LNC) which mediate tuberculin-delayed hypersensitivity (DH) in Lewis rats was examined. The results show that the T-cell population which expresses the RT7.1 alloantigen defined by the BC 84A monoclonal antibody contained cells capable of transferring DH. Separation of the RT7.1-positive T-cell population with the monoclonal antibodies W3/25, MRC OX-8, or DS 4.23 (which defines the RT6.1 alloantigen) revealed that either the W3/25-positive or the RT6.1-negative T-cell subpopulations contained DH effector cells, whereas the corresponding MRC OX-8-positive or RT6.1-positive T-cell subpopulations did not. Moreover, when the W3/25-positive T-cell subpopulation was divided into either RT6.1-positive or RT6.1-negative T-cell subsets, only the W3/25-positive, RT6.1-negative subset transferred DH. These results indicate that the effector cells that mediate tuberculin DH are contained within the immune T-cell subset which bears both the RT7.1 and the W3/25 markers, but lacks both the MRC OX-8 and the RT6.1 markers.     

T cell surface markers expression by immature human thymocytes in in vitro culture: role of Ia+ accessory cells

Previous studies have indicated that the human thymus is composed of several discrete compartments. Cortical thymocytes are reactive with the monoclonal antibody anti-T6, whereas most medullary cells, unreactive with anti-T6, stain brightly with anti-T3 antibody, which defines mature T cell populations. By using an indirect immune rosette method, we isolated the minor thymocyte population (1 to 2% of all thymocytes) lacking both T3 and T6 but expressing T11 antigens. These cells could be maintained in culture supplemented with recombinant IL 2 (Rec-IL 2) for several days. Under these conditions, T3-T6- cells were shown to undergo phenotypic changes. In the absence of thymic macrophage (Mo), T3+ and T8+ thymocytes appeared in culture, whereas the development of T4+ cells strictly required the presence of Mo. The expression of T4 antigen could be largely prevented by the addition of anti-HLA-DR antibody, further indicating that Ia+ accessory cells had the ability to promote in vitro development of T4+ thymocytes. In the presence of Mo, not only T4+ but also T8+ cells were obtained. Double fluorescence staining with anti-T8-FITC and anti-T4-biotin demonstrated that after 12 days of culture, T4 and T8 antigens were mutually exclusive. Furthermore, during the course of these studies, we observed that under the culture conditions utilized (e.g., presence or absence of Mo), T3-T6-thymocytes failed to express the T6 antigen. Thus, the in vitro development of T cells bearing a mature phenotype could be obtained in the absence of intermediate expression of cortical (T6+) thymocytes.     

Sensitization of circulating basophils in guinea pig recipients of passive transfer of cutaneous basophil hypersensitivity (CBH) with immune serum: antigen-specific histamine release in vitro

An in vitro histamine release assay was used to test the hypothesis that passive sensitization of circulating basophils is associated with the activity of immune serum that transfer the ability to elicit cutaneous basophil hypersensitivity (CBH) reactions. Systemic i.v. transfer of several types of immune sera that mediate CBH also led to passive sensitization of circulating basophils for antigen-specific release of histamine in vitro. In addition, we found that immune serum passively sensitizes basophils in vitro. Thus immune sera had three activities that are probably interconnected: sera will 1) passively transfer CBH in vivo, 2) passively sensitize basophils in vivo, and 3) passively sensitize basophils in vitro. These results suggest that passive sensitization of circulating basophils by immune serum contributes to the mechanism by which antibodies transfer the ability to elicit CBH reactions.     

Antibody enhances lymphocyte proliferation in guinea pigs immunized to express cutaneous basophil hypersensitivity

Lymphocytes from HSA-sensitized guinea pigs expressing cutaneous basophil hypersensitivity (CBH) proliferate in the presence of specific antigen. We report that this proliferative response is enhanced by the addition of anti-HSA antibody, either in the form of whole immune serum or as purified antibody. The enhancement was characterized as a marked shift of the antigen dose-response curve such that significant [3H]thymidine incorporation was observed at antigen concentrations much lower than those eliciting a comparable response in the absence of immune serum. Enhancement was antigen specific and required an intact immunoglobulin molecule. Antibodies capable of enhancing antigen-specific lymphocyte proliferation could be isolated from serum by affinity chromatography as early as 7 days after sensitization and were also evident in sera obtained at later intervals. It is unlikely that such antibodies account for the progressive decline of CBH reactivity and they may actually influence its initial expression.     

Treatment of murine lupus with monoclonal anti-T cell antibody

Three strains of autoimmune mice (MRL/lpr, NZB/NZW, and BXSB) were treated with repeated injections of rat monoclonal anti-T cell antibody (anti-Thy-1.2) in order to determine 1) the extent and duration of target cell depletion, 2) the effect of T cell depletion on the course of autoimmunity, and 3) the magnitude and consequences of the host immune response to the monoclonal antibody. Mice were treated with 6 mg of anti-Thy-1.2 every 2 wk beginning early in their disease. Treatment produced a substantial reduction in circulating T cells in all three strains. Therapy was beneficial in MRL/lpr mice. It reduced lymphadenopathy, lowered autoantibody concentrations, retarded renal disease, and prolonged life. In contrast, treatment did not improve autoimmunity in NZB/NZW mice, and it caused fatal anaphylaxis in BXSB mice. These findings demonstrate that monoclonal antilymphocyte antibodies can serve as specific probes to examine the cells that contribute to autoimmunity. Moreover, they illustrate the potential therapeutic value of monoclonal antilymphocyte antibodies when a pathogeneic cell subset can be identified. However, the same antibody may have a broad range of effects, from efficacy to severe toxicity, even in diseases that share clinical features.     

Specific lysis of human tumor cells by T cells coated with anti-T3 cross-linked to anti-tumor antibody

Heteroaggregates containing anti-T3 cross-linked to anti-target cell antibodies have been shown to cause human T cells to lyse target cells that express antigens recognized by the anti-target cell antibody. In this study, we test targeted human T cells for the ability to lyse human tumor cells as a first step toward the application of this phenomenon to tumor immunotherapy. Several monoclonal anti-human tumor antibodies were assayed for binding to a number of human tumor lines and for the ability to promote specific tumor cell lysis when cross-linked with anti-T3. We found that anti-T3 cross-linked to anti-tumor monoclonal antibodies caused cloned human T cells and fresh peripheral blood T cells to lyse the tumor cells with the same specificity as predicted by the binding studies. Peripheral blood T cells were then tested in the presence of various heteroaggregates for the ability to lyse single cell suspensions prepared from fresh tumor or fresh normal tissue. These studies showed that heteroaggregates containing anti-T3 cross-linked to anti-tumor antibody cause fresh human T cells to specifically lyse fresh tumor cells, but not (with one exception) fresh normal cells.     

Signaling from LFA-1 contributes signal transduction through CD2 alternative pathway in T cell activation.

LFA-1, a member of the integrin family of molecules, is involved in mediating cellular adhesion in all phases of the immune response, playing a role in the interaction of helper T cells as well as in killing of target cells by both cytotoxic T cells and natural killer cells. We have developed a monoclonal antibody, anti-HVS6B6, which recognizes a functionally unique epitope of the LFA-1 molecule. Although this mAb itself was not mitogenic against T cells, it induced a strong proliferative response when added to T cells with submitogenic concentrations of anti-CD2 (anti-T11(2) and anti-T11(3)) mAbs. In contrast, other anti-LFA-1 mAbs (CD11a and CD18) suppressed this anti-CD2 mAb-induced T cell proliferation. Kinetic studies showed that anti-HVS6B6 acts on an early event in CD2-mediated T cell activation. Although T11(3)-epitope expression induced by anti-T11(2) mAb was not affected by treatment of cells with anti-HVS6B6, both Ca2+ influx and phosphatidylinositol turnover induced by anti-CD2 mAbs were markedly enhanced by the pretreatment of T cells with anti-HVS6B6 mAb. These results indicate that the LFA-1 mediating signal contributes to a very early phase of signal transduction during CD2-mediated T cell activation.     

Characterization of a localized basophil hypersensitivity lesion in guinea pig conjunctiva

Basophils accumulate in response to antigen challenge in cutaneous basophil hypersensitivity (CBH) reactions. Two ocular diseases, vernal conjunctivitis and contact-lens-associated conjunctivitis, are also characterized by this histopathology. We have refined a model previously developed in guinea pig conjunctiva by precisely defining the site of antigen injection and correlating the site with the clinical and histologic changes. Guinea pigs were primed by an intradermal injection of keyhole limpet hemocyanin (KLH) in the flank and challenged (Day 6) by injection of a small bolus of KLH just under the conjunctival epithelium. Twenty-four hours later histologic examination showed a perivascular infiltrate of inflammatory cells containing large numbers of basophils. Eosinophils, neutrophils, macrophages, and mast cells were also seen. Serial sections of the reaction site showed discrete boundaries. At all sites examined in antigen-challenged tissues, there were significantly more basophils than in control-injected conjunctiva. Insertion of a sterile needle or injection of PBS or KLH into normal conjunctiva induced a significant increase in neutrophils and some macrophages. Injection of graded doses of antigen into the conjunctiva of primed animals, resulted in a dose-dependent increase in basophils up to 50 micrograms KLH (optimal dose).