Enhancement of human blood eosinophil cytotoxicity by semi-purified eosinophil colony-stimulating factor(s)

Purified human blood eosinophils, when incubated in human placental conditioned medium (a source of colony-stimulating factors) [CSF]) demonstrate an enhanced ability to damage antibody- or complement-coated schistosomula. This enhancement represents a 4- to 10-fold increase of eosinophil schistosomicidal ability and a 10-fold lowering of the threshold for antibody or complement required in the killing reaction. The activity that enhances eosinophil cytotoxicity and the eosinophil colony-stimulating activity in the placental conditioned medium are eluted in the same fraction (CSF-alpha) after chromatography on Sephadex G-100 and phenyl-Sepharose columns, suggesting that these two activities might be associated with the same molecule. CSF-alpha enhances the adherence step of the killing reaction: antibody-coated larvae were frequently found covered by several layers of eosinophils in tubes containing CSF-alpha. Such a degree of adherence was rarely seen in control tubes lacking CSF-alpha. This enhancement of the eosinophil adherence is detectable 45-60 min after addition of CSF-alpha to the culture. It is not affected by washing the cells after a short time of preincubation with CSF-alpha, and it occurs in the absence of protein synthesis, whereas colony-stimulating activity requires continuous protein synthesis and ceases when CSF is removed from the culture. Finally, CSF-alpha enhances the temperature-dependent reaction that insures the irreversibility of eosinophil attachment to schistosomula. These observations suggest that eosinopoietic factors could be responsible for some of the modified properties of blood eosinophils in eosinophilic individuals.

Genetic control of eosinophilia in mice: gene(s) expressed in bone marrow-derived cells control high responsiveness

A heterogeneity in the capacity of strains of mice to mount eosinophilia is described. BALB/c and C3H are eosinophil high responder strains (EO-HR) and CBA and A/J are eosinophil low responder strains (EO-LR), judged by the response of blood eosinophils to Ascaris suum, and the response of blood, bone marrow, and spleen eosinophils to keyhole limpet hemocyanin given 2 days after 150 mg/kg cyclophosphamide. Some of the gene(s) for high responsiveness appear to be dominant because (EO-HR X EO-LR)F1 mice were intermediate to high responders. This gene is expressed in bone marrow-derived cells because radiation chimeras of the type EO-HR leads to F1 were high responders and EO-LR leads to F1 were low responders. This description of a genetic control of eosinophilia in mice may be useful in understanding the role of this cell in parasite immunity and allergy.

Genetic control of eosinophilia in mice: gene(s) expressed in bone marrow-derived cells control high responsiveness

A heterogeneity in the capacity of strains of mice to mount eosinophilia is described. BALB/c and C3H are eosinophil high responder strains (EO-HR) and CBA and A/J are eosinophil low responder strains (EO-LR), judged by the response of blood eosinophils to Ascaris suum, and the response of blood, bone marrow, and spleen eosinophils to keyhole limpet hemocyanin given 2 days after 150 mg/kg cyclophosphamide. Some of the gene(s) for high responsiveness appear to be dominant because (EO-HR X EO-LR)F1 mice were intermediate to high responders. This gene is expressed in bone marrow-derived cells because radiation chimeras of the type EO-HR leads to F1 were high responders and EO-LR leads to F1 were low responders. This description of a genetic control of eosinophilia in mice may be useful in understanding the role of this cell in parasite immunity and allergy.

Cyclophosphamide pretreatment induces eosinophilia to nonparasite antigens

Eosinophilia is usually regarded as a T cell-dependent hemopoietic response, although in most instances of immune responses by T cells there is no accompanying eosinophilia. BALB/c mice immunized with keyhole limpet hemocyanin (KLH) in complete Freund's adjuvant (CFA) were found not to develop eosinophilia, whereas pretreatment of such mice with 150 mg/kg cyclophosphamide (CY) induced marked eosinophilia in the blood (1000 to 3000/mm3) and bone marrow. CY as well as CY and KLH in CFA cause a leukocytosis and neutrophilia, but significant eosinophilia was seen only in mice receiving both CY and KLH-CFA. The eosinophilic response depended on the dose of CY and peaked 13 days after immunization, and was preceded by a bone marrow eosinophilia that peaked 8 days after immunization. No eosinophilia occurred in BALB/c nu/nu mice after CY and KLH-CFA but did occur in the nu/+ littermates. This model in mice of eosinophilia in response to CY followed by a nonparasite antigen should be useful in the analysis of T cell signals that might regulate eosinophilia.

Cyclophosphamide pretreatment induces eosinophilia to nonparasite antigens

Eosinophilia is usually regarded as a T cell-dependent hemopoietic response, although in most instances of immune responses by T cells there is no accompanying eosinophilia. BALB/c mice immunized with keyhole limpet hemocyanin (KLH) in complete Freund's adjuvant (CFA) were found not to develop eosinophilia, whereas pretreatment of such mice with 150 mg/kg cyclophosphamide (CY) induced marked eosinophilia in the blood (1000 to 3000/mm3) and bone marrow. CY as well as CY and KLH in CFA cause a leukocytosis and neutrophilia, but significant eosinophilia was seen only in mice receiving both CY and KLH-CFA. The eosinophilic response depended on the dose of CY and peaked 13 days after immunization, and was preceded by a bone marrow eosinophilia that peaked 8 days after immunization. No eosinophilia occurred in BALB/c nu/nu mice after CY and KLH-CFA but did occur in the nu/+ littermates. This model in mice of eosinophilia in response to CY followed by a nonparasite antigen should be useful in the analysis of T cell signals that might regulate eosinophilia.

An autoantibody reactive with nuclei of polymorphonuclear neutrophils: a cell differentiation marker

An autoantibody that reacted with nuclei of polymorphonuclear neutrophils (PMN) was detected at titers of greater than 10 in sera of 25 of 50 patients with rheumatoid arthritis and 36 of 50 with autoimmune chronic active hepatitis but in none of 160 controls comprising 24 patients with alcoholic cirrhosis, 36 with multiple myeloma, and 100 healthy subjects. Through the use of enriched populations of hemopoietic cells, this antibody was shown to be cell-specific, reacting only with the nucleus of the mature neutrophil. It was unreactive with nuclei of progenitor cells in the myeloid series and with nuclei of eosinophils, monocytes, lymphocytes, and thymocytes. It reacted with a determinant that appeared to be a differentiation antigen. This cell-specific autoantibody may prove to be of value in analytical studies of granulocyte maturation.

Immune evasion by Schistosoma mansoni: loss of susceptibility to antibody or complement-dependent eosinophil attack by schistosomula cultured in medium free of macromolecules

Schistosomula of Schistosoma mansoni, recovered either after penetration of cercariae through isolated rat skin or by mechanical transformation of cercariae, become fully resistant after 24-48 h of culture to damage by human blood eosinophils in the presence of human anti-schistosomular sera. Cultured schistosomula are also shown to lose their susceptibility to attack by human eosinophils in the presence of human complement. This resistance is related to the simultaneous reduction of the ability of human anti-schistosomular antibodies and human complement component C3 to bind to the surface of the cultured larvae. The development of insusceptibility to antibody, complement and eosinophil-mediated attack does not require the acquisition by the schistosomula of a protective coat of host or other macromolecules, since it is achieved in chemically defined culture medium free of serum and macromolecules. This supports the hypothesis that schistosomula undergo intrinsic changes which render them insusceptible to immune attack.

Parasite immunity and the major histocompatibility complex

Parasite infestations offer fertile ground for investigation of the relationship between immunity, disease and the major histocompatibility complex (MHC). However, due to the complexities of parasite life cycles and the success of parasites in evading the immune response, immune reactions against the parasite often do not parallel protective immunity, and immunity does not imply lack of disease. -- An additional level of complexity is introduced in some forms of parasite immunity by accessory effector cells, e.g., macrophages and eosinophils, that need to be 'activated' for maximal effectiveness, and the 'activated' form of these cells may partly compensate for a deficiency in specific immune responses. -- It is not surprising, therefore, that polygenic effects operate in parasite immunity and reports linking non-MHC genes with parasite immunity far out number those linking MHC genes with it. From the reports that do link MHC genes with parasite immunity, two areas emerge that are interesting. First, the increased incidence of certain HLA genes in people with schistosomiasis who develop hepatosplenic disease may pinpoint individuals at risk of morbidity and direct early treatment to them. Second, mechanisms that intimately involve MHC products but are not linked to a particular MHC haplotype, may indicate newer areas in the investigation of parasite immunity.

Enhanced helminthotoxic capacity of eosinophils from patients with eosinophilia

To determine whether eosinophils from patients with eosinophilia have an enhanced capacity to kill parasites, we compared purified eosinophils (mean purity, 89 per cent) from 30 patients with various degrees of eosinophilia and with or without infection with Schistosoma mansoni for the capacity to kill schistosomula, the larval stage of S. mansoni, in vitro. There was a significant correlation between peripheral eosinophil count and antibody-dependent, eosinophil-mediated death of parasites after 40 hours of culture (P < 0.0001). Antibody-dependent adherence of eosinophils, measured after two hours of incubation, also correlated with the capacity of the eosinophils to kill the parasites. The correlation between the killing capacity of eosinophils and their peripheral-blood count was observed in patients both with and without S. mansoni infection. We suggest that eosinophilia involves not only a quantitative change in eosinophil numbers but also a qualitative change in functional capacity that renders circulating eosinophils more effective in resisting parasitic infections.

Mechanism of the interaction mediating killing of Schistosoma mansoni by human eosinophils

Recent work on the role of eosinophils in immunity to Schistosoma mansoni is summarized. In vitro studies have shown that human eosinophils can kill antibody-covered schistosomula. The killing mediated by eosinophils is associated with adherence of these cells and subsequent degranulation and release of eosinophil major basic protein onto the larvae. The major basic protein itself can kill the larvae. Antibody-dependent eosinophil adherence to the larvae proceeds in at least two distinct steps. The first is mediated by Fc receptors and is relatively weak; the second is a temperature-dependent step which allows a firm irreversible binding of eosinophils to schistosomula. This stable binding is associated with degranulation of eosinophils, a process which appears to contribute to the preferential capacity of this cell to mediate antibody-dependent damage to schistosomula.

Functional studies on purified eosinophils and neutrophils from patients with Schistosoma mansoni infections

Unpurified peripheral blood leucocytes or purified eosinophils and neutrophils from patients with schistosomiasis and from normal individuals were compared for their ability to interact with antibody coated schistosomula of Schistosoma mansoni. There was no difference in the ability of buffy coat cells or neutrophils from patients and from normal individuals to mediate antibody-dependent 51Cr release from labelled schistosomula. However, eosinophils from patients were significantly better than those from normal individuals in causing antibody-dependent 51Cr release. This enhanced activity of eosinophils from patients with schistosomiasis was found to correlate with the intensity of their infection as judged by faecal egg counts. Eosinophils from patients also contained a higher proportion of cells with detectable Fc receptors than those from normal individuals. It is suggested that the difference in the behaviour of eosinophils from patients and from normals may reflect an 'activated' state of these cells in the infected individuals.

Interactions between human eosinophils and schistosomula of Schistosoma mansoni. II. The mechanism of irreversible eosinophil adherence

Previous work (1)(1) has shown that normal human eosinophils show a preferential capacity, in comparison with neutrophils, to bind to antibody- coated schistosomula of Schistosoma mansoni. This effect is attributable to a temperature-dependent function of the eosinophil which renders its binding stable and irreversible by aggregated gamma globulin or Staphylococcus aureus protein A. In contrast, the binding of neutrophils is readily reversible by these agents. It has now been shown that the differences observed between eosinophils and neutrophils is a property of their interaction with living schistosomula. When dead or artificially damaged schistosomula were tested, neutrophils showed a markedly enhanced capacity to adhere, in both the presence and absence of anti-chistosomular serum. Subsequent experiments were designed to test the hypothesis that the strong, stable binding of eosinophils was attributable to degranulation, with release of granule contents which would then serve as ligands to bind the cell to the organism. First, an enhanced adherence both of eosinophils and of neutrophils could be demonstrated in the presence of eosinophil major basic protein (MBP) or of protamine, a high molecular weight cation. Second, the binding of eosinophils induced by concanavalin A (Con A) was found to differ markedly from that induced by antischistosomular serum. Con A-mediated binding of eosinophils was fully reversible by alpha-methyl-mannoside, was not associated with damage to the organism, and did not lead to degranulation of the cell, as estimated by measuring the release of MBP into the culture supernate. However, induction of degranulation of concanavalin A-bound eosinophils, but not of neutrophils, with the calcium ionophore A23187 converted the reaction into one which was no longer reversible by alpha- methylmannoside and in which damage to the organism now did occur. These findings support the hypothesis that the stable binding of eosinophils is associated with degranulation, a process which may contribute to the preferential capacity of this cell to mediate antibody-dependent damage to schistosomula.

A new method for the purification of human eosinophils and neutrophils, and a comparison of the ability of these cells to damage schistosomula of Schistosoma mansoni

Centrifugation of human white blood cells over either Ficoll-Hypaque or slightly hypertonic Metrizamide discontinuous gradients reliably produces separate fractions that are enriched for either neutrophilic or eosinophilic granulocytes. This single step purification routinely yields 90 to 100% pure neutrophils and 85 to 100% pure eosinophils. Metrizamide gradients, in particular, reproducibly provide high yields of 90 to 100% pure eosinophils from normal subjects with 2 to 3% eosinophils in their peripheral blood. The method does not damage cells as judged by morphologic or functional criteria. The purified cell populations were tested for their ability to damage antibody-coated schistosomula either by the measurement of 51Cr release from labeled organisms, or by direct morphologic assessment. Neutrophils were superior in their ability to release 51Cr from labeled organisms, but eosinophils adhered to the organisms to a greater extent and induced microscopically detectable damage.

Major histocompatibility complex products restrict the adherence of cytolytic T lymphocytes to minor histocompatibility antigens or to trinitrophenyl determinants on schistosomula of Schistosoma mansoni

We have previously shown that schistosomula passaged through mice acquire histocompatibility (H) antigens that can be recognized either by alloantibody or by alloreactive cytolytic T lymphocytes (CTL). The latter specifically adhere to but fail to damage the parasite. In this paper we describe the use of trinitrophenyl (TNP)-labeled schistosomula to show that the adherence of CTL with specificity for TNP-modified syngeneic cells is restricted by the major histocompatibility complex (MHC) in a fashion similar to that seen in the lysis of TNP-labeled tumor targets. Thus, these CTL adhere only to schistosomula that have both the appropriate H antigens and TNP determinants on their surface, and not to schistosomula bearing either of these antigens by themselves. We note a significant degree of adherence to schistosomula bearing TNP determinants and H antigens allogeneic to the CTL. Anti-minor H antigen CTL are also restricted by the MHC in their adherence; thus, they only adhere to schistosomula that carry both the major and minor H antigens of the stimulator cells. These antigens can be acquired either by a single passage in vivo of schistosomula through congenic strains that possess both the relevant antigens or by sequential passage through two different strains, each contributing one of the antigens in question.

Acquisition of murine major histocompatibility complex gene products by schistosomula of Schistosoma mansoni

Schistosoma mansoni schistosomula recovered from the lungs of inbred mice were shown to possess serologically detectable alloantigens on their tegumental surfaces. Using appropriate antisera and infected congenic and recombinant mice as worm donors, gene products of the K and I subregions of the major histocompatibility complex were demonstrated among these alloantigens acquired by the parasites. In contrast, other cell surface alloantigens, such as Thy 1, Ly 1, and H-Y and the serum proteins albumin, C3 and Ig, could not be detected on the surface of lung schistosomula by means of comparable techniques. In another series of experiments, schistosomula recovered from the lungs of mice and reinjected into allogeneic recipients were shown to exchange their alloantigens during an 87-h period of examination. Similarly, lung schistosomula cocultured with allogeneic lymphocytes were shown to acquire major histocompatibility complex (MHC) coded antigens from the cells. It is possible that as acquired host molecules, MHC gene products may disguise the surface of schistosome parasites thereby rendering them insusceptible to immune attack.

Histocompatibility linked immune responsiveness and restrictions imposed on sensitized lymphocytes

Delayed-type hypersensitivity (DTH) transfer to GAT was restricted by the I-A region of the major histocompatibility complex (MHC). Sensitized cells from F1 hybrid mice between responder and nonresponder strains transferred DTH to syngeneic F1 mice and to naive parental strain recipients of the responder but not of the nonresponder haplotypes. These results are interpreted to favor the postulate that the MHC-linked Ir genes exert their effects by coding for components which allow interactions between particular I region gene products and the region to form stable structures immunogenic for DTH T cells.