Production and characterization of monoclonal antibodies to guinea pig lymphoid differentiation antigens

Common cell-surface antigens functioning in self-recognition reactions by both somatic cells and gametes in the solitary ascidian Halocynthia roretzi

The "contact reaction" is an extremely rapid allogeneic cytotoxic reaction (ACR) mediated by hemocytes in the solitary ascidian Halocynthia roretzi. It has been proposed that regulation of the alloreactivity of hemocytes may be involved in preference for fertilization or self-sterility in this species. To identify the receptors and target ligands involved both in self-recognition by somatic cells and self-discrimination by gametes, we produced monoclonal antibodies (mAbs) that inhibit the ACR mediated by hemocytes and tested their effects on fertilization. Six different mAbs that inhibit the ACR were prepared and categorized into three groups. Although all three mAbs seemed to have the same ability to inhibit the ACR, almost constant and statistically significant inhibition (CRB1.1) and infrequent but significant inhibition (CRB2.1, and CRB3.1) of the ACR were observed in the same pairs of animals. Pretreatment of the unfertilized eggs with CRB1.1, CRB2.1, and CRB3.1, resulted in the constant and statistically significant inhibition, infrequent but significant inhibition, and no inhibition, respectively, of fertilization. Antigens recognized by CRB1.1 (CRB1.1 antigens) were detected on the cell surface of all types of hemocytes and on the vitelline coat and follicle cells of unfertilized eggs. CRB2.1 and CRB3.1 antigens were detected on the surface of certain types of hemocytes and follicle cells, but not on the vitelline coat. CRB mAbs were directed against different epitopes in the N-linked glycan on glycoproteins. These common carbohydrate antigens on somatic cells and gametes may function in some recognition processes in ACR and fertilization in H. roretzi.

Immune abnormalities in guinea pigs with asymptomatic congenital syphilis

Spleens from 1-20-wk-old guinea pigs infected in utero with Treponema pallidum and age-matched controls, born to normal and heat-killed (56 degrees C, 2 h.) T. pallidum-injected mothers, were examined for their in vitro lymphoproliferative response to phytohemagglutinin, concanavalin A, and lipopolysaccharide. Additionally, T cell surface markers (mu-chain, pan T, CD4, and CD8) were determined in spleen, lymph node, and peripheral blood from 10-wk infected and normal pups by single and dual parameter fluorescence-activated cell sorter analysis. Compared with control animals, congenitally infected animals showed a remarkable prolonged naive-type of immune response as reflected by the higher (p < 0.01) proliferative responses to both T cell mitogens (up to 20 wk of age), and the weaker response to the B cell mitogen, significantly different (p < 0.01) at 10 wk of age. As opposed to controls, in all organs examined the level of CD8+ (cytotoxic/suppressor) T cells was significantly diminished (p < 0.01); consequently, the CD4/CD8 ratio was significantly elevated (p < 0.05). The role of C4 complement component and the nature and potential role of the immature T and B lymphocyte responses in asymptomatic congenital syphilis is discussed.

CD5+ and CD5- B1-like lymphocytes in healthy guinea pig

Spleen, lymph node, and peripheral blood lymphocytes from healthy guinea pigs (gp) were examined for their ability to produce polyreactive autoantibodies to a battery of self-antigens and to cryptic determinants (phosphatidylcholine) on bromelain-treated mouse red blood cells (Br-MRBC). The mouse monoclonal antibody (Mab) 8BE6 anti-gp pan-T (CD5) marker was used for identification of CD5+ B1 cells by the plaque-forming assay (PFC), immunofluorescence, complement-mediated cytotoxicity, and immunocytochemistry. The detection of CD5+ cells by the 8BE6 Mab depended on the method used. They were better demonstrated by cytolysis and immunocytochemistry than by FACS analysis. By the latter method, the level of the CD5+ B cell subpopulation was associated neither with the age of the gp nor with the organ examined. Similarly wide ranges of PFC were detected in untreated or LPS-treated animals regardless of age and organ. The vast majority of the LPS-stimulated IgM antibody-secreting B lymphocytes reacting with the Br-MRBC, and those producing natural autoantibodies, did not bind the 8BE6 Mab.

Passive immunization protects guinea pigs from lethal Toxoplasma infection

The cellular and humoral interactions that contribute to protective immunity in toxoplasmosis were studied by adoptive transfer of selective cell populations or immune serum and its fractions into normal syngeneic strain 2 guinea pigs. The results of this study with the RH strain of Toxoplasma gondii confirm and extend the findings of previous studies by showing that the passive transfer of parasite-sensitized T cells or of immune serum from previously infected donors protected recipient guinea pigs against lethal toxoplasmosis. An additional key finding was that similar levels of complete protection against lethal infection occurred in guinea pigs receiving partially purified anti-Toxoplasma immunoglobulins or immune cells that had been enriched for B cells prior to transfer. Cells residing in the spleen, lymph nodes and peritoneal cavity, but not the thymus, were equally effective in conferring immunity to challenged recipients. In addition, cell titration experiments revealed that guinea pigs could survive T. gondii infection by infusing them with as little as 2 x 10(7) sensitized T cells or B cells. Unlike protection mediated by T cells, protection against lethal disease occurring in the B cell recipients was associated with the formation of Toxoplasma antibodies. These findings illustrate the major role of both humoral and cell-mediated immunity in affording protection against toxoplasmosis based on a guinea pig model of the human disease.

Experimental murine hypersensitivity pneumonitis

To establish a model of experimental hypersensitivity pneumonitis (EHP) in mice and to examine the influence of genetic background on the pulmonary inflammatory response to Micropolyspora faeni, we determined the responses of C57BL/6, SJL/J, and C3H/HeJ mice to intratracheal (i.t.) injections of M. faeni. Recipient animals received lymph node cells (LNC), peritoneal exudate cells (PEC), and spleen cells (SC) from sensitized mice cultured in vitro with M. faeni. Controls included serum containing anti-M. faeni antibody; uncultured SC from M. faeni-sensitized donors, and M. faeni-cultured SC from ovalbumin (OA)-sensitized donors. Recipients were challenged i.t. with M. faeni or normal saline 48 hr after the cell or serum transfer. We developed a model of EHP in mice. Increasing amounts of i.t. M. faeni were associated with increasing extent of pulmonary inflammation with no difference between the mouse strains. There was substantial increase of the extent of pulmonary abnormalities in the animals receiving cultured SC. The number of transferred cells and the M. faeni concentration correlated with the extent of pulmonary histologic abnormalities. Cultured PEC and LNC could transfer EHP in C3H/HeJ mice only. Serum containing anti-M. faeni antibody, cultured SC from OA-sensitized donors, and noncultured SC from sensitized donors could not transfer EHP. We conclude that it is possible to adoptively transfer EHP.

Experimental hypersensitivity pneumonitis: suppressor cell influences

Experimental hypersensitivity pneumonitis (EHP) can be transferred to strain 2 guinea pigs by lymph node cells (LNC) cultured in vitro with antigen. Using mixtures of cell populations, we sought to determine if functional suppressor cells were present in our system. We also characterized the composition of cell populations that were capable (blast 10 micrograms/mL Micropolyspora faeni from 2-week donor animals) and incapable (blast 0 micrograms/mL M. faeni from 2-week donor animals; blast 10 micrograms/mL from 8-week donor animals) using flow cytometry, anti-Ig and monoclonal antibody 8BE6 (T cell marker) of transferring EHP. Two groups of donors were used: animals sensitized with Freund's adjuvant and M. faeni and challenged with either two or eight weekly intratracheal (IT) injections of M. faeni (2- and 8-week groups). LNC from donor animals were cultured with a soluble extract of M. faeni (10 or 0 micrograms/mL) blasts isolated and transferred IV to syngeneic recipients. Control animals received media IV. Recipients were challenged IT with M. faeni 48 h after the cell transfer and sacrificed 4 days thereafter. All animals were maintained in HEPA filtered air. Randomly selected microscopic fields of the lung (250/animal) were judged to be normal or abnormal without knowledge of treatment. There was a low level of pulmonary response to an IT challenge of M. faeni in media recipients. There was a substantial increase (P less than .01) in pulmonary abnormalities in the animals receiving blasts from the 10-micrograms/mL M. faeni 2-week group. Addition of cells from incompetent cell populations (0 micrograms/mL M. faeni 2-week donors or 10 micrograms/mL M. faeni 8-week donors) did not alter the ability of competent populations to transfer EHP. Cells cultured with antigen had a decreased proportion of T cells and an increased proportion of SIg+ and large cells. Competent and incompetent cell populations did not differ in regard to proportion of large cells, surface Ig+, or T cells. We conclude that the inability of certain cell populations to transfer EHP is not associated with the appearance of functional suppressor cells. Differences of ability to transfer EHP do not correlate with differences of size distribution or T and B cell composition.

Erythrocyte receptor (CD2)-bearing T lymphocytes are affected by diet in experimental pulmonary tuberculosis

Outbred (Hartley) and inbred (strain 2 and 13) guinea pigs were vaccinated with Mycobacterium bovis BCG and placed on isocaloric, purified diets containing either 10 or 30% ovalbumin or on commercial guinea pig chow. Six weeks later, the animals were challenged by the respiratory route with virulent M. tuberculosis H37Rv. At intervals postchallenge, groups were tuberculin tested and sacrificed. Thymus-dependent (T) lymphocytes were enumerated either by rosette formation with rabbit erythrocytes or by the indirect immunofluorescence assay (IFA) with a guinea pig pan-T-cell monoclonal antibody, 8BE6. Protein-deficient guinea pigs of all three strains had significantly fewer erythrocyte rosette-forming (CD2+) T cells in the peripheral blood, and malnourished strain 2 and Hartley guinea pigs exhibited reduced levels of CD2+ T cells in the thymus. In contrast, animals of all three strains fed the low-protein diet harbored more CD2+ T cells in the bronchotracheal lymph nodes than did their control-fed counterparts. A larger proportion of lymphocytes from the blood and lymph nodes of all three strains were IFA positive than formed erythrocyte rosettes regardless of diet treatment. Diet had no effect on IFA-positive lymphocytes in those organs. Protein deficiency is associated with significant alterations in the number and/or distribution of T lymphocytes expressing functional CD2-receptors in BCG-vaccinated animals exposed to virulent mycobacteria by the pulmonary route. These alterations may contribute to the reduction in BCG vaccine efficacy observed in this model.

Macrophage-activating T-cell factor(s) produced in an early phase of Legionella pneumophila infection in guinea pigs

Protective immunity of guinea pigs against Legionella pneumophila was studied by infecting the animals with a sublethal dose (about 2 x 10(4) CFU) of the organism. The bacteria multiplied in the liver, spleen, and lungs up to day 4 after the intraperitoneal infection. The live bacteria in these organs decreased quickly thereafter and were eliminated by day 7. A delayed-type skin reaction and lymphoproliferation of spleen cells to Formalin-killed L. pneumophila were detected from days 5 and 6, respectively, after infection. Peritoneal macrophages obtained from guinea pigs infected 6 days previously inhibited the intracellular growth of L. pneumophila. Antigen-stimulated spleen cell factor prepared from infected guinea pigs inhibited the intracellular growth of the organism in macrophages obtained from uninfected animals. Antigen-stimulated spleen cell factor prepared from spleen cells treated with anti-guinea pig T-cell monoclonal antibody did not inhibit growth. The activity of antigen-stimulated spleen cell factor was labile to pH 2 treatment, and the factor could not be absorbed by L. pneumophila antigen, suggesting that it contains gamma interferon. Our data show that T-cell-mediated immunity begins to work from an early period of infection with L. pneumophila in guinea pigs.

Functional and biochemical characterizations of avian T lymphocyte antigens identified by monoclonal antibodies

Seven monoclonal antibodies (mAb) were used to characterize antigens present on chicken T lymphocytes and on natural killer cells by flow cytometry, radioimmunoprecipitation and by effects on cell-mediated cytotoxicity and mitogen-induced proliferation. mAb CTLA8 and 5 stained 73% of thymus, 44% of spleen and 51% of peripheral blood lymphocytes (PBL), respectively, and immunoprecipitated 65- and 45-kDa proteins from detergent extracts of 125I surface-labeled thymocytes. Pretreatment of splenic lymphocytes with mAb CTLA5 and 8 in the presence of rabbit complement (C) eliminated the concanavalin A (Con A)-induced T cell proliferative responses. mAb CTLA3, 4 and 9 stained 43% of thymus, 36% of spleen and 18% of PBL, and immunoprecipitated 33-35-kDa proteins. Pretreatment of spleen cells with mAb 4 or 9 plus C reduced, but did not eliminate, the Con A-induced proliferative response and significantly reduced both major histocompatibility complex (MHC)-restricted and non-MHC-restricted cellular cytotoxicity. mAb CTLA1 and 6 stained 58% of thymus, 13% of spleen and 19% of PBL. mAb CTLA1 and 6 immunoprecipitated a 65-kDa protein. mAb CTLA1 and 6 had no effect on the Con A-induced blastogenesis and CTLA6 caused no decrease in virus-specific cytotoxic T lymphocyte and natural killer activity. These results indicate that (a) mAb CTLA5 and 8 identify antigens on mature T lymphocytes that are similar in tissue distribution, molecular mass and function to the mammalian CD5 antigen; (b) mAb CTLA3, 4 and 9 detect the avian homologue of CD8 antigen; and (c) mAb CTLA1 and 6 identify the avian homologue of CD4 antigen.

Peripheral blood mononuclear cell-mediated cytolytic activity during cytomegalovirus (CMV) infection of guinea pigs

Inbred Strain-2 guinea pigs exhibited endogenous peripheral blood mononuclear cell (PBMC)-mediated cytolytic activity against xenogeneic MA104 targets and guinea pig cytomegalovirus (gpCMV)-infected syngeneic and allogeneic targets. This endogenous cytolysis was unaffected by monoclonal T-cell antibody depletion but was diminished by removal of plastic adherent cells. In nonadherent effector populations, cytolysis was mediated predominately by large granular lymphocytes (LGL). During gpCMV infection, cytolysis of both target types was augmented (MA 104 for 3 weeks and gpCMV targets for 10-14 weeks). Augmented cytolysis of gpCMV targets was MHC-unrestricted and was diminished by removal of plastic adherent cells or monoclonal antibody depletion of T-cells, being found largely in LGL enriched populations. A role for this augmented activity in limiting gpCMV infection in inbred guinea pigs is suggested by the temporal association of augmented cytolysis of gpCMV targets with the cessation of viremia and clinical recovery.

The development and analysis of species specific and cross reactive monoclonal antibodies to leukocyte differentiation antigens and antigens of the major histocompatibility complex for use in the study of the immune system in cattle and other species

We examined the potential of developing a set of species specific and cross reactive monoclonal antibodies (MoAbs) for use in the study of the phylogenetic and functional relation of class I and class II antigens of the major histocompatibility complex (MHC) and leukocyte differentiation antigens in cattle and other species. Comparing immunization strategies demonstrated the number of hybrids producing cross reactive antibodies can be increased by hyperimmunization of mice with lymphoid cells from multiple species. Comparing various methods of assay (antibody-complement mediated cytotoxicity [CT], enzyme linked immunosorbent assay [ELISA] and flow microfluorimetry [FMF]), revealed FMF is the most useful technique for the primary assay of hybridomas producing MoAbs of potential interest. By using dual parameter and dual fluorescence analysis, we could determine whether a given MoAb reacted with mononuclear cells (lymphocytes and monocytes) and/or granulocytes, and also whether any two MoAbs of different isotype and specificity recognized antigens present on identical or separate populations of leukocytes. Comparing the patterns of MoAb reactivity with leukocytes obtained from cows, goats, sheep, pigs, horses and humans, as well as comparing the patterns of reactivity with a panel of lymphoid cell lines derived from cattle (with enzootic bovine leukemia) and humans (with various forms of leukemia), revealed sets of MoAbs reactive with unique antigenic determinants present on BoLA class I (15 MoAbs) and class II (9 MoAbs) antigens, and also MoAbs reactive with determinants present on leukocyte differentiation antigens (36 MoAbs). Dual fluorescence analysis demonstrated the antigens detected by some MoAbs are predominantly expressed on one lineage of leukocytes while others are expressed on two or more lineages of leukocytes. Dual and single fluorescence analysis also demonstrated the PNA receptor(s) is: expressed on T cells, granulocytes and class II antigen monocytes and absent or expressed in low amount on sIgM+ B cells and a newly defined Non T/Non B population of cells. The strategies described for identifying and analyzing the specificity of MoAbs demonstrate the feasibility of developing a set of cross reactive MoAbs for identifying homologous molecules in multiple species and delineating their functional and phylogenetic relation.

The role of lymphoid cells in antibody-induced suppression of the fourth component of guinea pig complement

Many laboratories have demonstrated that immunoglobulin production by B cells is controlled by networks of interacting lymphocytes and their products. Our laboratory has demonstrated that complement components produced by macrophages are also regulated by networks of interacting cells and humoral factors. Treatment of mice in vivo or guinea pig cells in vitro with anticomponent antibody specifically inhibits synthesis and secretion of the component by macrophages. We have further characterized the cellular basis for in vitro suppression of the fourth component of guinea pig complement. C4 suppression has been accomplished with dispersed spleen cells as well as intact splenic fragments. This facilitated examination of the cells responsible for long-term C4 suppression. The data suggested that C4 suppression required either cell contact or sufficient concentrations of soluble factors. Long-term suppression of C4 depends upon a lymphoid cell contained in the spleen and in lymph nodes but absent or in insufficient concentration in the peritoneum. The lymphocyte that actively maintains suppression was negative for the guinea pig T-cell marker detected by the monoclonal antibody mc8BE6. Therefore, the critical cell is either another T-cell subset or non-T lymphocyte. These data demonstrate that a network of interacting cells analogous to that proposed to regulate antibody synthesis is also involved in regulating some nonlymphoid cell products.

Thymocyte-dependent immunity to toxoplasmosis in the normal and immunocompromised guinea-pig host

Guinea-pigs made T-cell deficient by thymectomy and irradiation, and protected with syngeneic bone marrow cells (TXB) have a greatly reduced capacity to express normal cell-mediated immune functions, based on their poor responses to T-cell mitogens, prolonged acceptance of skin allografts, and susceptibility to the lethal effects of graft-versus-host disease. Further evidence for impaired T-cell activity in TXB guinea pigs was based on their inability to be fully sensitized to mycobacterial antigens, and increased susceptibility to an intradermally induced infection with the intracellular protozoan parasite, Toxoplasma gondii (RH strain). After challenge at multiple sites with 10(6) or 10(5) parasites, toxoplasmosis in thymus-intact, fully immunocompetent guinea pigs is a self-limiting and survivable infection, whereas the disease takes an acutely lethal course in the majority of TXB guinea-pigs. The latter also had more parasites disseminating to various tissues sites than their euthymic counterparts. The reduced capacity of TXB guinea-pigs to respond to mycobacterial products, and to generate anti-Toxoplasma immunity can be restored by an intravenous infusion of normal syngeneic thymocytes. These findings provide substantial direct evidence strengthening the concept that protection against toxoplasmosis is heavily dependent upon an intact T-cell component of the host's immune response.

Transfer of autoimmune encephalomyelitis with T lymphocytes in strain 13 guinea pigs

Experimental autoimmune encephalomyelitis (EAE) and/or tuberculin sensitivity were transferred to histocompatible recipients with myelin basic protein-stimulated and/or PPD stimulated guinea pig lymph node T cells previously separated by depletion of B cells ("panning") on rabbit anti-guinea pig Ig antibody-coated Petri plates. The depletion was augmented by complement-mediated lysis using mouse anti-guinea pig B-cell monoclonal antibody (31D2), rabbit anti-mouse Ig, and rabbit complement. B cells did not transfer EAE nor provide protection against active immunization with guinea pig spinal cord antigen.

Enhanced primary resistance to Treponema pallidum infection and increased susceptibility to toxoplasmosis in T-cell-depleted guinea pigs

Strain 2 guinea pigs made T-cell deficient by thymectomy and irradiation and protected with syngeneic bone-marrow cells (TXB guinea pigs) have a surprisingly high level of resistance to cutaneous syphilis and to the dissemination of treponemes to the draining lymph node. Compared with normal euthymic controls infected with Treponema pallidum Nichols, syphilitic TXB guinea pigs developed fewer and less severe skin lesions and their lymph nodes contained lower numbers of treponemes. Associated with this evidence for enhanced innate resistance was the ability of the TXB host to produce, during each test interval of a primary infection, more antitreponemal antibodies than that of their euthymic counterparts. Similar levels of partial protection against cutaneous and disseminated syphilitic infection and elevated antibody levels occurred in challenged normal guinea pigs passively immunized with lymphocytes from T. pallidum-infected TXB donors. In contrast, the capacity of the TXB host to be protected against a lethal infection with the unrelated intracellular protozoan parasite Toxoplasma gondii was greatly impaired unless it received an intravenous infusion of normal syngeneic thymocytes. These seemingly paradoxical results are explained primarily in terms of a residual T-helper-cell population in the TXB guinea pig which is large and competent enough to generate antisyphilis, but not anti-Toxoplasma, immunity.

Production of monoclonal antibodies defining guinea pig T-cell surface markers and a strain 13 Ia-like antigen: the value of immunohistological screening

The production and characterization of eight monoclonal antibodies (MAbs) against surface markers of guinea pig T-cells is reported. MAbs CT5 and CT7 define putative pan-T-cell markers. CT5, however, also reacts with the B-cell leukemic line L2C. MAb CT6 is reactive with less than 30% of peripheral T-cells. MAbs CT1, 2, 3, 4, and 8 are reactive with lymphocytes, but not with germinal center B-cells. In addition to the CT's, a MAb (CI-13.1) has been prepared that reacts with an Ia-like antigen on cells of strain 13 and outbred guinea pigs, but not with cells of strain 2 animals. CI-13.1 cross-reacts with human tissue sections: About 30% of the OKIa-positive dendritic cells in the human dermis are recognized by CI-13.1. In the course of production and characterization, various binding assays and an immunohistological method were used for determining the antibody specificity. Immunohistological screening was found to be the most informative method.