Lymphocytes and transplantation immunity

Induction of hair regrowth in the alopecia site of IFN-gamma knockout mice by allografting and IFN-gamma injection into the transplantation site

We previously demonstrated that around 6 weeks of age most of the interferon-gamma (IFN-gamma)(-/-) but none of the IFN-gamma(+/+) C57BL/6 mice began to lose hair in their dorsal or occipital areas or both and that a single s.c. injection of IFN-gamma into IFN-gamma(-/-) mice at 3 but not at 8 weeks of age (or later) could protect all the mice from alopecia. Here, we report hair regrowth in the alopecia site of IFN-gamma(-/-) mice at 8 weeks of age (or later) by the combination of IFN-gamma and allografting. Skin or tumor allografting and IFN-gamma injections into the transplantation site induced hair regrowth in the alopecia site of IFN-gamma(-/-) mice at 8-66 weeks of age, whereas IFN-gamma injections into the hairless site or allografting alone was ineffective in causing the hair regrowth. Histologic findings showed that the hair cycle in the region of alopecia of IFN-gamma(-/-) mice was blocked at the anagen stage and that in the IFN-gamma(-/-) mice treated with IFN-gamma and allografting, the cycle was at the telogen stage. The therapeutic effects were maintained for >1 year.

Permanent skin replacement using chimeric epithelial cultured sheets comprising xenogeneic and syngeneic keratinocytes

The present study was undertaken to evaluate the possibility of permanent skin replacement using chimeric xenogeneic-syngeneic graftable sheets previously obtained in vitro. Newborn (<3 days old) BALB/c and human keratinocytes were isolated and cocultured in different ratios as follows: 50% BALB/c to 50% human and 25% BALB/c to 75% human keratinocytes. Four to 5 days after culture and prior to their grafting, all chimeric sheets contained both cell types in ratios similar to those used to seed the initial chimeric cultures. Fourteen and 30 days after chimeric sheet grafting onto BALB/c mice dorsum, the newly generated cutaneous tissue showed a histologically well-organized epidermis presenting basal and suprabasal cell layers. Cutaneous cells in these structures secreted laminin and type IV collagen in blood vessels, and at ground level of the dermoepidermal junction there were signs of physiologically active skin. Cell phenotyping revealed the presence of only syngeneic keratinocytes, whereas xenogeneic cells were passively eliminated without a total rejection of the chimeric implant. This selective and passive elimination of xenogeneic keratinocytes went through cellular and humoral immunity activation. Data suggest that this chimeric culture method can be used for cutaneous therapies such as large congenital nevi, skin ulcers, and extensively burned skin. Indeed, for large third-degree wounded skin treatment, this culture method may shorten the time (4-5 weeks) needed for cell growth and graftable sheet production. Moreover, since the ultimate aim in allogeneic and xenogeneic transplantation is to achieve an immunological acceptance and tolerance to these foreign tissues, the chimeric culture approach may provide ways to lighten tolerance phenomena on cutaneous tissue.

Effect of oxidation on the conformation of cell surface H-2 antigens detected by monoclonal antibodies

Periodate treatment of lymphoid cells is known to render them susceptible to nonspecific lysis by cytotoxic T lymphocytes. To detect alterations in cell surface molecules as a result of such treatment, we investigated the binding of antibodies to oxidized and nonoxidized lymphoid cells and found that oxidation selectively decreases the binding of some anti-H-2 and anti-beta 2m antibodies. This effect was not caused by loss of H-2 molecules from the cells, since the rate of exchange of cell surface beta 2m by exogenously added beta 2m was unchanged, and neither H-2 nor beta 2m molecules could be detected in the supernates of oxidized cells. Our findings suggest that oxidation alters the conformation of H-2 antigens in such a way as to reduce antibody binding. Such conformational changes may further affect the recognition of histocompatibility antigens by cytotoxic T cells.

Circadian rhythm of stimulated lymphocyte blastogenesis. A 24 hour cycle in the mixed leukocyte culture reaction and with SKSD stimulation

The in vitro measurement of stimulated T lymphocyte blastogenesis by the incorporation of 14C-thymidine can be shown to be an acceptable and precise measurement with highly significant variations in blastogenesis over a 24 hr period. This circadian rhythm for human T lymphocyte blastogenesis has been demonstrated with specific antigen (SKSD) and in mixed leukocyte culture (MLC). The hours of peak reactivity were different for the SKSD stimulation and the MLC reaction. This biologic cycle in T cell reactivity has significant implications for the immunologic response.

Energy requirements of the binding and lytic steps of T lymphocyte-mediated cytolysis of leukemic cells in vitro

The process of T lymphocyte-mediated destruction of target cells in vitro is temperature dependent and is suppressed by inhibitors of energy metabolism, but the energy requirements for the conjugation and lytic steps of the process are different. The conjugation step of lymphocytes and target cells is prevented by metabolic inhibitors and is dependent on temperature, increasing in the range from 2 degrees C to 22 degrees C. However, after lymphocyte-target cell conjugates are formed, they are stable at low temperatures (0 degree C) and in the presence of metabolic inhibitors. Thus, the formation but not the maintenance of lymphocyte-target cell conjugates is an energy-dependent process. In contrast to the conjugation step, which is influenced both by metabolic inhibitors and by temperature, the lytic step, which occurs only between 22 degrees C and 37 degrees C, is not affected by inhibitors of energy metabolism. The sigmoidal behavior of lysis as a function of temperature, showing a sharp inflection around 20 degrees C, can be explained in terms of the alteration of the viscosity of the membrane matrix of the target cells rather than as a general metabolic effect on the killer and target cells.

Pathogenesis of temperature-sensitive mutants of sindbis virus in the embryonated egg. I. Characterization and kinetics of viral multiplication

Exploratory experiments were performed with temperature-sensitive (ts) mutants of Sindbis virus for studies on viral pathogenesis in the embryonated egg, a host which is immunologically underdeveloped. Parent and mutants were found to be virulent at the permissive temperature (33 C), but only the mutants were attenuated at the nonpermissive temperature (38.5 C). The degree of attenuation varied with the mutant and the route of inoculation. Chicks which survived infection by ts mutants at a nonpermissive temperature weighed the same as controls and showed no obvious abnormalities on gross examination. Whenever death of the embryo at the nonpermissive temperature occurred after inoculation with a mutant, it was apparently due to the selection of a population of temperature-insensitive virulent revertants. Kinetic studies showed that, after inoculation of the chorioallantoic membrane and incubation at the permissive temperature, a number of cycles of virus multiplication and dissemination apparently occurred rapidly. At the nonpermissive temperature, multiplication was undetectable. Certain pathophysiological signs were seen in the slower, less virulent infections by the mutants at the permissive temperature that were apparently masked or obscured in the more virulent, rapid infection by the parent. From these results and those reported in a subsequent paper, it appears that ts mutants of viruses possess potential as valuable tools for analyzing pathogenesis and immunity in the intact animal host that are complementary to more conventional approaches which employ normal (temperature-insensitive) viruses.

Allograft tolerance: presumptive evidence that serum factors from tolerant animals that block lymphocyte-mediated immunity in vitro are soluble antigen-antibody complexes

Serum factors present in rats rendered operationally tolerant to skin allografts by inoculation of allogeneic bone-marrow cells as newborns inhibit or "block" the cytotoxic effect of immune lymphocytes in vitro. These blocking factors were specifically removed from tolerant serum by absorption with allogeneic cells and later eluted from the absorbing cells in glycine buffer (pH 3.1). Blocking activity of the eluted material was resolved into fractions of low and higher molecular weight, which may be soluble histocompatibility antigen and specific alloantibody, respectively. Both antigen and antigen-antibody complexes may block in vitro, depending upon the assay used.

Cell-mediated immunity and blocking serum activity to tolerated allografts in rats

W/Fu rats were neonatally inoculated with bone marrow cells from B/N rats and vice versa. Of the inoculated rats, some were capable of accepting a foreign (B/N or W/Fu) skin graft over the period of observation (i.e. for more than 100 days), while other rats rejected their skin grafts as early as control animals (within 8-12 days) or after a prolonged period of acceptance (20-96 days). Using a microcytotoxicity test, it could be shown that both those rats that rapidly rejected skin grafts and those that kept their grafts during the observation period had lymphocytes capable of destroying cultivated allogeneic cells from the respective strains with whose cells the rats had been inoculated as newborns. The degree of lymphocyte reactivity decreased upon time, so that 4 of 13 rats that had carried "tolerated" skin grafts over more than 84 days had lymphocytes which were nonreactive in the highest dose tested, and the degree of reactivity in the other 9 rats was less than seen early after tolerance induction. Rats that were capable of accepting skin grafts over prolonged periods of time had sera that could specifically block lymphocyte-mediated cytotoxicity, while sera from rats that had rejected their grafts did not block. Sera from rats that rejected their skin grafts after 20-96 days lost the blocking activity 3-10 days before rejection.

Immunologic rejection of diethylnitrosamine-induced hepatomas in strain 2 guinea pigs: participation of basophilic leukocytes and macrophage aggregates

The morphologic events associated with the immunologic rejection by strain 2 guinea pigs of ascites variants of two lines of diethylnitrosamine-induced tumors have been studied by light and electron microscopy. Tumor injection sites in the skin of control animals exhibited clusters of viable, actively mitotic tumor cells along with a modest inflammatory infiltrate composed of lymphocytes, macrophages, neutrophils, and rare basophils. In contrast, similar injections of either tumor line in specifically sensitized guinea pigs elicited typical delayed-type skin reactions associated with tumor cell necrosis and a more extensive inflammatory infiltrate including a selective increase in the number of basophilic leukocytes (12%, line 1, or 23%, line 10, of total inflammatory cells). That basophils may have a role in tumor resistance in vivo is suggested by the close anatomic associations observed between basophils and tumor cells, and by the fact that basophils were the only inflammatory cell to demonstrate a relative increase in frequency in the lesions of sensitized as compared with control animals. Moreover, intraperitoneal injection of line 1 tumor in specifically sensitized animals elicited a striking basophilia within 24 h. Unlike macrophages, basophils did not phagocytose tumor cells but did evidence occasional extrusion of granules and frequently exhibited loss of granule staining density, a change that may be related to release of mediator substances. Electron microscope studies of line 1 tumor rejection in the peritoneal cavities of specifically sensitized guinea pigs demonstrated aggregations of "activated" macrophages, lymphocytes, basophils, and damaged or dead tumor cells. These aggregates, held together by complex interdigitations of macrophage villi, closely resembled those occurring in vitro among peritoneal exudate cells whose migration from capillary tubes was inhibited by migration inhibition factor (MIF). Moreover, cells in these aggregates, as well as macrophages inhibited by MIF in vitro, lacked a normal coating of cell surface material.

Tumor immunity in vitro: destruction of a mouse ascites tumor through a cycling pathway

Lymphocytes in peritoneal exudate from BALB/(c) mice immunized against ascites leukemia EL4 are uniquely efficient at destroying (51)chromiumlabeled EL4 cells in vitro. The lytic process depends upon the number of lymphocyte-tumor cell interactions. Efector lymphocytes are not inactivated as a result of lethal contact but can interact repeatedly with tumor cells.

Rejection of ascites tumor allografts. I. Isolation, characterization, and in vitro reactivity of peritoneal lymphoid effector cells from BALB-c mice immune to EL4 leukosis

Peritoneal exudate cells (PEC), obtained after the rejection of EL4 leukemia by BALB/c mice, are much more effective in the specific in vitro destruction of (51)Cr-labeled EL4 cells than are spleen, thymus, lymph node, or peripheral blood lymphocytes. The presence of a large number of effector cells at the site of graft rejection is reflected in the potent cytolytic activity seen in vitro. Effector cells temporarily lose cytolytic reactivity when treated with trypsin but regain reactivity with time. This recovery occurs in normal as well as in immune serum. The destructive reactivity of PEC is increased when macrophages are removed. The remaining population of nonadherent PEC is composed primarily of small- to medium-sized lymphocytes. Complex tissue culture media are not needed, but there is a definite requirement for serum. The required serum component is heat stable, nondialyzable, and is not consumed during the reaction. The use of an ascites allograft system made these observations possible and permitted the isolation of those host cells intimately associated with rejection.

Immunological tolerance: "forbidden clones" allowed in tetraparental mice

Tetraparental (allophenic) mice, made chimeric at the eight-cell stage by joining two embryos from histoincompatible parental strains, were examined by a microcytotoxicity test. The results indicate that parental-strain fibroblasts are more effectively destroyed in vitro by lymph node cells from the tetraparental mice than by lymph node cells from the F(1) hybrid or either parental stain. The destruction by tetraparental lymph node cells is indistinguishable from that mediated by lymph node cells from previously immunized allogeneic animals. It can be prevented by serum from the tetraparental mice, but not by sera from the F(1) hybrid or the parental strain animals. The results suggest that a concomitant immunity and serum blocking effect, rather than a central failure of the immune response, may mediate some aspects of normal tolerance.

The lymphatic status of hamster cheek pouch tissue in relation to its properties as a graft and as a graft site

Hamster cheek pouch skin, transplanted to the side of an isogenic host's chest wall, retains its immunologically privileged status as evidenced by the prolonged survival of inlaid homografts of ordinary skin. Various findings sustain the premise that exemption from rejection by otherwise susceptible homografts in both intact pouch tissue and in established pouch skin isografts is due to an impediment in the afferent pathway of the immunologic reflex, i.e., to deficient lymphatic drainage. Although lymphatics were not apparent when dye was injected into pouch skin grafts or into grafts of ordinary skin sustained by them, lymph vessels were readily and consistently revealed by dye injected into intact trunk skin or established isografts of trunk skin. When suspensions of viable lymph node cells from specifically sensitized parental strain donors were injected superficially into either the intact skin or established grafts of normal skin on F(1) hybrid hamsters, a striking hypertrophy of the regional lymph nodes occurred, due to graft-versus-host reactivity. However, similar cell suspensions inoculated into intact pouch tissue or into pouch skin grafts on F(1) hamsters incited no regional lymphadenopathy, indicating the lack of appropriate pathways to the nodes. When skin homografts were inlaid eccentrically into pouch skin isografts, so that they were in contact with host skin at one edge, rejection occurred. Furthermore, rejection of long-established intrapouch skin homografts resulted if the hosts received: (a) small homografts of ordinary skin transplanted to conventional beds; (b) suspensions of donor strain pouch skin epidermal cells, injected intracutaneously; (c) lymph node cells from specifically sensitized donors of the same strain, i.e. adoptive immunization; or, (d) if a portion of the target homograft's perimeter was surgically approximated to body skin. Treatment of normal hamsters with two closely spaced pulses of ALS, although only marginally effective in prolonging the lives of homografts of trunk skin, enabled pouch skin homografts to survive for very long periods. The influence of this brief treatment with immunosuppressant was still demonstrable if challenge of hosts with the weakly immunogenic pouch skin homografts was delayed for 100 days.

Quantitative studies on the mixed lymphocyte interaction in rats. V. Tempo and specificity of the proliferative response and the number of reactive cells from immunized donors

These studies were designed to determine what influence prior immunization with homologous H isoantigens might have on the subsequent proliferative activity of lymphocytes from these animals in the mixed lymphocyte interaction. The results demonstrate the following: (a) Subcutaneous immunization with splenic cells from donors differing at the major H locus accelerates the tempo of the proliferative response to F(1) cells bearing these same antigens in the MLI, whereas antigen given systemically reduces the proliferative response. (b) The altered proliferative behavior is specific for the immunizing antigens. (c) The period after immunization during which the MLI displays an altered tempo is a short one, lasting not longer than 3 wk. (d) Whether they are derived from previously immunized or from normal donors, the proportion of lymphocytes responsive in the MLI is the same, even though the response profiles are different. These results suggest that in comparison to immune responses to other types of antigens, immunologic reactivity to the major H isoantigens already involves a large number of antigen-reactive cells in normal animals and that the proportion of these cells is not increased as a result of immunization. Rather, lymphocytes from immunized animals respond more rapidly to the presence of these antigens.

Cells involved in cell-mediated and transplantation immunity. II. A consideration of the functional identity of the cells involved in both humoral and cell-mediated immunity: a phylogenetic approach

The literature concerned with the types of cells that participate in the humoral and cell-mediated immune response has been reviewed. It is postulated that the initial cells that are involved in mediating both types of immunity are functionally identical in that both are antigen-reactive cells. In the case of the humoral immune response, the interaction of the antigen-reactive cells with the antigen leads to the release or transfer of "information" to the antibody-forming cell, resulting in the synthesis and secretion of antibody molecules. In the case of cell-mediated immunity, it is considered that the primitive antigen-reactive cell itself transforms into the sensitized cell which infiltrates the site of antigen administration.

Colony inhibition of fibroblasts from chimeric dogs mediated by the dogs' own lymphocytes and specifically abrogated by their serum

Nine canine irradiation chimeras were studied between 173 days and 7.5 years after 1200 to 1500 r of total body irradiation and transplantation of allogeneic bone marrow. Skin fibroblasts from chimeras and normal dogs were tested for colony inhibition by exposure to sera and peripheral blood lymphocytes from both chimeric and normal dogs. Lymphocytes from the chimeric dog were found to inhibit colony formation by its "own" fibroblasts while lymphocytes from other chimeras or from normal dogs did not. Serum from the chimera specifically abrogated this inhibitory effect. These results indicate that the immunological "tolerance" of the chimeric dog is mediated in vivo by blocking serum factors.

Quantitative studies on the mixed lymphocyte interaction in rats. IV. Immunologic potentiality of the responding cells

Studies were designed to provide some explanation for the unexpectedly large proportion (2%) of parental rat strain peripheral blood lymphocytes that are reactive in the mixed lymphocyte interaction (MLI) to a strong homologous transplantation isoantigen(s) present on cells from an F(1) donor. The possibilities considered involve nonspecific activation and multispecific reactivity on the part of the responding cells. The essential findings of this study were: (a) In 3-way mixed cultures, lymphocytes obtained from tolerant animals were not "recruited" to proliferate in the presence of cells from normal, isologous donors which were in the process of responding to F(1) cells bearing the tolerance-inducing antigens. With the use of chromosome markers and normal and tolerant parental strain donors of different sexes, the responsive cells were identified and proved to be derived from the normal and not the tolerant donor. (b) The magnitude of the proliferative response is increased additively when potentially reactive cells are exposed to two antigen systems simultaneously. On the other hand, doubling the "gene-dosage" of the genetic determinants of the H isoantigens employed had no effect on the responding cells. (c) A state of induced immunologic tolerance to one H isoantigen system did not alter the response capacity of cells from such a donor to an alternative antigen system. (d) Mixed cultures of heterologous cells from human and rat donors displayed a proliferative response which was less than that of homologous mixed cultures from human or rat donors. Prior sensitization of rat donors with human cells, however, greatly increased the mitotic activity of rat lymphocytes stimulated with human cells. These results suggest that the large number of responsive cells in the MLI do not include a significant number recruited or activated in some nonspecific manner. Rather, they appear to be fully specific in their response capacities so that a given lymphocyte does not react to a multiplicity of different antigens. The degree of proliferation depends on the number of different antigen systems presented to the responding population and not on the number of genetic determinants or "gene dosage" of a given isoantigen system. Finally, on a cell-for-cell basis, the peripheral blood lymphocyte population contains more cells reactive to histocompatibility isoantigens within the species than to heterologous antigens of a different species.