William H. Hildemann

Chronic Kidney Allograft Reactions In Rats

Chronic rejection of orthotopic kidney allografts occurred between inbred Fischer and Lewis rats with survival times up to 48 weeks in Fischer ← Lewis combinations and greater than 60 weeks in Lewis ← Fischer combinations. Lewis recipients of Fischer kidney grafts showed prolonged survival in spite of repeated, prompt rejection of subsequent Fischer skin grafts. In otherwise normal Lewis recipients, chronic rejection of Fischer kidney allografts was characterized by minimal loss of renal function, slow but progressive destruction of kidney parenchymal tissue, and persistent alloantibody production until the terminal stages of rejection. Survival and function of Lewis ← Fischer kidney allografts were similar to that of isografts, however; there was minimal cellular infiltration and destruction of the allograft compared to the reciprocal combination. Lewis recipients, sensitized by Fischer skin or kidney grafts, showed accelerated rejection of subsequent Fischer skin grafts. Moreover, Lewis rats sensitized with Fischer skin grafts rejected subsequent Fischer kidney grafts in an accelerated manner. These findings demonstrated the reciprocal immunogenicity and vulnerability of kidney and skin allografts in these strain combinations. Nevertheless, kidney allografts between Lewis and Fischer rats had prolonged survival times, even though skin allografts were rejected promptly. Differential susceptibility to immunological enhancement mediated by humoral alloantibodies probably contributed to the disparate survival times observed. Functional, histological, and serological evidence support, this hypothesis.

Integumentary allograft versus autograft reactions inCiona intestinaux: A protochordate species of solitary tunicate

Immunosurveillance or recognition of nonself from self may be regarded as a fundamental characteristic to preserve the integrity of the body in all vertebrates. Recent investigations of immune responsiveness in diverse invertebrates strongly suggest that they also have the ability to recogniz e and react against foreignness in specific ways, comparable to certain vertebrate immune responses (Hildemann and Reddy 1973). Quasi-immunorecognition in the form of allogeneic or intercolony incompatibility is shown by coelenterates (Ivker 1972, Hildemann et al. 1974, Theodor 1969) and colonial tunicates (Bancroft 1903, Mukai, 196%. Oka and Watanabe 1960, Freeman 1970a). Distinct lineages of advanced invertebrates represented by annelids (Cooper 1970, Duprat 1970) and echinoderms (Hildemann and Dix 1972) exhibit primordial cell-mediated immune responses toward allogeneic tissue grafts associated with specialized leukocytes, including lymphocyte-type cells. These specific rejection reactions were found to evoke at least short-term memory. Tunicates belonging to the phylum Protochordata occupy a unique position between advanced invertebrates and true vertebrates. Since many arguments favor the evolution of vertebrates from tunicates (Berill 1955), immunological investigation of this group promises insight into the origins of the elaborate adaptive immune systems of vertebrates. AUogeneic incompatibility or colony specificity is characteristic of all colonial tunicates. In addition, Tanaka and Watanabe (1973) had shown typical nonfusion reactions inBotryllus colonies with destruction of cells in the tunic ofallogeneic colonies. Reaction to foreign bodies, like broken-glass fragments, and mobilization of specialized cell types, like vanadocytes, in encapsulation reactions has been reported in a solitary tunicate Molgula manhattensis (Anderson 1971). But no specificity was observed in encapsulation of autoand allografts transplanted into the branchial sac. These studies are equivocal in the sense that grafts were transplanted to abnormal heterotopic sites.

Characteristics of transplantation immunity in the sponge, Callyspongia diffusa.

Very extensive polymorphism of histocompatibility (H) molecules in the sponge Callyspongia diffusa was revealed by the incompatibility found among 480 different allogeneic pairings without exception. This represents some 960 individual clones utilized as alloparabionts or sources of fitted allografts. Consistent cytotoxic reactivity provoked by allogeneic cell surface contact in Callyspongia is manifest in a continuum of strong to weak histoincompatibilities; however, strong reactions are most frequent at normal temperatures of 23 to 27 C. The directionality, vigor, and timing of alloparabiotic rejection in this species all depend mainly on the genetic constitutions of the interacting clones. Replicate interclonal combinations yield essentially identical rejection reactions, and differences in graft dosage had no effect on either the direction or intensity of allocytotoxicity. Alloreaction times are inversely proportional to the strength of the H barrier. Maximal allosensitization indicated by accelerated second-set reactivity was gradually achieved, as a function of the interclonal combination, after 2 to 8 days of primary contact. Heightened transplantation immunity or memory persists for at least 2 to 3 weeks after contact sensitization.

Allogeneic polymorphism and alloimmune memory in the coral, Montipora verrucosa.

Populations of the coral Montipora verrucosa exhibited very extensive allogeneic polymorphism revealed by parabiotic incompatibility among 890 different pairings of colonies (clones) without exception. More than 1,400 reciprocal histoincompatibilities were actually recorded because bilateral cytotoxicity was observed among most of the alloparabionts tested. This “uniqueness of the individual” in terms of cell surface histocompatibility (H) markers is manifest in the whole spectrum of possible incompatibilities from strong to moderate to weak. The directionality, severity, and rate of rejection were mainly determined by the genetic constitutions of the interclonal parabionts. Allograft reaction times were closely temperature dependent and inversely related to the strength of the H barrier. Heightened alloimmunity or early memory was demonstrable after only 2 days of presensitization and became maximal after 4 to 8 days. After prolonged primary immunization, potent alloimmune memory persisted for 4 weeks, but disappeared after 8 to 16 weeks. Immunological primitiveness in corals may therefore be reflectd in the lack of long-lived memory as found among vertebrates.

Cellular organization in the marine demosponge Callyspongia diffusa

Fine-structural analysis of the tissues of the marine demosponge Callyspongia diffusa was carried out using scanning electron microscopu and ethanol cryofracture. Micrographic data reveal the pathway of water movement through the sponge, and allow accurate measurement of the dimensions of successive structural filters in the aquiferous system. Understanding the organization and cytoarchitecture of the normal tissues of this sponge provides a basis for comparison where histopathology is being investigated, e.g. in allograft rejection reactions.

MECHANISMS OF TUMOR-SPECIFIC ENHANCEMENT VERSUS RESISTANCE TOWARD A METHYLCHOLANTHRENE- INDUCED MURINE SARCOMA

SUMMARY Immunological responses to the tumor-specific transplantation antigen (s) of a methylcholanthrene-induced sarcoma (BFM2) were studied in C57BL/10 mice. Host resistance or active tumor enhancement was selectively induced. Cell-mediated responses were evaluated by peripheral blood small lymphocyte counts and adoptive transfers in tumor-bearing mice, while a cytotoxic microassay and passive transfers of whole sera, IgG, and IgM fractions were used to test antibody activities. Cell-bound activity was associated with resistance during a critical period of 15 days following challenge. IgM antibody from resistant mice was highly active in vitro and in passively curtailing tumor growth in vivo; this antibody may contribute to tumor resistance. Passive enhancement of BFM2 growth was induced only by the IgG fraction from sera of either resistant animals or hosts with actively enhanced tumors. The divergent anti-BFM2 responses in different hosts indicate that peripheral inhibition does not provide a comprehensive explanation of enhancement and that central inhibition or regulation of immunocyte function probably provides an additional mechanism.

Specific immunorecognition by histocompatibility markers: The original polymorphic system of immunoreactivity characteristic of all multicellular animals

The existence of two immunorecognition systems, theH system of cell-mediated immunity and theIg system of antibody-mediated immunity, is proposed. TheH system, based on polymorphism of cell-surface histocom-patibility markers, is postulated to have originated in multicellular invertebrates, probably beginning with coelenterates. Subsequent differentiation and diversification of immunocytes, associated with increasing physiological complexity in phylogeny, are postulated to have led to the addition of a regulatoryIg system at the level of primitive chordates or fishes. Progressive integration of theH andIg systems then provided T-B lymphocyte collaboration and the immunoregulatory network characteristic of higher vertebrates. Experimental tests are suggested for the hypothesis of a two-component system of specificH-marker immunorecognition, leading to nonspecific cytotoxic reactions mediated by nonantibody proteins.

Frequency of intercolony graft acceptance or rejection as a measure of population structure in the sponge Callyspongia diffusa

The sponge Callyspongia diffusa showed a rate of graft acceptance ranging from 5 to 23% between colony pairs tested at random from a highly localized population occurring on a small fringing reef flat in Kaneohe Bay, Oahu, Hawaii. The frequency of graft compatibility varied inversely with distance between the colonies over a range of from 0.1 to 11.9 m. Pairs of colonies in close proximity (5 to 50 m), but from opposite sides of deep channels, were invariably incompatible. Likewise, graft acceptance was not observed for colony pairs taken from different reefs of the bay and separated by a distance of from 2 to 3 km. C. diffusa propagates sexually by production of larvae and asexually by means of branch fragments. Graft rejection implies genetic non-identity, whereas acceptance implies identity. The observed spatial pattern of immunogenetic similarity suggestes that rate of graft acceptance is directly proportional to the extent of successful asexual reproduction within a given population. Conversely, rate of graft rejection appears to reflect the importance of sexual means of reproduction, which produces new combinations of histoincompatibility genes. Extensive genetic polymorphism at the locus or loci controlling graft acceptance and rejection is apparent in this species. Our findings are consistent with the “uniqueness of the individual” concept; postulation of “limited strain diversity” or “one shared allele yields tissue compatibility” is untenable in this species.

CYTOTOXIC TRANSPLANTATION IMMUNITY IN THE SPONGE TOXADOCIA VIOLACEA

The Hawaiian sponge, Toxadocia violacea, exhibited discriminating transplantation immunity in an extensive series of allogeneic and xenogeneic parabioses. Cytotoxic alloincompatibility occurred without exception, but with differing degrees of severity. The allorejection reactions developed more rapidly than has been observed in any other animal species. An intense tissue-bridging reaction in allogeneic contact zones preceded acute soft tissue destruction; the cytotoxic reactivity was usually restricted to the immediate zone of direct contact. The median reaction times were closely temperature-dependent and much accelerated at higher temperature. Specific, short-term alloimmune memory was revealed by second-set and third-party graftings. Extensive allogeneic polymorphism was evident from the invariable rejection observed among more than 140 different pairings. Xenograft reactions between Toxadocia violacea and Callyspongia diffusa were characterized by acute cytotoxicity, immune memory, and a qualitative change in secondary versus primary responses.

AFFERENT SENSITIZATION AND EFFERENT CYTOTOXICITY IN ALLOGENEIC TISSUE RESPONSES OF THE MARINE SPONGE CALLYSPONGIA DIFFUSA

Allogeneic branches of the marine sponge Callyspongia diffusa were paired either in parabiosis or as allografts. To examine the specificity of the allogeneic rejection process, naive second sets and third parties were substituted in the midst of primary allogeneic tissue responses. Other experiments were conducted with 0.2-, 0.8-, 3.0-, and 5.0-μm pore size membrane barriers separating various combinations of naive and presensitized allogeneic paired sponges. The results of these experiments demonstrate that both the afferent and efferent phases of allograft rejection in Callyspongia diffusa depend on direct allogeneic cell contact. Cytotoxic reactivity does not involve a readily diffusible cytotoxic molecule. Moreover, the specificity of allogeneic sponge graft rejections resides in the early recognition or afferent phase; once the effector response is generated or turned on, subsequent allogeneic cytotoxicity is nonspecific.