John W. Shonnard

The major histocompatibility complex of the rat.

Immunogenetic studies in the rat began with the investigation of blood group antigens (1-7) and evolved into the investigation of histocompatibility antigens and transplantation phenomena (8-17). In the course of this work, several nomenclature systems evolved that were eventually reconciled in a series of comparison studies (18-24). The biennial Workshops on Alloantigenic Systems in the Rat held under the aegis of the Transplantation Society (24) have provided the forum for the continued evolution of this field. In addition, several reviews (24-31) and books (32-35) have provided periodic summaries of different aspects of rat immunogenetics. This review will focus on the structure of the major histocompatibility complex (MHC) of the rat from the serological, biochemical, and molecular points of view.

Small renal adenocarcinoma with metastases.

A case of a 9 mm. renal adenocarcinoma with widespread metastases, including multiple osteoblastic metastases, is presented. An extensive clinical investigation to identify a primary lesion in this patient was negative, including prostatic biopsy, serum electrophoresis, bone marrow biopsy, excretory urography, renal arteriography and abdominal computerized axial tomography scan. Examination at autopsy documented a small adenocarcinoma of the right kidney with local capsular invasion and metastases to the lungs, para-aortic lymph nodes and vertebrae. The differential pathologic and clincal features separating renal adenoma from adenocarcinoma are discussed.

Polymorphism of the major histocompatibility locus in the wild Norway rat

Specific alloantisera against the eight Ag-B groups found in inbred strains of rats were capable of reacting with all wild Norway rats (Rattus norvegicus) tested. Absorption studies, antisera production, and progeny testing involving wild rats showed that the antigenic specificities detected in the wild rat population were similar, if not identical, to the Ag-B antigens present in inbred strains. Xenoantisera prepared in rabbits against rat erythrocyte antigens (Ag-C1 and/or C2) reacted with erythrocytes from each wild rat tested. Progeny testing involving these erythrocyte antigens was identical to that observed in inbred strains. The restricted genetic polymorphism of theAg-B alleles in the wild rat population suggests that the functional and evolutionary significance of the major histocompatibility complex in the rat may not depend upon a high degree of genetic variability.

Genetic studies in inbred rats. II. Relationship between the major histocompatibility complex and mixed lymphocyte reactivity

The relationship between the mixed leukocyte reaction (MLR) and the serologically defined antigens of the major histocompatibility complex was examined in twenty‐three strains of genetically inbred rats. Interstrain cell combinations involving representative members of the different major Ag‐B groups were associated with significant MLR responses. Strain combinations within a single Ag‐B group were never associated with significant MLR responses, suggesting that non‐Ag‐B loci probably do not play an important role in MLR reactivity among inbred strains of rats. The WKA and KGH strains, representing newly defined histocompatibility groups, were also examined. The WKA strain (Ag‐B8) showed positive MLR responses against representative members of all the different Ag‐B groups, including the KGH strain. The KGH strain (Ag‐B7) had positive MLR responses against all Ag‐B groups except Ag‐B1: no reactions occurred with three strains in this group, and inconsistent and weak reactivity was observed with a fourth strain (F344).

Eosinophilic Pyeloureteritis: Report of a Case

A case is reported of ureteral obstruction that was owing to eosinophilic pyeloureteritis, a previously unrecorded entity. The microscopic findings of extensive fibrosis and a relatively mild eosinophilic infiltrate were similar to those found in a series of eosinophilic cystitis, which was reported recently from this laboratory. Also, local injury appears to initiate some examples of eosinophilic cystitis and in the present case there was a striking history of injury 1 month before the symptoms of ureteral obstruction.

Genetic and immunological characterization of naturally occurring recombinant B3 rats

The B-stock population of rats was bred for homozygosity at the loci controlling coat color. In this process, theAg-B1 andAg-B3 haplotypes became fixed in Hardy-Weinberg equilibrium. Extensive immunization and absorption studies showed that the specificities in the B-stock rats homozygous for theAg-B1 haplotype were the same as those found in the inbred F344 strain (Ag-B1), and that the specificities in the rats homozygous for theAg-B3 haplotype were the same as those found in the inbred BN (Ag-B3) strain. A homozygous line derived from the rats carrying theAg-B3 haplotype (B3) has the mixed lymphocyte reactivity and antibody responsiveness to poly (Glu52Lys33Tyr15) characteristic of the inbred strains in theAg-B4 group. Thus, it represents a naturally occurring recombination between the loci controlling MLR and immune responsiveness, on the one hand, and those controlling the Ag-B antigens on the other. Antibody responsiveness segregated with theAg-B3 haplotype in crosses between the B3 homozygotes and the low responder BUF and M520 strains; hence, this recombination is a stable one. There was no linkage of antibody formation or haplotype to coat color. The finding of a strain with a naturally occurring recombination in the major histocompatibility complex between the loci controlling mixed lymphocyte reactivity and the Ag-B histocompatibility antigens provides evidence for the separateness of these loci. Since the portion of the genetically determined mechanism controlling antibody responsiveness which is linked to the MHC was that characteristic of the MLR type, it too must lie outside the region defined by the serological specificities of theAg-B haplotype.

GENETIC STUDIES IN INBRED RATS. VI. LINKAGE RELATIONSHIPS OF MIXED LYMPHOCYTE REACTIVITY, SEROLOGICALLY DEFINED ANTIGENS (Ag‐B, Ag‐C) AND THE IMMUNE RESPONSE TO POLY(Glu52Lys33Tyr15)

The Ag‐B allotype, mixed lymphocyte reactivity (MLR) and the immune response to poly(Glu52Lys33Tyr15) were assayed in male rats from the F2 hybrid and two back‐cross generations of the F344 and DA strains in order to investigate the structure of the rat major histocompatibility complex. No disparity between Ag‐B type and mixed lymphocyte reactivity was found in 263 animals. The immune response to poly(Glu52Lys33Tyr15) was closely linked to the Ag‐B locus, and both antibody production and the delayed hypersensitivity response were under polygenic control. These results suggest that the genetic loci which determine these responses in the rat are closely linked and that recombinational events between the Ag‐B and MLR loci are infrequent.

GENETIC STUDIES IN INBRED RATS. IV. XENOANTISERA AGAINST RAT ERYTHROCYTE (Ag-C) ANTIGENS*

Antibodies to the erythrocyte Ag‐C antigens were raised by immunizing New Zealand white rabbits with rat red cells. Evidence that Ag‐C antigens are not on lymphocytes includes: (1) Ag‐C could not be detected on rat peripheral, splenic or thymic lymphocytes by lymphocytotoxicity using anti‐Ag‐C antisera, (2) xeno‐antisera prepared against rat lymphocytes from which Ag‐B antibodies were absorbed did not agglutinate rat red cells, and (3) absorption of reagent Ag‐C antisera with lymphocytes did not remove the anti‐Ag‐C activity. Platelets also failed to absorb Ag‐C antibodies from reagent anti‐Ag‐C antisera. The mixed lymphocyte reaction between strains within the same major histocompatibility (Ag‐B) group but differing in Ag‐C type showed no stimulation. This finding corroborates the studies which failed to demonstrate Ag‐C on lymphocytes. Isoagglutinins for red cells were not detected in any of the strains of rats tested, but rabbit xenoagglutinins to rat and sheep red cells were found. Reagent Ag‐C antisera were used to type some previously unreported strains of inbred rats.

The in vitro lymphocyte proliferative response to poly(Glu52Lys33Tyr15) in inbred rats

A significant in vitro antigen-induced lymphocyte proliferation to poly(Glu 52 Lys 33 Tyr 15 ) was observed in sensitized splenic lymphocytes from the DA strain of rats. In segregating F2 and backcross populations the response was linked to the major histocompatibility (Ag-B or H-1) complex. Nylon wool column purification of splenic lymphocyte preparations demonstrated that the proliferative response was thymus-dependent. Alloantisera produced against lymphocytes were capable of inhibiting the proliferative response and absorption studies suggested that the antibody specificities responsible for inhibition were directed at least in part against the serologically defined histocompatibility antigens present on erythrocytes.

THE AVIDITY OF IgM ANTIBODY IN HIGH AND LOW RESPONDER RATS

This study examined IgM antibody produced by highly responding ACI and poorly responding F344 rats following immunization with poly(Glu52Lys33Tyr15) or poly(Glu32Lys33Tyr15) aggregated with methylated bovine serum albumin (MeBSA). The ACI rats produced both IgM and IgG plaque‐forming cells (PFC) following immunization with either form of antigen. The F344 rats did not respond to unaggregated poly(Glu52Lys33Tyr15), but they produced significant amounts of IgG PFC and extremely small amounts of IgM PFC after immunization with poly(Glu52Lys33Tyr15)/MeBSA. Both high and low responder rats had similar kinetic profiles of IgM antibody production, and this antibody had nearly identical avidity in both strains with no evidence for any maturation in avidity. thus, one of the genetic defects in the antibody response to poly(Glu52Lys33Tyr15) is an inability of the F344 strain to produce large amounts of IgM in response to this antigen.