GENETIC MOSAICISM IN ADULT MICE OF QUADRIPARENTAL LINEAGE

Genetic mosaic mice can be produced by aggregating, during cleavage stages, the blastomeres of two embryos of different genotype into a single cluster, and by transferring the developing aggregates to the uterus of a surrogate mother. Substantial numbers of such composite embryos survive past birth. Among the living adult mosaic mice are individuals within which cells of markedly different immunogenetic constitution coexist. Through the incorporation of appropriate genetic markers into mosaics, many new possibilities now present themselves for analysis of biological problems during embryonic as well as adult life.

THE DIFFERING SURVIVAL OF NORMAL AND SENSITIZED SPLEEN CELLS TRANSFERRED TO ALLOGENEIC HOSTS

Normal and isoimmune C₃H and C57BL spleen cells were transferred intravenously into normal and irradiated allogeneic recipients and the fate of the donor cells determined by differential cytotoxicity and radioautographic techniques. It was found that spleen cells sensitized against their prospective recipients could be identified in the host's spleen for 1 day, whereas normal donor cells survived 2 to 3 days. Spleen cells presensitized with an indifferent antigen had survival times similar to normal donor cells. Irradiation of the recipients prior to cell transfer eliminated any difference in survival times between normal and presensitized donor cells in allogeneic hosts. It is concluded that the host plays an important role in the rapid destruction of spleen cells presensitized against host antigens. Experiments in which sensitized and normal C57BL spleen cells were mixed and transferred into normal C₃H mice indicated that as little as 5 to 10 per cent of the donor cell population need be sensitized for the entire mixture to behave as if it were obtained from a sensitized animal, as shown by its elimination in the 1-day interval.

STUDIES ON IMMUNOLOGIC RECONSTITUTION OF THYMECTOMIZED MICE

1. Immunologic function, growth, and longevity of neonatally thymectomized mice was restored by intraperitoneal administration of 100 to 400 million syngeneic, hemiallogeneic, or ailogeneic thymus cells from newborn or adult donors. Assays of the graft versus host capabilities of spleen cells from the animals restored with allogeneic cells showed that their immunologically competent cells are of donor histocompatibility characteristics. Such animals accepted skin grafts from mice of the cell donor strain, but rejected skin from a third strain. 2. Similar results were obtained when the neonatally thymectomized animals were treated with 10 to 100 million syngeneic, hemiallogeneic, or allogeneic cells from adult spleen. 3. In one strain combination, C₃H recipients and A donors, injected thymus or spleen cells apparently attacked host tissues, since the animals died very early of wasting disease. When this combination was reversed, A strain recipients treated with C₃H cells were reconstituted immunologically and physiologically. 4. Syngeneic or allogeneic adult spleen, grafted in the newborn period, reconstituted neonatally thymectomized mice, but all experiments involving grafting of newborn spleen failed. Immunogenetic analysis of the host spleen cells from two allogeneic spleen-grafted animals previously thymectomized showed that the reconstitution was entirely of donor histocompatibility characteristics. 5. Postthymectomy wasting disease was reversed by administration of 200 million adult syngeneic spleen or thymus cells. Immunologic recovery was confirmed by graft versus host assays of the spleens of the recovered animals and by application of allogeneic skin grafts. Some of the animals have been under observation for 42 weeks and appear to be normal. 6. The wasting syndrome in neonatally thymectomized mice was also reversed by injection of 200 million hemiallogeneic or allogeneic spleen cells. 7. Thymus grafts did not reverse wasting disease, whether the donors were adult or newborn, of the same strain or a different one. 8. Spleen, lymph node, and Peyer's patches from representative animals of the reconstituted groups were examined and compared with the tissues of untreated neonatally thymectomized mice and intact animals of the same strain. Tissues of normal cellularity and follicular organization were found in some of the reconstituted animals and also in mice with reversed wasting disease. Extreme deficit of the lymphoid tissues was rare in either group.

IMMUNOLOGIC STUDIES IN HUMAN ORGAN TRANSPLANTATION. I. OBSERVATION AND CHARACTERIZATION OF SUPPRESSED CUTANEOUS REACTIVITY IN UREMIA

Twenty-eight patients with chronic renal diseases and uremia were investigated with respect to their cutaneous responsiveness to a panel of antigens expected to elicit immediate and delayed hypersensitivity reactions. Compared to a control group, there was a marked decrease in the incidence of responses of both types. Eighteen patients received renal allografts from members of the control group and were available for restudy in the postoperative period prior to the institution of adrenal steroid therapy. Each recipient acquired delayed responsiveness with specificity identical with that of the kidney donor. The donor group was reactive to 49 antigens to which the recipients were non-reactive preoperatively. Postoperatively, 40 of these reactivities were observed in the recipients. This successful demonstration of the transfer of immunologically competent tissue in association with renal transplantation indicates that the cause of depressed cutaneous hypersensitivity in uremia is not an inability of the skin per se to react.

THE R OLE OF THE LARGE PERITONEAL MACROPHAGE IN TUMOUR HOMOGRAFT REJECTION

Images

THE EVOLUTION OF THE IMMUNE RESPONSE. 3. IMMUNOLOGIC RESPONSES IN THE LAMPREY

1. Studies of the immune response have been carried out in more than 1700 lampreys representing three stages in the life cycle of these animals. 2. Lampreys used in this study were unable to clear certain soluble protein antigens and bacteriophage and were unable to make antibodies to these antigens. Hemocyanin was cleared from the circulation. 3. The immune responses demonstrated in lampreys include the production of specific antibody to killed Brucella cells, the rejection of skin homografts, and the development of a delayed allergic response to old tuberculin. 4. A responsive proliferation of lymphoid cells occurred in the protovertebral arch following antigen-adjuvant stimulation. 5. Electrophoretic and immunoelectrophoretic analysis of lamprey serum revealed gamma globulin. Ultracentrifugal analysis of serum revealed proteins with sedimentation coefficients of 17S, 8S, 7S, and 3S. 6. The antibodies thus far observed in the lamprey are of relatively high molecular weight and destroyed by 2-mercaptoethanol. 7. In the lamprey it would appear that there is reflected the coordinate evolution of a primitive thymus, primitive spleen containing lymphoid foci, a family of lymphocytes in the peripheral blood and capacity for gamma globulin synthesis and expression of adaptive immunity.

HYBRID RESISTANCE TO PARENTAL MARROW GRAFTS: ASSOCIATION WITH THE K REGION OF H-2

Bone marrow of homozygous C57BL/10 donors was tested for growth in x-irradiated isogenic recipient mice, in (C57BL/10 X 129) F(1) mice, and in F(1) hybrids from congenic parents differing respectively, for an allelic substitution at one of the histocompatibility loci H-1, H-2, H-3, and H-4. All the tested H-2 heterozygotes resisted the transplantation of 10(4) parental marrow cells, whereas H-2 homozygotes were nonresistant, in spite of heterozygosity, at one or several other H loci. Findings in F(1) hybrids between C57BL/10 mice and mice carrying alleles resulting from crossing-over within the H-2 locus demonstrated that the hybrid resistance was associated with heterozygosity in the K region, but not in the D region of the H-2 locus.

THE CROSS-REACTIVITY AND TRANSFER OF ANTIBODY IN TRANSPLANTATION IMMUNITY

A close inomunochemical relationship of Forssman-type antigens in cells or in a methanol extract of guinea pig kidneys, lymph nodes, and platelets, of horse kidneys, and of sheep erythrocytes was demonstrated by complement-fixation, agglutination, and inhibition of hemolysis. The dissociation of antibody from several cross-reacting complexes and re-association with antigens of erythrocytes used for immunization was inferred from quantitative hemolytic assays. This preferential affinity of antibody for the antigen used for immunization is proposed as an immunochemical model for reactions which function in graft rejection phenomena wherein the donor and recipient tissues share cross-reacting antigens.

IMMUNOLOGIC INCOMPETENCE OF IMMUNOLOGICALLY RUNTED ANIMALS

1. Adult (A x C(57)Bl/1)F(1) hybrids regularly show runt disease when injected with adult spleen cells from A strain donors. This also occurs when A strain spleen cells are administered to adult C(3)H mice made tolerant of A strain tissue in the neonatal period. 2. Mice undergoing the graft versus host reaction fail to form antibodies to an intraperitoneal challenge of T(2) bacteriophage. This phenomenon was observed well before any of the other overt signs of runting had occurred. Further, inhibition of antibody production to T(2) phage by graft versus host reaction initiated at an interval following antigenic stimulation is demonstrated. 3. The basis for the immunologic incompetence of the host with respect to T(2) phage is presumed to be the attack of immunologically competent donor cells on the lymphoid cells of the recipient. 4. The failure of the injected parent strain cells to respond to the antigen used may imply immunologic commitment of these cells.