Sex-dependent local cellular immunity to alloantigens.

A local component of cellular immunity was detected in mice that had been immunized against histocompatibility antigens. The status of this local immunity was determined using a node-onto-kidney (NOK) assay in which lymph nodes draining the site of immunization as well as distant (nondraining) lymph nodes of the immunized mice were grafted onto the kidneys of mice of the immunizing strain. In this assay, the weight gained by each node piece was taken as a measure of its immunological responsiveness. The responsiveness of a draining lymph node was directly compared with that of a distant node after both had been grafted onto the same host kidney. We consistently found that the draining lymph nodes of immunized male mice were more responsive than their distant nodes, whereas the draining lymph nodes of immunized female mice were less responsive than their distant nodes. Male mice were converted to the female pattern of hyporesponsiveness in the draining nodes by performing bilateral orchidectomy, suggesting that the male pattern depends upon the presence of testicular hormones. Additional studies showed there was a significant reduction in the reactivity of uterine draining lymph nodes during both syngeneic and allogeneic pregnancy, raising the possibility that the female pattern of hyporesponsiveness facilitates fetal survival by reducing the maternal immune response to fetal antigens and alloantigens during pregnancy.

Pregnancy-induced alterations in graft-versus-host responsiveness of uterine-draining and peripheral lymph node cells toward fetal alloantigens.

The popliteal lymph node assay was used to assess the effects of allogeneic pregnancy on the graft-versus-host (GVH) responsiveness of maternal uterine-draining and peripheral lymph node cells toward fetal alloantigens. These two cell populations were obtained from three groups of female mice: BALB/c virgins, BALB/c females 13 days pregnant by C3H males, and BALB/c females 13 days pregnant by BALB/c males. Recipients of the donor cells were (BALB/c x C3H)F1 and (BALB/c x C57)F1 hybrids. Uterine-draining lymph node (UDLN) cells at day 13 of an allogeneic pregnancy were specifically hyporesponsive toward fetal alloantigens compared to peripheral lymph node cells from the same donors. There was no difference in responsiveness between uterine-draining and peripheral lymph node cells in virgin or syngeneically pregnant mice. Therefore, the local nodes draining the uteri of primigravid mice carrying allogeneic fetuses, but not syngeneic fetuses, showed a specific decrease in GVH activity toward fetal alloantigens.

Host treatment with cyclophosphamide elicits transient changes in graft-versus-host reactivity of donor cells.

We have investigated the effects of a single injection of cyclophosphamide (CY) in F1 host mice. One day after CY treatment, F1 host mice show increased susceptibility to graft-versus-host (GVH)-reactive parental strain spleen cells when measured by the popliteal lymph node (PLN) enlargement assay. F1 host mice challenged with parental strain cells 7 days after CY treatment show decreased PLN enlargement as compared with CY-untreated F1 hosts receiving parental strain cells. The PLN reactivity of normal F1 spleen cells injected into F1 hosts pretreated with CY was also measured. F1 spleen cells elicited marked PLN enlargement when injected into F1 hosts that were treated with CY 1 day previously. By day 7 after CY treatment of F1 hosts, F1 cells no longer produced significant PLN enlargement as compared to untreated F1 hosts receiving F1 cells. We discuss these results in terms of the possibility that CY initiates changes in host antigenicity that can lead both to an increase in responsiveness of GVH-reactive cells and to susceptibility to attack by syngeneic cells.

Local cellular immunity in the draining lymph nodes of mice after immunization with histocompatibility alloantigens.

Mice immunized with allogeneic cells exhibit a local component of cellular immunity that is confined to lymph nodes draining the site of immunization. After immunization of C3H mice by skin grafting or by i.p. or footpad injection of F1 hybrid spleen cells, draining lymph nodes show increased responsiveness toward the immunizing histocompatibility determinants for at least 3 months after immunization. This local component of immunity is not detected in a traditional graft-versus-host (GVH) assay of splenomegaly. To demonstrate this immunity, we used a GVH assay in which pieces of whole lymph nodes were grafted onto F1 hybrid host kidneys. The enlargement of each grafted node piece is taken as the measure of its immunological responsiveness. We interpret our results to indicate that this node-onto-kidney assay detects the contribution of a relatively immobile donor cell population that exerts its effects in lymph nodes local to, but not distant from, the site of immunization.

Activation and suppression of graft-vs-host reactions by cyclophosphamide.

We have investigated the effects of a single injection of cyclophosphamide (CY) on the graft-vs-host (GVH) reactivity of spleen cells from BALB/c mice. Six days after CY injection, spleen cells showed a broad range of reactivity when tested for their capacity to produce splenomegaly in young F1 hybrid recipients. Eight and 10 days after CY treatment, their capacity to produce GVH splenomegaly was markedly reduced. We also investigated the effects of untreated and CY-treated BALB/c spleen cells on the local GVH reaction that occurs when BALB/c lymph node pieces are grafted onto F1 host kidneys. Untreated BALB/c spleen cells augmented the local GVH reaction, whereas day 8 CY-treated BALB/c spleen cells reduced the local reaction. Day 6 CY-treated BALB/c spleen cells marginally reduced the local response and elicited considerable host splenomegaly. Day 6 CY-treated F1 hybrid spleen cells stimulated the local GVH reaction and did not produce splenomegaly. We interpret our results to indicate that CY treatment leads to a) the appearance on day 6 of a BALB/c cell population with increased GVH reactivity, b) the emergence of a suppressive mechanism by day 8 that results in reduced GVH reactivity, and c) an alteration at day 6 in F1 lymphoid cell antigenicity that enables these cells to stimulate an ongoing GVH reaction. We discuss our results in terms of the similar effects that CY has on GVH-reactive and autoreactive cell populations, and examine the possibility that the mechanisms that underlie GVH reactivity and autoreactivity are similar in that both involve imbalances of immunoregulatory cell populations..

Specific suppression of graft-versus-host responsiveness by incubation of donor lymphoid cells with a solubilized membrane fraction of host lymphoid cells.

BALB/c spleen cells were incubated with a solubilized membrane fraction (SMF) prepared from spleen and thymus cells of (BALB/c x C3H/He)F1 or (BALB/c x A/J)F1 hybrid mice. Cells incubated with (BALB/c x C3H/He)F1 SMF produced less graft-versus-host (GVH) splenomegaly in (BALB/c x C3H/He)F1 hosts than did untreated BALB/c cells. The reduction of GVH splenomegaly was specific, inasmuch as the GVH activity of (BALB/c x C3H/He)F1 SMF-treated and untreated cells was similar in (BALB/c x C57BL)F1 hosts, and BALB/c cells treated with (BALB/c x A/J)F1 SMF showed no alteration of GVH activity in either (BALB/c x C3H/He)F1 hosts or (BALB/c x C57BL) F1 hosts. The time course of splenomegaly did not differ for SMF-treated and untreated cells. Donor cells that were labeled with tritiated adenosine and treated with (BALB/c x C3H/He) F1 SMF produced a reduction in the amount of label appearing in (BALB/c x C3H/He)F1 host spleens but not in (BALB/c x C57BL)F1 host spleens. Mechanisms which could account for the ability of SMF to cause specific reductions in both GVH activity and host spleen labeling are discussed.

Synergism of thymus and bone marrow in the production of gra a5hilgard HR: Synergism of thymus and bone marrow in the production of graft-versus-host splenomegaly in x-irradiated hosts.

Graft-versus-host splenomegaly may be elicited from 500 R X-irradiated F(1) hybrid hosts if the hosts are injected with bone marrow cells and thymus cells from parental strain donors. Cells from thymus only or bone marrow only will not elicit graft-versus-host splenomegaly in these hosts. In this requirement for cells from both sources, the bone marrow cells play a nonimmunologic, proliferative role in the splenomegaly, and the thymus cells carry out the immunologic attack. Thus the mechanism of this synergism is quite different from that reported for the humoral immune response to sheep erythrocytes in which both thymus and marrow interact in the production of the specific immunologic response itself.

Sea urchin response to foreign substances.

An assessment of the response of Strongylocentrotus purpuratus to substances injected into the coelom shows that (i) foreign molecules are cleared from the coelomic fluid more rapidly than native molecules, (ii) coelomocytes can respond selectively to albumins of human and bovine origin, and (iii) immunization attempts fail to elicit accelerated coelomocyte uptake or accelerated clear-with antigen.