Graft-versus-host response

In utero exposure of mice to benzo(a)pyrene (B[a]P) resulted in suppression of the antibody response to SRBC, which persisted for up to 78 weeks in the offspring.102 In a follow up study, injection of B[a]P from gestation day 11 to 17 resulted in suppressed antibody responses to SRBC, MLR and graft versus host responses (GvH). It was suggested that lesions caused by B[a]P in the developing immune system may predispose the host to the growth of neoplasms.103... 

Methotrexate is a folic acid antagonists that indirectly suppresses the synthesis of purine and is particularly effective in rapidly proliferating cell populations such as cancer. It depresses the primary and secondary antibody response, the homograft reaction, the graft-versus-host response, and the development of hypersensitivity. Methotrexate is used in the treatment of certain cancers. It is very toxic in long-term use, especially to the liver. The toxic effect of methotrexate is reversed by use of... 

Contamination of blood products with lymphocytes can lead to transfusion-induced reactions ranging from a mild fever to severe reactions such as alloimmunization and graft versus host disease (GvHD), in which the transfused lymphocytes (graft) survive the defensive immune reaction of the patient (host) and start a reaction which destroys the cells of the host. The patient also may develop an immune response to the human leukocyte antigen (HLA) type of the graft s cells and reject all platelet transfusions that do not match their own HLA system. The HLA system, found on blood platelets and lymphocytes, is more compHcated than, but similar to, the ABO blood group system of red cells. 

TCDD (reviewed in13). However, despite considerable effort, direct effects of TCDD on purified T cells in vitro have not been consistently demonstrated, and direct effects on T cells in vivo are difficult to prove. This issue was recently resolved by studies that compared the effects of TCDD on the graft versus host (GVH) response of T cells obtained from AhR+,+ and AhR C57B1/6 (B6) mice.66 Results showed that the CTL response of grafted AhR- - T cells was resistant to TCDD-induced suppression, while under the same conditions, the CTL response of AhR+,+ T cells was suppressed by > 90%. Furthermore, when CD4+ and CD8+ T cell subsets were isolated from AhR+,+ and AhR- - mice and then recombined prior to grafting, full suppression of the CTL was dependent on AhR expression in both T cell subsets. These results provide the first evidence for the requisite role of the AhR in T cells for TCDD-mediated suppression of T cell responses. Induction of CYP1A1 in purified T cells exposed to TCDD in vitro validates the presence of a functional AhR.6-7... 

Contrary to the findings in BN rats, in Lewis rats [202] mercuric chloride induces immunosuppression, the number of suppressor/cytotoxic cells increase in the spleen and lymph nodes, an inhibition occurs of T cell responsiveness to mitogens and alloantigens and there is a marked reduction of the local graft versus host reaction. 

The major risks associated with platelet transfusion are aUo-immunization and infection. Platelets rarely cause graft-versus-host disease (108,109). Allo-antibodies, especially anti-HLA antibodies, appear to be the major source of complications in patients given repeated platelet transfusions. These antibodies cause febrile reactions, but they can also be responsible for partial or complete... 

Because the production of cytokines (for example IL-1 or TNF-alfa) involved in the stimulation of cells responsible for graft-versus-host disease can be enhanced by hemopoietic growth factors, the use of growth factors after allogeneic transplantation is theoretically risky. However, in reviews of trials of G-CSF or GM-CSF in allogeneic bone marrow transplantation there were no increases in late engraftment failures, relapse rates, or exacerbation of graft-versus-host disease (54,61). 

PUVA is used most commonly in the treatment of psoriasis, vitiligo, and cutaneous T-cell lymphoma. However, up to 30 other skin diseases have been reported to be responsive to PUVA therapy. The most common of these include palmarplantar pustulosis, polymorphous light eruption, dishydrotic eczema, atopic dermatitis, allergic contact dermatitis, actinic reticuloid, solar urticaria, pityriasis lichenoides, and graft versus host disease. 

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