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This manuscript reports the demographics, education and training, professional activities and lifestyle characteristics of 171 members of the American Society of Transplant Surgeons (ASTS). ASTS members were sent a comprehensive survey by electronic mail. There were 171 respondents who were 49 ± 8 years of age and predominantly Caucasian males. Female transplant surgeons comprised 10% of respondents. ASTS respondents underwent 15.6 ± 1.0 years of education and training (including college, medical school, residency and transplantation fellowship) and had practiced for 14.7 ± 9.2 years. Clinical practice included kidney, pancreas and liver organ transplantation, living donor surgery, organ procurement, vascular access procedures and general surgery. Transplant surgeons also devote a significant amount of time to nonsurgical patient care, research, education and administration. Transplant surgeons, both male and female, reported working approximately 70 h/week and a median of 195 operative cases per year. The anticipated retirement age for men was 64.6 ± 8.6 and for women was 62.2 ± 4.2 years. This is the largest study to date assessing professional and lifestyle characteristics of abdominal transplant surgeons.

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The addition of 3M KCl-extracted donor antigen (HAg) to immunosuppressive therapy with 16 Gy total lymphoid irradiation produces a significantly higher fraction of Wistar-Furth (WFu) recipients displaying indefinite survival of heterotopic buffalo (BUF) heart allografts, namely 80 versus 20%. The experiments presented herein analyzed the direct activity as well as estimated the potential precursor numbers at 1 and 3 months in treated recipients. At 1 month post-TLI/HAg therapy, recipients showed reduced proliferative responses in mixed lymphocyte reactions (MLR) in a specific pattern toward donor but not third-party stimulators. Both TLI/Graft and TLI/HAg/Graft groups showed a higher frequency of BUF antigen-directed T-cytotoxic cells (fTc) than TLI-treated, but nontransplanted, WFu hosts. In addition, the TLI/HAg group alone displayed alloantigen-specific suppressor cells that suppressed the MLR proliferative responses of normal spleen T cells against donor, but not third-party, alloantigens. At 3 months postirradition, both TLI/Graft and TLI/HAg/Graft groups displayed variable MLR proliferative responses toward donor and third-party alloantigens. Whereas nontransplanted, TLI-treated WFu rats recovered their fTc to normal levels at 3 months, the TLI and TLI/HAg treated recipients bearing functional heart allografts demonstrated significantly decreased splenic fTc. These results show that reduced numbers of cytotoxic cell precursors may afford more reliable indices of prolonged heart allograft survival than MLR responses. The observations suggest that TLI/HAg transplant hosts display both reduced cytotoxic precursors and activated suppressor elements.

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The synergistic effect of total lymphoid irradiation with KCl-extracted donor type antigen (H-Ag) was examined in the rat cardiac graft model. TLI therapy alone of 10, 16, and 20 Gy achieved by a 2 Gy daily treatment of WFu recipients produced modest prolongation of BUF heart survival to median survival times (MST) of 11, 26, and 30 days, respectively, in comparison with normal control (MST = 6). The TLI immunosuppressive effect was significantly potentiated with donor H-Ag when combined with 16 (greater than 100 days) but not with 10 or 20 Gy TLI therapy. This effect was specific: 16 Gy TLI treated recipients of BUF hearts rejected their grafts in a MST of 27 days when treated with third-party BN H-Ag. The state of unresponsiveness was transferable to 6 Gy total-body-irradiated WFu recipients of BUF hearts with 60 x 10(6) purified T cells isolated from TLI/H-Ag-treated rats (greater than 100) but not from normal controls (MST = 6). In vitro analysis of nontransplanted WFu rats 1-4 weeks after completion of 16 Gy TLI therapy alone demonstrated a nonspecifically reduced MLR proliferative response as well as the presence of potent nonspecific suppressor cells (NSC). By 3 or even 6 months post-TLI, W3/25- NSC displayed persistent suppressive activity and inhibited normal proliferative response to alloantigens. Limiting dilution assay revealed that the frequency of T cytotoxic cells (fTc) was severely decreased to 1:63111 at one day and to 1:16488 at one week postirradiation in comparison with normal control (1:2551). At 3 and 6 months the fTc of 1:2301 and 1:2040, respectively, approximated normal levels. These combined in vivo and in vitro results demonstrate that 16 Gy TLI therapy induces an unresponsiveness mediated by NSC and that the administration of donor type H-Ag facilitates the generation of potent regulatory T cells capable of inducing prolonged heart allograft survival.

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