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Class I and II HLA typing was investigated before and at various intervals after a 10 Gy total body irradiation delivered over 4 h, prior to allogeneic bone marrow graft for various hematological malignancies, in 14 patients. A reliable class I HLA typing appeared to be possible in almost all cases 6-8 hours after the start of irradiation but was only possible in 5 patients after 24 h. Preliminary results with class II antigens might suggest a more marked "fragility" of this antigen class after irradiation. These results encourage the drawing of blood samples for HLA grouping as soon as possible after accidental whole-body irradiation.

Thirty-one selected patients with various haematological malignancies who received a 10 Gy-4 h total body irradiation (TBI) at the Institut Gustave Roussy 24 h before high dose cyclophosphamide for bone marrow transplantation, were prospectively evaluated for gastrointestinal symptoms, body temperature, consciousness, headache, xerostomia, parotiditis, ocular symptoms, blood pressure, and respiratory and cutaneous signs for 24 h. In spite of prophylactic administration of various anti-emetic agents, 90% of the patients experienced nausea and 80% experienced vomiting. An almost constant body temperature peak--up to 40.8 degrees C--was registered 6 h after the start of irradiation. No drowsiness was reported since the introduction of the new anti-emetic agent Ondansetron. Nearly half the patients (42%) complained of headache. The proportion of patients experiencing early (during TBI) xerostomia was 61%. 74% of patients complained of parotiditis in the first 24 h. Although this low dose rate whole body irradiation is not likely to be exactly replicated in many accidental human exposures, the incidence rate and the time-course of the observed prodromal phase symptoms may prove helpful for early triage in the case of accidental irradiation.

Most available clinical data strongly suggest a sparing effect of TBI fractionation for the lungs, liver, lens, the growth cartilage and, perhaps the prepubertal ovary; the usual fractionated TBI regimens, delivering from 12 to 15 Gy, appear to be constantly less toxic than the "standard" 10 Gy single dose TBI scheme. However, there is also some clinical suggestion, essentially coming from the T-depleted graft experience, that the largely used 12 Gy fractionated scheme (6 X 2 Gy) might be less effective than the standard 10 Gy single dose TBI for leukemia cell killing and for eradication of the recipient bone marrow. Additional clinical data, ideally coming from well designed randomised trial or from careful large-scale retrospective evaluations, should help to optimize the TBI delivery.