SUMMARY Three structural forms of C7 have been distinguished by isoelectric focusing. They are the products of three co‐dominantly expressed alleles at an autosomal locus. The C7 locus is close to that for C6, but is not close to the HLA complex.

Graft-versus-host disease is well recognized in bone marrow transplantation, but has only recently been described in solid organ transplantation. Two such cases in liver graft recipients, proven by the demonstration of donor type HLA antigens in the peripheral blood and marrow on tissue typing, are described in this paper. The literature on this subject is reviewed and the treatment discussed. It is postulated that there is an order of risk of development of graft-versus-host disease depending on the amount of viable lymphoid tissue included with the transplanted organ as follows: small bowel greater than heart-lung greater than liver greater than kidney greater than heart. It seems likely that this condition has been substantially underdiagnosed in the past and that greater awareness of the possibility of graft-versus-host disease in solid organ recipients will lead to the recognition of further cases and allow appropriate treatment to be promptly instituted.

Tissue typing was performed on lymphocytes of sixty-two patients with guttate psoriasis, in forty-four of whom this was the first manifestations of the disease. In 84% of cases, the guttate psoriasis was preceded by a clinical infection. A highly significant excess of antigen W17 (HLA-BW17) was found in patients when compared with healthy population. In common with some other studies antigens HL-A13 (HLA-B13), W15 (HLA-BW15) and W21 (HLA-BW21) were found in excess but these became non-significant after correction for the number of antigens studied. 68% of patients who had guttate psoriasis de novo, subsequently developed persistent plaque psoriasis.