MLC between two HL-A identical siblings and a recombinant

Recombination within the class III region by a double cross over event

Analysis of class I, class II, and class III gene products of the human MHC in a Caucasoid family with four children gave evidence for a double crossing over event in monozygotic twins between the C2, Bf/C4A, C4B gene loci. In view of the small genetic distance between C2 and C4, a point mutation within the Bf locus must be considered alternatively.

Influence of HLA matching and blood-transfusion on outcome of 502 London Transplant Group renal-graft recipients

The outcome of 502 cadaver kidney transplants has been followed for up to six years; these grafts were arranged through the Tissue Immunology Unit of the London Hospital Medical College, the coordinating centre of the London Transplant Group. An analysis of HLA (A and B) recepient-donor matching revealed, as in previous analyses, clear differences (now highly significant) between the best as compared with the lesser matched recipients. A quarter of the patients (group 4 and 3a) had a superior outcome 20-30% greater than poorly matched (2 or less group) which constituted 53% of individuals. The results in the 3b group (28% of patients) were intermediate 10-15% better than the "2 or less antigens in common" group. A small number of recipients mostly 4 or 3 matched who were retrospectively HLA-D matched showed an even better graft survival. The effect of blood-transfusion before transplantation was studied and found to improve the outlook especially in the best-matched groups. No difference was apparent between those receiving less or more than ten units except in a group of patients with cytotoxic antibodies and/or retransplants. This "immunocompetent-presensitised" group had the best outcome provided these recipients had few transfusions and were subsequently well matched. These findings emphasise the continued need for successful collaborative associations, so that improved matching can be achieved which if universally applied would ensure better graft survival for a large number of patients in renal failure.

Ankylosing spondylitis and the major histocompatibility system

The purpose of this investigation was to see whether or not the hypothetical disease susceptibility locus to ankylosing spondylitis is linked to the MLC determinant 27a. Firstly, we discovered a strong MLC determinant which we called 27a because of its association with the second series specificity W27. Later, we found that this determinant was the same as that which Jorgensen et al. (1973) found to be associated with the second series specificity W5. These MLC determinants may, therefore, be in linkage disequilibrium with more than one HL-A specificity (in this case, of the second series) as previously described by Dupont et al. (1973). However, we found no association between 27a and ankylosing spondylitis. On the other hand, we confirmed the association of ankylosing spondylitis with W27 and also found an increase of HL-A2 of the first series which, however, was not statistically significant. In view of the high incidence of HL-A2 in the general population, more information is required to definitely establish such an association. We found no special association with specificities AJ and Hu (Sa 532), third series antigens, but confirmed their linkage disequilibrium with W27. Disease predisposition loci seem, therefore, to be associated with either type of MHS marker, multiple sclerosis and MLC determinant 7a, or ankylosing spondylitis and the second series antigen W27. It will be interesting to discover whether there is any special significance of the association of one marker rather than another.