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The existing estimates of the recombination fraction between DR and DP are quite variable and often based on anecdotal observations. We have estimated the DR/DP crossover frequency on the basis of families typed for HLA markers and GLD. The frequency of DR/GLO crossing over was 8.7% (23/264 informative meioses), maternal recombinations being about twice as frequent as paternal ones. Of 17 DR/GLO recombinant families typed for DPwl-6, DP was informative in 11 (13 recombinations) but only one of these gave rise to a DR/DP crossover. According to these data the DR/DP recombination fraction is below I%, in contrast to some earlier published materials. HLA-DR/DP haplotypic associations on 127 informative Caucasoid haplotypes have been evaluated. In agreement with previous studies, DR3 was positively associated with DPwl and, in addition, DR7 was found to be positively associated with DP-blank (not DPwl-6). The rare DPw6 allele is possibly associated with the DR4, Dw14 allele. The DR-DP haplotype profiles suggest other associations which might become significant if larger materials are tested. The frequency of DP alleles in a random material (N = 201) was found to be in accordance with most of the previously published frequences on European Cauca-soids with DPw4 as the predominating frequency (gene frequency 40%) and a blank frequency of 21%.

Recent multicenter, randomized clinical trials have shown that in renal transplant patients tacrolimus (FK506) was more efficient than cyclosporine A (CsA) at preventing acute rejection. In order to try and evaluate whether this difference was related to a different in vivo T-cell suppression we assessed, in a prospective study, the frequencies of interleukin (IL)-2-, IL-4-, IL-5-, IL-6-, IL-10-, interferon-gamma (IFN-gamma)- and double-positive IL-2/IFN-gamma-producing whole T cells, CD4 + and CD8 + T-cell subsets by means of cytokine flow cytometry. This was performed after in vitro stimulation of peripheral blood mononuclear cells (PBMCs) with phorbol myristate acetate (PMA) and ionomycin, in the presence of monensin, in 14 healthy volunteers (controls) and in 14 renal transplant patients. The immunosuppression of the latter was based either on CsA (n = 7) or on FK506 (n = 7). Cytokine-expressing T-cell frequencies were assessed immediately pretransplantation (DO), and subsequently 3 months (M3) and 6 months (M6) afterwards in fasting patients prior to the morning intake of the immunosuppressive drug. We found that at DO the frequencies of IL-2-(22 +/- 2% vs. 22.2 +/- 2%), IFN-gamma-(26 +/- 3% vs. 29 + 3.4%) and IL-4-(0.8 +/- 0.2% vs. 1.4 +/- 0.2%)-expressing T lymphocytes were not significantly different between the controls and the patients, respectively. Conversely, the frequency of IL-2/IFN-gamma double positive cells was higher in the latter (9.3 +/- 1.6%) than in the controls (5.6 +/- 0.8); p = 0.06. Finally, on D0 the frequencies of IL-5-, IL-6-, and IL-10-producing T lymphocytes were lower than 1%, in both groups, as well as after grafting, i.e. on M3 and M6. As compared to baseline (DO): (a) chronic immunosuppression significantly decreased the frequencies of IL-2-, IL-4- and IL-2/IFN-gamma-expressing T cells, whereas those of IFN-gamma, IL-5, IL-6, and IL-10 were not significantly affected; (b) the frequencies of cytokine-expressing T cells were not statistically different between M3 and M6; (c) the decrease in the frequencies of IL-2- and IL-2/IFN-gamma-expressing T cells affected CD4 + and CD8 + cells equally; (d) there was a marginal decrease in the frequency of IFN-gamma-expressing cells only in the CD4 + subset but not in the CD8 population; and (e) for CsA, but not for FK506, the frequency of the IL-2-expressing T cells was negatively correlated with the whole blood trough levels. When we compared the frequencies of cytokine-expressing cells in FK506- and CsA-treated patients, we found that the frequency of IL-2-expressing T cells was significantly lower with FK506 (10.9+/-1.61%) than with CsA (16.3 +/- 1.8%; p = 0.03), whereas the frequencies of the other cytokine-expressing cells were not statistically different between the two groups. In conclusion, our study clearly demonstrated that studied ex vivo, FK506 and CsA decrease the frequencies of cells expressing IL-2, IL-4 and IL-2/IFN-gamma in vivo but do not affect those expressing IFN-gamma. Meanwhile, the frequency of IL-2-producing T cells was more affected with FK506 than with CsA and was negatively correlated with the CsA trough level. Finally, our results regarding IL-2 might explain to some extent the higher efficiency of FK506 in vivo than CsA.

We confirm here the CD43 specificity of the CBF.78 monoclonal antibody (mAb) and compare its phenotypic and functional capacities to classical group-A mAbs (DFT1, MEM-59) and to 2 other CD43 mAbs (RDP/AD9, 161-46). It reacts with stable human CD43 transfectants in a sialic acid independent way and blocks completely cell binding of RDP/AD9 or 161-46 more or less but not DFT1 and MEM-59. Its distribution differs from all other CD43. B lymphocytes, but surprisingly the majority of granulocytes or monocytes are CBF.78 negative. CBF.78 is expressed on all T lymphocytes, but the number of CBF.78 molecules/cell is low and equally represented on resting T CD4 and CD8 cells. In comparison to naive T lymphocytes, CD45RO cells increase their CBF.78 epitopes much more than other CD43 epitopes. At a single cell level, confocal microscopy shows that CBF.78 can exist independently of other epitopes. CBF.78 is able to induce homotypic adhesion in different cell lines but not in peripheral blood lymphocytes and is unable to relocalise the targeted molecules. U937 cell line that is not agglutinated by CBF.78 (or RDP/AD9) undergoes a stronger adhesion with PMA, when this reagent is combined with this mAb. By itself CBF.78 is unable to activate T lymphocytes and to costimulate CD3 mAbs but partially blocks PMA. The phosphorylation of the tyrosine kinase p59fyn and p56lck, driven by CBF.78, is weak and almost blocked by PMA. Altogether these data support the hypothesis that there are at least 3 modes of interaction between PKC and CD43 pathways: each pathway is inhibitory towards the other but the CD43 one can also be synergistic.

The Basques were previously shown to present a high frequency of HLA-B18 and BfF1, which are known to be associated with insulin dependent diabetes mellitus (IDDM). During the VIII International Histocompatibility Workshop, we studied HLA-A, B, C, DR; Bf, C4 and GLO.I polymorphisms in 51 unrelated French Basque IDDM patients and in 50 controls. Haplotypes were established by family studies in all controls and some patients. Two haplotypes were frequently found in the controls: HLA-A1, Bw57, BfS, C4 F1S, DR7 and HLA-Aw30, Cw5, B18, Bf F1, C4Fs degree, DR3. The first one was not found in the patients. All the components of the second haplotype had increased frequencies possibly as a consequence of linkage disequilibrium with HLA-DR3: a highly significant association between IDDM and HLA-DR3 was observed (90.2% vs 24.0%, relative risk (RR) = 29.1, P less than 10(-11)). The HLA-DR4 frequency was slightly increased (37.3% vs 16.0%), and HLA-DR2 was not found. The silent allele C4s degree was particularly associated with early diagnosed IDDM (86.7% in patients with age at onset under 20 years vs 57.1% in other patients, P less than 0.02). The high relative risk for HLA-DR3/DR4 heterozygous vs that of individuals, possibly HLA-DR3 homozygous, supported the hypothesis that two HLA-DR linked genetic factors could be involved in the inheritance of IDDM susceptibility.

In the genetically homogeneous Danish population, 27 HLA-DR3,4 heterozygous patients with insulin-dependent diabetes mellitus (IDDM) and 19 DR3,4 heterozygous controls without family history of IDDM were investigated for HLA-region markers and Gm and Km immunoglobulin allotypes. The aim was to define susceptibility factors for IDDM development other than HLA-DR using a number of techniques: lymphocytotoxicity (HLA-DR and DQ antigens), cellular methods (Dw and DP typing), restriction fragment length polymorphism (DQ alleles), electrophoresis and immunofixation (BF and C4 allotypes), and passive hemagglutination inhibition (Gm and Km immunoglobulin allotypes). The complement allotype C4A3 and the HLA-DQw8 (DQw3.2) antigen were found in all of the patients, whereas this was the case for only 8 of the 19 controls (P=6 x 10−6): five lacked C4A3, five others lacked DQw8, and one of the controls lacked both of these factors. Fourteen of the patients had the complement allotype C4B3 versus three of the controls (P=0.01). Previously reported family studies suggest that these alleles are part of the following haplotype: B15, BFS, C4A3, C4B3, DR4, Dw4, DQw8, and these factors were found together in ten of the patients versus one of the controls (P=0.01). The markers usually associated with DR3 did not show significant differences between IDDM patients and controls, and the non-HLA markers studied showed no significant deviation from what was expected. In addition to the susceptibility factor DQw8, the study suggests the existence of susceptibility genes for IDDM near the complement C4 genes on DR4-carrying haplotypes. Since recent works have shown that the structural gene for the monokine tumor necrosis factor alpha (TNF-α) is located between the HLA-B and C4 loci and that TNF-α might be of importance in IDDM pathogenesis, the hypothesis is put forward that the C4-associated IDDM susceptibility reflects linkage dis-equilibrium between the C4 gene and a gene controlling TNF-α production. The high relative risk for IDDM in HLA-DR3,4 heterozygotes might be explained by the combined action of IDDM-specific susceptibility genes on DR4 haplotypes and DR3-linked susceptibility genes associated with predisposition to autoimmunity.

We report the study of a serum from a polytransfused patient, that contains an anti-HL-A8 antibody reacting by the platelet complement fixation microtechnique. The specificity is confirmed by a study on a panel of 112 different platelets and by experiments of absorption-elution on platelets, lymphocytes and granulocytes.

Summary We studied 201 unrelated French Basque individuals for HLA and Bf polymorphisms. The haplotypes of eighty-seven of them were deduced from family studies. The results show the frequency of the Bf F1 allele (0.1393) which is the highest one currently reported. They confirm the high frequencies of HLA-Aw19.2 and B18 previously reported in that population and show that a whole haplotype with strong linkage disequilibria, namely Aw19.2, Cw5, B18, Bf F1, DRw3 is frequent. On the other hand, the gene frequency of Bf S is decreased (0.5497) as compared with the other European Caucasoid populations, while a slight increase in the Bf F gene frequency (0.2960) appears. These results point out that it is of importance to consider the genetic background in choosing the population where linkage disequilibria are to be studied.

Since 1980, a DR blank specificity undefined by serology but known to segregate in families linked to DQw1 has been recognized. We describe a Caucasoid family, BON... where 4 among 8 children are homozygous for such a specificity; their cells can be used as homozygous typing cells and the specificity defined is provisionally called D-BON. There is no known consanguinity in this family. The homozygous D-BON cells carry DR molecules as shown by their reactivity with monomorphic anti-DR monoclonal antibodies. In a random family material consisting of 210 haplotypes, the gene frequency of D-BON is between 1 and 2%, which corresponds to about 40% of the DR blank frequency. The D-BON specificity seems associated with DQw1 and also with B35 and C4B2.

In 45 patients who received kidney transplants, both homologous and heterologous human antiglobulins (anti-Ig) and HLA cytotoxic antibodies have been studied before and after transplantation and in some cases after nephrectomy. A similar study has been performed in a control group of 1,019 healthy blood donors and in 130 patients with acute or chronic glomerulonephritis. After transplantation, homologous anti-IgG were found in 60% of the patients, as compared with 3.5% in the healthy blood donors and 21% in patients with various forms of glomerulonephritis. This difference is particularly striking in sera obtained prior to nephrectomy; the presence of anti-IgG and cytotoxic antibodies in the same patient being significantly associated with early transplant failure. Anti-IgA were found in 75% of the patients with transplants and in 37% of the patients with glomerulonephritis. There was no relationship between the anti-IgA and the outcome of the graft. On the other hand, heterologous anti-Ig were unchanged in the three groups investigated. The mechanism of formation of the anti-IgG is not clear. They are probably antibodies against antigenic structures of the patient's own antibodies, previously combined with a soluble antigen or an antigen on the transplant that has undergone molecular transformation in the course of this reaction. Their pathogenic role, although not demonstrated, can be strongly suspected, and, in a practical way, screening for the anti-Ig in kidney transplant recipients could be of value as a prognostic test.

In a French family with 2 parents and 5 children a crossing over was found in the HLA region on both of the parental haplotypes of one of the children. The following markers were studied: HLA-A, B, C,DR, DQ(MB), DP(SB), complement allotypes C4 and Bf and glyoxalase I polymorphism. In the third child, the paternal haplotype had a recombination between HLA-A and HLA-C and the maternal haplotype a recombination between HLA-B and complement locus C4. Mixed lymphocyte cultures confirmed the serological findings and non-HLA markers (blood groups and immunoglobulin allotypes) showed no evidence of extrapaternity. The family also demonstrates a probable duplication of the C4B1 gene in one of the paternal haplotypes.