An HLA-DR/DP recombinant family involving DPw6. Evidence for cross-reactivity between DPw6 and GNN2B

The immunodeficiency of bone marrow-transplanted patients. II. CD8-related suppression by patient lymphocytes of the response of donor lymphocytes to mitogens, antigens, and allogeneic cells

Lymphocytes from 21 patients sampled 1-6 months after bone marrow transplantation (BMT) were tested for functional suppressor activity against marrow-donor lymphocytes in the lymphocyte transformation test. Suppression of donor responses to allogeneic (i.e. mixed lymphocyte reaction, MLR) and antigenic stimulation by irradiated (7600 rad) post-BMT cells was observed in about two-thirds of the combinations tested (N = 20 and N = 9). The suppression of donor MLR and antigen responses ranged between 5-52% and 10-46%, respectively. Irradiated post-BMT cells significantly suppressed donor responses to suboptimal concentrations of phytohaemagglutinin (PHA) (median suppression: 28%; P less than 0.05; N = 7) and concanavalin A (Con A) (median suppression: 31%; P less than 0.05; N = 6). A clearly suppressive effect of post-BMT cells was observed when the ratios of CD4+/CD8+ post-BMT cells were lower than 0.5 (P less than 0.01). In three experiments, the depletion of the CD8- but not of the CD4-positive subset abrogated the suppression of the donor MLR by post-BMT cells. The suppression by post-BMT cells (irradiated) of MLR and mitogen responses was comparable whether the responding cells were derived from the donor or from HLA-DR-incompatible, unrelated individuals. The proliferative capacity of post-BMT cells compared to that of donor cells was assayed in the MLR with unrelated, HLA-DR-incompatible stimulator cells. A significantly decreased proliferative capacity (median 20% of that of donor cells) was found (P less than 0.01; N = 16). A weak inverse correlation (P less than 0.05; N = 16) between the proliferative and the suppressive capacity of post-BMT cells in the MLR was observed. These findings indicate that the decreased proliferative capacity upon mitogen, antigen, and alloantigen stimulation observed in most patients within 1-6 months after BMT may be partly due to non-specific suppression by CD8+ cells.

Restriction fragment length polymorphism of the HLA-DP subregion and correlations to HLA-DP phenotypes

The restriction fragment length polymorphism (RFLP) of the class II HLA-DP subregion of the major histocompatibility complex (MHC) of humans has been unraveled by Southern blotting using DP alpha and DP beta probes in a study of 46 unrelated individuals with known HLA-DP types. Contrary to earlier preliminary findings with a limited number of enzymes, the RFLP appears to be quite extensive both with the DP beta (14 different DNA markers defined by individual fragments or clusters thereof) and the DP alpha (8 markers) probes, especially when enzymes recognizing only four base pairs were used. A few markers were absolutely or strongly associated with individual DP antigens, whereas most were associated with two or more DP antigens as defined by primed lymphocyte typing. Thus, Southern blotting seems feasible for typing for most DP determinants by specific fragments or subtraction between the various more broadly reactive DNA markers, and the RFLP provides further information on the DP subregion in addition to that provided by primed lymphocyte typing. In two recombinant families, the DP beta and DP alpha DNA markers segregated with DP antigens, whereas the DR beta, DQ beta, DQ alpha, and DX alpha markers followed the DR and DQ antigens.

The HLA-DP polymorphism in Denmark investigated by local and international PLT reagents. Definition of two "new" DP antigens

Lymphocytes from highly selected donors were primed for 10 days and subsequently bulk-expanded in IL 2 (TCGF) containing cultures. Two well-discriminatory PLT (CDP = Copenhagen DP) reagents against each of the DPw1-w6 specificities and one against each of the two "new" specificities, CDP4s and CDPHEI, were selected for further studies. Three combinations made in two recombinant families and four of ten HLA-A, B, and DR compatible combinations discriminated well in contrast to seven of 46 DR compatible, but HLA-A or B incompatible combinations. All reagents gave highly reproducible results, and high correlations (r-values between 0.73-1.00) for DP assignments were obtained with CDP and GNN reagents. No triplets were found for the DPw1-w6 and CDP HEI specificities. The "new" specificity CDP HEI defined in an HLA-DR/GLO recombinant family gave a coefficient of correlation with GNN 8 of 0.91. Another "new" specificity, CDP4s constitutes a subgroup ("split") of DPw4. The gene frequencies of DPw1-w6 estimated in 102 unrelated randomly selected Danes agreed with those reported for other Caucasoid populations. The gene frequencies CDP HEI and CDP4s were 0.03 and 0.08, respectively. The associations between DR3-DPw1, DR2-DPw4, and DRw6-DPw2 were confirmed. It is concluded that DP-typing with bulk-expanded reagents is a reliable and so far the only technique which can reveal the polymorphism of the DP gene products.