The HLA class I-CML association revisited taking into account the two forms of gene fusion in the Philadelphia chromosome. A multicenter study.

CML patients possess either a b3-a2 or a b2-a2 fusion between the BCR and ABL genes. Depending on the type of fusion, two different series of non-self potentially immunogenic peptides may be produced. If they are presented by HLA class I molecules and recognized by cytotoxic CD8 lymphocytes, individuals could be more susceptible or resistant to leukemic cells bearing one or the other form of fusion according to their HLA class I phenotype. To test this point, the frequencies of HLA-A and HLA-B alleles were compared between b3-a2 and the b2-a2 CML patients. In essence, no difference was found whose significance could withstand correction for multiple comparisons.

Serum levels of beta-2-microglobulin-free heavy chain of HLA class I antigen in healthy individuals: relationship to their class I allotype.

An ELISA-based double determinant immunoassay has been established to measure the soluble beta2-microglobulin (beta2m)-free heavy chain (FHC) of the HLA-B, -C (and HLA-A3, -A28 and -A30) class I molecular complex in sera from 212 HLA-typed healthy unrelated individuals. FHC was calculated by means of a standard curve constructed using serial concentrations of beta2m-associated HLA-class I heavy chain (HLA-I)/FHC purified from cultured human lymphoid cell C1R-sB7-supernatant. The mean FHC concentration (+/-SD) was 0.25 mg/l (+/-0.2). Its median concentration did not statistically differ between males and females, though the male/female ratio was greater in the high secretor (FHC >0.45 mg/l; mean + 1SD) than in the low secretor group (FHC < 0.05 mg/l; mean - 1SD). FHC < 0.05 mg/l was statistically (Fisher's exact test) associated with HLA-B17 (p = 0.003); FHC > 0.45 mg/l was statistically associated with HLA-B35 (p = 0.003) and -Cw4 (p = 0.002). None of these allele-positive groups showed a mean FHC concentration 1.5 times higher than that of the corresponding allele-negative ones. This allotype-dependent HLA-B and C FHC enhancement was less marked than that previously reported for HLA-I in individuals carrying HLA-A9 (and its splits). These results indicate that FHC could be a more valuable marker when its levels are compared among individuals carrying different allotypes. Moreover the lack of correlation between FHC and HLA-I levels measured in 52 HLA-A3, -A28 or -A30 positive individuals suggests that the two molecules may be regulated by different metabolic pathways and their serum expression may have a different biological significance.

In vitro inhibition of rat serum complement activity by an extract of lyophilised human dura mater.

The inhibiting effects of an extract of lyophilised human dura mater on the complement activity of rat serum have been studied in order to evaluate a possible species-specific antigenic activity in this material generally used in the repair of dural defects. The results demonstrated that the extract may inhibit complement activity of rat serum. The phenomenon resulted to be of low entity (nearly 20% of mean value) and was due to the interaction between tissue species-specific antigens and natural antibodies of rat serum. The residual antigenic activity may limit the use of this material only in xenogeneic graft recipients.

Rare phenotype and transplantability in cadaveric kidney transplant.

The waiting list for kidney transplants in the Apulia region contains recipients (about 30%) who were never selected for transplant due to the rare HLA antigen phenotypes and homozygosis. Therefore, an algorithm was selected to equilibrate the chance for patients to be selected despite a rare phenotype. We calculated for each patient, the sum (%) of the A, B, DR antigen frequency (total phenotypic frequency; TPF). All the potential recipients were grouped into five classes in increasing order of TPF. The number transplanted depended on the phenotype frequency. The selection index was the quotient of the number selected and the total number of patients. The selection index was 0.28 to 0.43 to 0.79 to 1.34 to 2.38 from class 1 to 5. To equilibrate the transplantability of rare phenotype recipients on the waiting list, a bonus was introduced for the most disadvantageous frequency class. Adding the bonus modified the selection index as follows: 1.0 to 1.25 to 1.5 to 1.34 to 2.38, which appears more equilibrated except for the class 5. In conclusion, if a bonus is applied for rare phenotypes, the chance to be transplanted becomes similar between patients with other parameters the same.

[Immunological monitoring after renal transplantation from living donors]. / Monitoraggio immunologico dopo trapianto renale da donatore vivente.

Monitoring of immune responses were done in kidney recipients from living donors using the following assays: CH-50, alternative pathway of complement activation, circulating Ag-Ab complexes, cytotoxic antibodies. All patients had survived 3 to 5 years from transplant. While some alternations (fall of CH-50, cytotoxic antibodies, circulating Ag-Ab complexes) occurred after the episodes of chronic rejection in 2 patients, despite a well functioning allograft, the inhibition of alternative pathway of complement activation demonstrated a coincidental capability to predict rejection episodes. The blocking mechanism of the alternative pathway of complement activation during rejection is not fully understood. The enhancing role of B-lymphocyte antibodies and the function of circulating immunecomplexes were also discussed.

[Cross test with B-lymphocytes in transplantation immunology]. / La prova crociata con i B-linfociti nell'immunità da trapianto.

Cross-matching procedure with B-lymphocytes may facilitate the detection of cytotoxic antibodies. This finding suggested a reliable use of the test in immune monitoring after kidney allograft from living donor. The possible enhancing role of B-lymphocyte antibodies was also discussed.

Description of a new HLA-DRB1*1104, DRB1*110403.

We report here the exon 2 sequence of the novel HLA-DRB1*110403 which differs from DRB1*110401 by a single synonymous nucleotide substitution at codon 78, where TAC is substituted by TAT. The variant originally identified in a Caucasoid individual was confirmed by cloning and sequencing.

Cytotoxic assays of sera of tumor-bearing patients and inhibition of monocyte and granulocyte spreading activities.

Sera of patients with solid tumors showed cytotoxic antibodies against a selected panel of lymphocyte and granulocyte donors, typed for HLA antigens. The same sera were also studied for soluble circulating immune complexes and for the capability of inhibiting granulocyte and monocyte spreading. The percentage of rosette forming cells was also measured in the majority of patients. Some alterations of these immunologic parameters were significantly correlated with the presence of granulocytotoxic antibodies. These results suggested that some unknown factors in sera from patients with neoplasms may interfere with host-defence mechanisms, but the role played by cytotoxins needs further clarification.

Cytotoxic antibodies in cancer patients: possibilities of correlation with HLA antigens.

Sera from 250 cancer patients were tested against a panel of lymphocytes donors, randomly selected and typed for HLA antigens. In 69 patients HLA typing was also performed according to standard NIH technique. While 95 sera (38%) were cytotoxic for total lymphocytes, an increased cytotoxicity for B-lymphocytes was shown. The data were analyzed by means of 2 x 2 contingency tables (chi-square and correlation coefficients). In the majority of cases (72 = 76%) the sera were polyspecific or not correlated with HLA. The remaining 23 sera(=24%) showed a clear-cut statistical relationship to defined HLA specificities on population studies; 5 of these sera correlated with single antigens detected on HLA phenotype of the patients. It is concluded that serum cytotoxicity may complicate HLA genetic typing in cancer patients. It was also considered that anti-HLA antibodies might cross-react with virus or tumor-specific antigens in cancer patients.

Lymphocyte and granulocyte cytotoxic antibodies in cancer patients.

Sera from cancer patients showed lymphocyte and granulocyte cytotoxic antibodies. While lymphocytotoxic antibodies correlated with the HLA system, it was not possible to demonstrate any correlation between the granulocytotoxicity and the HLA antigens. The experiments with 2 ME reduction were consistent with the presence of IgM antibodies in the majority of positive sera tested by the lymphocytotoxic method. The discussion concerning the mechanism of formation of these antibodies was only speculative. Some relationships between tumor neoantigens and the MHC were referred, but the role played by cytotoxins in the host-defence mechanism need further clarification.

Evaluation of rosette inhibition test by antisera to hl-a system.

Specific antisera to HL-A antigens may inhibit spontaneous rosette formation by HPL bearing the corresponding antigen. This rosette-inhibiting activity is removed by absorption with lymphocytes carrying the specific antigen. The rosette-inhibition test may be acceptable as a cross-matching procedure for detecting tissue sensitization in the field of transplantation.

Immunogenetic analysis of association between HLA antigens and psoriasis vulgaris: population and family studies.

A significant increase of some HLA antigens (B13, B17) was shown in 122 psoriasis patients, compared to 176 unrelated individuals of the control group. This finding is not completely secondary to an increase in Cw6, supporting the opinion that different loci within the HLA region are responsible for different forms of the disease. Some familial cases of psoriasis suggest a possible involvement of Bw35, despite the fact that the increase of this antigen in a random population was not significant for the corrected value. In this case it seems likely that a gene associated with Bw35 may be responsible for an infectious form of disease. The fact that 32% of our psoriatic patients did not show either B13, B17 or Cw6, indicated that the Is gene could also segregate with an other haplotype. The Is gene is also dominant, with an incomplete penetrance of B17 and Bw35 among relatives.

[Behavior of rosette-forming human lymphocytes in allogeneic cell mixtures]. / Sul comportamento dei linfociti umani formanti rosette e in miscele cellulari allogeniche

Rosetting lymphocytes have been evaluated in allogeneic mixtures of human peripheral lymphoid cells. In these mixtures E-rosettes were inhibited as compared with that of individuals cells not sharing HLA antigens in common. Mixtures of lymphoid cells sharing HLA antigens in common (familiar combinations) were less or not inhibited. The inhibiting effect has been ascribed to shedding of HLA antigens in the allogeneic mixtures, interfering with the binding of sheep erythrocytes to lymphoid cells. These results confirm the existence of a very closely association between antigen receptor and HLA products on the cell surface of T-lymphocytes.

[Circulating immune-complexes in the serum of rabbits subjected to allogenic skin graft]. / Immuno-complessi circolanti nel siero di conigli sottoposti ad innesto allogenico di cute.

Increased levels of circulating immune-complexes were found in rabbits immunized by allogeneic skin graft or sheep erythrocytes. This result was more marked in rabbits submitted to both experimental procedures. This finding suggested that the phenomenon was conditioned by a major efficiency of immune response.

Beta-2 microglobulin-free HLA class I heavy chain (FHC) A3 and/or A30 soluble products contribute only minimally to serum FHC expression.

No monoclonal antibodies (mAbs) are presently available to measure the total amount of beta2-microglobulin-free HLA class I heavy chain (FHC) in sera. The available ELISA-based double determinant immunoassay (DDIA), established to measure FHC, uses two mAbs (TP25.99 and HC-10) that recognize a monomorphic determinant expressed on all HLA-B/C FHC products and a determinant expressed only on some HLA-A FHC products. This restricted reactivity implies that, in addition to HLA-B/C, HLA-A FHC products are also detected in individuals bearing HLA A3 and/or A30 allotypes. The aim of this study was to establish whether such restriction results in the detection of low FHC levels in individuals lacking HLA A3 and/or A30 allospecificities. The FHC mean concentration (+/- SD) in 294 healthy blood/bone marrow donors (HBDs) was 0.24 (+/- 0.2) mg/l. The grouping of HBDs according to their HLA-A FHC product reactivity with one, both or no mAbs did not result in any statistically significant differences (Mann-Whitney test: P > 0.05) between their median FHC concentrations. Since the absence of differences in their FHC levels was not attributable to a difference in the percentage distribution of HLA allotypes associated with high or low HLA-B/C FHC expression, our results indicate that FHC HLA A3 and/or A30 products detected in DDIA by these two mAbs only minimally contribute to FHC serum expression and that the assay is not limited by the failure to detect HLA-A FHC products in A3- and/or A30- individuals.