Molecular analysis of HLA class II antigens in bone marrow transplanted thalassemic patients

BACKGROUND

In this work we investigated whether serologically HLA class II compatible donor-recipient pairs showed differences in restriction fragment length patterns, and whether there is a correlation between the genomic differences observed and the incidence of rejection and acute graft versus host disease (GVHD).

METHODS

High molecular weight DNA was extracted from thirty-three transplanted thalassemic patients and from their genotypically HLA identical donors. The DNA was digested with TaqI and PstI restriction enzymes, separated by horizontal electrophoresis and transferred onto nylon filters.

RESULTS

Differences at the molecular level were observed in only one patient, who rejected the transplant respect to his donor when DNA was digested with the TaqI restriction enzyme and hybridized with DPB cDNA probe.

CONCLUSIONS

Although the molecular analysis revealed a difference between a patient who rejected the transplant and his donor, the RFLP typing confirmed the serological identity of the HLA class II antigens in all the other donor-recipient pairs studied.

HLA compatibility for patients with thalassemia: implications for bone marrow transplantation

In order to evaluate the possibility of a patient with thalassemia finding an HLA-identical sibling donor, we performed an analysis of HLA antigens in families of thalassemic patients. The pattern distribution was not significantly different from the expected ratio 25:50:25. When the siblings were subdivided according to the age of the patients (under or over 5 years), the above pattern remained unmodified for both the age groups. The average size of the 129 thalassemic families was 2.4. Thus, taking into account that thalassemic patients have an average of 1.4 siblings and that the HLA genotype distribution is expected as such, HLA-matched siblings are available for 33% of the patients. Because an additional 8.5% of the patients were found HLA-phenotypically identical to one parent, the chance for a patient with thalassemia to find a suitable donor for bone marrow transplantation would be increased to 41.5%. Our preliminary data cannot be extrapolated to the overall Italian thalassemic population; however, it can be inferred that for a patient with thalassemia, the chance of finding a suitable donor for bone marrow transplantation is not reduced.

An attempt to obtain a specific antiserum for in vitro immunological conditioning of bone marrow in acute non-lymphoblastic leukemia

An antiserum was produced in rabbits to acute undifferentiated leukemia (AUL) antigens. Partial absorption of the antiserum allowed the removal of the cytotoxic activity against normal mononuclear cells of peripheral blood and bone marrow, in contrast to blast cells from acute and chronic leukemias, which were killed by the antiserum in a standard NIH cytotoxicity test. These observations suggest that antigens present on blast cells of AUL are also expressed on some acute and chronic leukemic cells and that these antigens could be interpreted as B or leukemia-associated antigens because of the disappearance of all cytotoxic activity of the immune serum after extensive absorption with B cells from chronic lymphoid leukemia.