HLA class II polymorphism in Egyptian children with lymphomas.

UNLABELLED: The major histocompatibility complex (MHC) is a set of closely-linked genes encoded on the short arm of chromosome 6. It is important for understanding human immunological diseases, transplantation and in host defense against infection. The membrane proteins are two types; class I MHC proteins and class II MHC proteins. Strong arguments supporting genetic linkage between susceptibility to lymphomas and human leukocyte antigens (HLA)-class II are reported and give a clue about susceptibility or protection from the disease.

AIM: To evaluate the possible changes of HLA class II (DR, DQ) alleles in children with lymphoma.

METHODS: Thirty cases were included in this limited study. Nineteen cases of non Hodgkin's lymphoma (NHL) and eleven patients with Hodgkin's lymphoma (HD). Their ages ranged from 1.5 to 15 years. The control group consisted of 121 unrelated healthy subjects for DRB1 alleles and 59 unrelated healthy subjects for DQB1 alleles (only 59 subjects were typed for both DRB1 and DQB1). All cases in the study were assessed by thorough history taking, physical examination and laboratory investigations that included complete blood count, renal function tests, liver function tests, serum uric acid and HLA typing. Patients and controls were typed for HLA class II DRB1 and DQB1 alleles using INNO-LIPA reverse hybridization line probe assay (Innogenetic, Belgium).

RESULTS: HLA-DRB1 *0403 and *1301 and HLA-DQB1 *0501,* 0201 and *0301 were significantly increased in patients with NHL when compared with control; whereas HLA-DRB1 *1302 and HLA-DQB1 *0502 and *0602 were significantly decreased when compared with control. In patients with HD, HLA-DRB1 *0403 and *1202 and HLA-DQB1 *0604, *0201 and *0203 were significantly increased when compared with control.

CONCLUSIONS: (1) The susceptibility to NHL is related to HLA-DRB1 *0403 and *1301 and HLA-DQB1 *0501,* 0201 and *0301. (2) The susceptibility to HD is related to HLA-DRB1 *0403 and *1202 and HLA-DQB1 *0604, *0201 and *0203. (3) HLA-DRB1 *1302 and HLA-DQB1 *0502 and *0602 may confer protection to NHL. (4) Different HLA alleles may have a role in patients with both groups of lymphoma and further study is needed to better define the possible prognostic value of different HLA associations in patients with lymphomas regarding increased risk in the presence of certain HLA alleles and the possibility for treatment modifications in the future based on the presence or absence of certain HLA alleles.