HLA Antigens, Blood Groups and Immunoglobulin Levels in Idiopathic Thrombocytopenic Purpura

Abstract

Thirty-three patients with idiopathic thrombocytopenic purpura (ITP) were tested for HLA-A, B and C antigens, platelet antibodies, immunoglobulin levels and ABO blood groups. With one exception, ITP proved not to be significantly associated with the HLA antigens studied; an increased frequency of HLA-A28 was found in chronic ITP patients (50 vs. 18.7% in the control population). An increased incidence of blood group A was found in ITP patients (64 vs. 37.98% in the control population), especially in those with acute ITP (84.7%). A significant reduction of IgG levels was noted in patients with chronic ITP, while below-normal levels of IgA were found in both chronic and acute ITP patients. There was no difference in levels of IgM. Circulating platelet isoantibodies were demonstrated in 67.6% of the ITP patients. No correlation was demonstrated between the presence of platelet antibodies, immunoglobulin levels or HLA antigens.

Predisposition to idiopathic thrombocytopenic purpura maps close to the major histocompatibility complex class I chain-related gene A

“…Indeed, single associations of HLA-B8, -B12 [8], and -A28 [9] with ITP have been described; moreover, HLA-A3/B7/DR2 and HLA-A26/ B38/DR2 haplotypes, which are discrepant in their class I components, were also found to be associated with ITP [10]. On the other hand, further studies have not confirmed any class I association with ITP [30 -33], and different MHC class II alleles, HLADRB1*0410 and HLADRB1*0101, were associated with the disease in distinct studies [5,6].…”

“…Genetic factors can influence the development of autoimmune diseases, especially immune-response genes, including the human leukocyte antigen (HLA) genes. Indeed, some association studies have indicated genetic polymorphisms on HLA genes as predisposing factors to ITP [5][6][7][8][9][10]. However, the associations reported were generally weak and varied among the studies.…”

Genetic studies in pediatric ITP: outlook, feasibility, and requirements

“… a synonymous: BLYS, CD257, TALL-1, TALL1, THANK, TNFSF20 b aITP= acute ITP, cITP= chronic ITP c not reported in more detail d other HLA typing studies (33–36) have discrepant results and used the non-genetic two-stage microlymphocytotoxicity test according to the NIH Tissue Typing Manual. Therefore these reports are not reported in this table.…”

MHC Class I–Associated Peptides Identified From Normal Platelets and From Individuals With Idiopathic Thrombocytopenic Purpura

“…HLA alleles found to be associated with ITP include HLA-B8 and -B12 in adult patients with chronic ITP [11], Aw32 in children with acute ITP [12], and HLA-A28 in chronic ITP patients [13]. The presence of HLA-DRw2 was also significantly increased in ITP patients along with the co-occurrence of either A3 and B7 (known to be in linkage disequilibrium with DRw2) or A26 and Bw38 [14].…”

“…HLA studies that associated ITP with a particular HLA allele can potentially be explained by sampling error from heterogeneity of the population, regional differences in HLA frequency, different diagnostic criteria for ITP that accounts for the HLA association, or linkage disequilibrium [13,15,22]. In addition, most of the studies were done 20 -30 years ago when HLA antisera and HLA alleles were not as well defined.…”