Immunoglobulin subclasses and HLA alleles in immunoglobulin A deficiency.

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The term "IgA Deficiency (IgAD )" should be reserved for the individuals who do not have detectable disorders known to be associated with low IgA levels . IgG subclass deficiency or a lack of the IgG 2 subclass that is specific against polysaccharide antigens , can be seen in many cases .Forty -five patients (27 males and 18 females ; mean age 8 .6 years , range 6 .3 to 12 .8 years ) with IgA deficiency who had been admitted to the Department of Pediatric Immunology in Uludag University School of Medicine , Turkey , were included in this study . Serum immunoglobulin (Ig ) class and IgG subclass levels , and HLA haplotypes were prospectively determined in patients and healthy controls .Of the 45 patients with IgAD , 1 was found to have a low level of IgG in the serum . Serum Ig levels were also examined in the families of 22 patients . Five patients had low -normal levels of IgM , whilst one had low levels of IgA and IgG . The levels of IgG subclasses were assessed in 23 patients . One patient had a low level of IgG 1 ; 2 had low levels of both IgG 2 and IgG 3 , and 11 had low levels of IgG 3 . IgG subclass concentrations were found to be normal in control groups . HLA alleles were tested in 25 patients . An increased prevelence of HLA-A 1 , -B 8 , -B 14 , -DR 1 , -DR 3 , and -DR 7 were previously observed in patients with IgA deficiency . In this study , HLA-A 1 allel was found in 3 patients (12 %), HLA-B 14 in 3 patients (12 %), HLA-DR 1 in 10 patients (40 %), HLA-DR 7 in 4 patients (16 %) and HLA-DR 3 in 1 patient (4 %). HLA-B 8 allel was not found in any patient . Twenty -five children with normal IgA levels have chosen as a control group . They had HLA-DR 1 (36 %), HLA-DR 7 (16 %), HLA-B 8 (8 %), HLA-DR 3 (16 %). HLA-A 1 was not found in any member of our control group .No statistically significant difference in HLA susceptibility alleles was found between patients and healthy controls . Our data suggest that there may be heterogenous HLA distribution patterns in IgA deficiency , or that HLA allel-associated tendency to IgA deficiency may be polygenic .