HLA, autoimmunity, and rheumatic heart disease. Apparent or real associations?

The role of HLA molecules in susceptibility to chronic rheumatic heart disease

Only a small fraction of the streptococcal pharyngitis progress to rheumatic carditis, which implies that environmental, host and microbial factors interact to cause an aberrant immune response against the antigens of the microorganism that cross-react with cardiac tissues. Although there are numerous studies and a general consensus on the relation between human leucocyte antigen (HLA) class II antigens and rheumatic heart disease (RHD), the details and the culprit antigens are still controversial. The study was undertaken to examine 100 patients with chronic RHD and 100 controls for HLA class I and class II antigens for differences in prevalence. All samples were typed at the HLA-DRB1/3/4/5 and DQB1 loci by the sequence-specific primer (PCR-SSP) method at low resolution. For HLA class I antigens, HLA-B13 frequency was marginally increased in patients with RHD compared to controls without reaching statistical significance. For class II antigens, RHD patients had higher frequencies for HLA-DRB1*01 (RHD 24%, controls 10%), DRB1*04 (RHD 35%, controls 26%), DRB1*07 (RHD 18%, controls 11%) and HLA-DQB1*02 (RHD 32%, controls 17%) without reaching statistical significance, and significantly lower frequencies for DRB1*13 (Pc < 0.003, OR: 5.69), DRB5* (Pc < 0.003, OR: 33) and DRB3* (Pc = 0.03, OR: 2.66) compared to controls. It was concluded that host, microbial and environmental factors collude to create acute rheumatic fever (RF) and chronic rheumatic valve disease. The HLA-DRB1*13, DRB5* and DRB3* were protective against the development of rheumatic valve damage.

Poststreptococcal reactive arthritis: clinical characteristics and association with HLA-DR alleles

OBJECTIVE

To assess the relationship of poststreptococcal reactive arthritis (ReA) to other forms of ReA and rheumatic fever by comparing the frequency of HLA-B27 and DRB1 alleles in these diseases.

METHODS

The diagnosis of poststreptococcal ReA was established in 25 children seen in a pediatric rheumatology clinic. HLA-B27 and DRB1 genotyping was performed in 18 of the white American patients. The DRB1 genotyping results were compared with those in 33 patients with rheumatic fever and 190 normal individuals.

RESULTS

HLA-B27 was positive in 3 of the 18 poststreptococcal ReA patients, a frequency not different from that found in normal individuals. Compared with normal controls, the frequency of the DRB1*01 allele was higher in poststreptococcal ReA patients (odds ratio [OR] 2.7, P=0.044), while DRB1*16 was increased in patients with rheumatic fever (OR 4.3, P=0.028).

CONCLUSION

The association of poststreptococcal ReA with HLA-DRB1*01, but not with HLA-B27, suggests that its pathogenesis may be more similar to that of rheumatic fever than to that of ReA associated with enteric pathogens.

Major histocompatibility complex class II gene frequencies by serologic and deoxyribonucleic acid genomic typing in idiopathic dilated cardiomyopathy

Certain immunologic features associated with idiopathic dilated cardiomyopathy (IDC) suggest an infectious and/or autoimmune etiology. In this regard, an association between the major histocompatibility complex class II allele, DR4, and increased risk for IDC was previously identified. In the present report, 43 additional patients with IDC and 236 control subjects were studied for major histocompatibility class II allele associations. DR alleles were identified by microcytotoxicity. No significant differences between control subjects and patients with IDC were seen, although the frequency of DR4 was increased among patients. DR4 subtyping (n = 9) was performed by "dot blot" hybridization of allele-specific oligonucleotide probes to PCR-amplified genomic deoxyribonucleic acid. The DRB1*0401 and DRB1*0404 alleles were each found in 44% (n = 4) of patients with IDC, and DRB1*0407 was identified in 1 patient (11%). DQ and DP alleles were identified by restriction endonuclease codigestion of polymerase chain reaction-amplified deoxyribonucleic acid. The digested fragments were separated and identified by polyacrylamide gel electrophoresis. Differences between patients and control subjects were observed for DQA1*0501 (11% of patients vs 28% of control subjects, p < 0.05) and DQB1*0201 (13% patients vs 25% control subjects, p < 0.05). A modest difference was noted for DQA1*0301 (35% patients vs 23% control subjects, p = 0.08). These findings suggest a complex immune-related etiology for IDC that cannot be explained solely by the presence or absence of a single class II allele. However, this and other studies continue to implicate genes within the class II region in determining the risk for IDC.