HLA-AB and -DR types in patients with infectious mononucleosis (IM)

Effects of infectious mononucleosis and HLA-DRB1*15 in multiple sclerosis

BACKGROUND

Both human leukocyte antigen (HLA)-DRB1*15 and Epstein-Barr virus infection presenting as infectious mononucleosis (IM) are recognized as risk factors for multiple sclerosis (MS). However, their combined effect and possible interaction on MS risk is not known.

OBJECTIVE

To assess the association between HLA-DRB1*15 and risk of MS in persons with and without IM.

METHODS

We compared the prevalence of DRB1*15 in MS patients with (n = 76) and without (n = 1,836) IM with the corresponding distributions in blood donors with (n = 62) and without (n = 484) IM histories. This allowed us to estimate the relative risk of MS associated with DRB1*15 in the presence and absence, respectively, of previous IM. We then estimated the interaction between DRB1*15 and IM as the ratio of the two individual odds ratios.

RESULTS

In IM-naïve individuals, DRB1*15 carried a 2.4-fold (95% confidence interval [CI], 2.0-3.0) increased MS risk. In contrast, among persons with IM history, DRB1*15 was associated with a 7.0-fold (95% CI, 3.3-15.4) increased MS risk. Thus, the MS risk conferred by HLA-DRB1*15 was 2.9 (95% CI, 1.3-6.5)-fold stronger in the presence than in the absence of IM. Combined with previous results, this result indicates that DRB1*15-positive persons with a history of IM may be at a 10.0-fold (95% CI, 6.0-17.9) increased risk of MS compared with persons who are DRB1*15 and IM-naïve.

CONCLUSION

DRB1*15 and IM may act in synergy causing MS.

The significance of HLA studies in human-human hybridomas

The technique of human-human (H + H) hybridoma is employed to generate human monoclonal antibodies. However, in contrast to mouse hybridomas, the human counterpart is very difficult to establish. It is still unclear what the precise reasons are for the failure to establish the human-human hybridoma technique as a routine. Analyses of HLA antigens of seven lymphocyte donors and 22 human cell lines generated by the H + H hybridoma technique have demonstrated the importance of the compatibility between human lymphocytes and the lymphoblastoid cell lines. Furthermore, there is a preferential expression of several HLA on human hybridomas (e.g. B51; B15; B18; B35). Screening several unrelated human lymphoblastoid cell lines available demonstrated preferred HLA antigens (A2, A3; A30/31; B5; B18; B15; B35), despite the fact that these lines were derived from subjects of different ethnic origins. It seems that HLA typing of donor lymphocytes and lymphoblastoid cell lines may help to increase the yield of H + H hybridomas.

HLA-DR antigens and the antibody response against Epstein-Barr virus

Antibodies against Epstein-Barr virus (EBV) antigens, i.e. the viral capsid antigen (VCA) and the Epstein-Barr nuclear antigen (EBNA), were determined in two independent populations with known HLA-DR phenotypes. The first population consisted of 151 patients with rheumatoid arthritis; the second one of 88 healthy parents of leukemic children. Although the group of patients with rheumatoid arthritis differed significantly in the frequency of 4 DR antigens from the second group, both groups had the same correlation between HLA-DR antigens and the antibody response to EBV antigens. There was a significant correlation between HLA-DR1 and reduced titers of antibodies to VCA, whereas the persons with only one identifiable DR antigen had higher anti-VCA titers. The persons with HLA-DR5 had significantly higher anti-EBNA titers than those without DR5.