Twenty-eight patients with myasthenia gravis (MG), five with and 23 without thymoma, and 47 normal controls were typed for serologically defined HLA-A, B, C, and DRw antigens.
It is believed that transplacental transfer of anti-acetylcholine (ACh) receptor antibodies is responsible for neonatal MG; therefore, neonatal MG represents an in vivo assay of the pathogenic potential of anti-ACh receptor antibodies in 2 human individuals.
Part 1, published in this issue, deals with the clinical and genetic features of myasthenia gravis which led to the autoimmune theory of the etiology of this disease.
Thirty seven Chinese adults and 23 children in Hong Kong with myasthenia gravis were tested for HLA-A and -B antigens and acetylcholine receptor (AChR) antibody.
HLA-A, -B, -C and -DR antigen frequencies determined in a group of 73 myasthenia gravis (MG) patients were compared with those of a control group of 205 subjects.
(2) In both diseases, the autoimmune T cells are clonally heterogeneous but recognize only a limited number of epitopes on the autoantigen (acetylcholine receptor in MG; myelin basic protein in EAE).
We have investigated clonal diversity of B or T cells in the thymus of patients with MG by Southern blot experiments using probes specific for immunoglobulin heavy (IgH) and light chain (IgL) genes and for T cell receptor (TCR) beta- and gamma-chain genes.
All PCR-positive cases were seropositive, including 4 cases of tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM) (4/4), and one case each of myasthenia gravis (1/7) and multiple sclerosis (1/8).
Both splits also distinguish each of the two DR3-bearing extended haplotypes (HLA-B8,SCO1,DR3,DQw2,Dw24 and B18,F1C30,DR3,DQw2,Dw25) found associated to several autoimmune diseases as insulin-dependent diabetes mellitus (IDDM), systemic lupus erythematosus (SLE) and myasthenia gravis.
These results indicate that both the DPB1*0201 allele and DR53 play key roles in the disease process of MG in early-onset females, and that the genetic background of Japanese females with early-onset MG is different from that of other patients with MG.