Effect of myasthenia serum and antiacetylcholine receptor monoclonal antibody on the distributions of T-cell subsets in myasthenia patients and normal subjects

The distribution of OKT4⁺ helper and OKT8⁺ suppressor T-cells was studied in 41 myasthenia gravis (MG) patients and 20 normal subjects. When a purified T-cell population was studied, the mean percentage of OKT4⁺ cells of MG patients was slightly lower than that of normal subjects (41.6 ± 3.9% vs 43.5 ± 4.7%, p = 0.04); the mean percentage of OKT8⁺ cells in the former was much lower when compared with that in the latter (29.2 ± 4.5% vs 33.8 ± 6.2%, P < 0.001), resulting in a significantly higher ratio of OKT4⁺/OKT8⁺ cells in MG patients (1.45 ± 0.22% vs 1.32 ± 0.20%, p < 0.02). Neither the age of onset of disease nor sex had any effect on the distribution of T-cell subsets. The mean percentages of OKT4⁺ and OKT8⁺ cells of MG patients and normal subjects were decreased after incubation with MG sera, although only the decrease in OKT4⁺ cells reached a statistically significant level, but no such phenomenon was noted after incubation with normal sera. Furthermore, the percentages of OKT4⁺ and OKT8⁺ cells of normal subjects were also decreased after incubation with an anti-acetylcholine receptor (AChR) monoclonal antibody, BK73G. It is therefore concluded that the presence of anti-AChR antibody may account for the immunoregulatory aberration manifested by the loss of suppressor T-cells and the increased helper/suppressor cell ratio in MG patients.