Factors influencing circulating OKT8 cell phenotypes in patients with multiple sclerosis.

Peripheral blood OKT8 cell phenotypes were correlated with measurements of plasma cortisol and serological evidence for exposure to 15 infectious agents, in longitudinal studies involving 13 patients with multiple sclerosis, 13 of their siblings, nine spouses and 13 unrelated controls; 44/48 individuals were HLA typed. Neither circadian rhythms, nor exposure to any one infectious agent accounted for the serial changes in OKT8 cells but there was an association between the presence of HLA-DR2 and periodic reductions in OKT8 cells irrespective of clinical status. Taken with previously reported serial observations in patients and cohabiting relatives, this finding provides indirect evidence for an interplay between environmental and genetic factors in determining OKT8 cell phenotypes in multiple sclerosis.