Lymphocyte response to IgG in patients with ankylosing spondylitis and their families.

Lymphocyte responsiveness to IgG was measured by an agarose method in nine patients with ankylosing spondylitis (AS), one patient with Reiter's Syndrome (RS), and thirty-six of their family members. Similar studies were also performed in five patients with rheumatoid arthritis (RA) and twenty-nine of their first degree relatives as well as in seven control families (twenty-seven subjects). Lymphocytes from the ten spondylitic patients and twenty-four of thirty-six family members responded in vitro to autologous IgG. Although most of these subjects had the histocompatibility antigen, B27, there was no association between B27 and response to IgG. Four of the five patients with RA and twenty of their twenty-nine first degree relatives responded in vitro to IgG, whereas only six of twenty-seven control family members gave a positive reaction. There was no difference in the incidence of antiglobulins (detected by agglutination tests) in the family members of patients with AS and RA or in control family members. These data indicate that lymphocyte responsiveness to IgG is the only aberrant immune response thus far described which is shared by patients with AS and RA and their family members.