Lymphocyte abnormalities in ankylosing spondylitis.

Peripheral blood T (SRBC rosette) and B (AgG- and C-receptor) lymphocyte subpopulations and responsiveness to phytohaemagglutinin (PHA) were assayed in 40 patients with ankylosing spondylitis and in 55 normal subjects. There was no significant difference in the lymphocyte concentrations or responsiveness to PHA between the two groups. However, the percentages of T lymphocytes were significantly lower in the patients irrespective of their HLA typing. This was probably due to an increase in the 'null' population since the percentages of both the AgG- and C-receptor cells were normal.