Effect of oral colchicine on T cell subsets, monocytes and concanavalin A‐induced suppressor cell function in asthmatic patients

Asthmatic patients have a deficiency of concanavalin A‐(Con A) induced suppressor cell function. We tested whether oral colchicine 0·5 mg twice daily for 7 days could correct this immunoregulatory abnormality. Peripheral blood mononuclear cells were incubated with Con A and then suppression of proliferation was measured by co‐culture of these cells with healthy volunteers’mononuclear cells and phytohaemagglutinin. Sixteen asthmatic patients had significantly (P < 0·002) decreased Con A‐induced suppressor cell function (17·0±17·2%, mean ± s.d.) as compared to 13 healthy volunteers (37·9±14·9%). Oral colchicine significantly (P < 0·05) increased, though only partially corrected, these 16 asthmatic patients’Con A‐induced suppressor cell function (28·1±14·3%). Asthmatic patients had an increased number of monocytes (691±289 vs 388±271/mm³ for normals, P < 0·01) and a normal number of lymphocytes, Leu 4+ total T cells, Leu 3+ helper/inducer T cells, and Leu 2+ suppressor/cytotoxic T cells as well as a normal Leu 3/Leu 2 ratio. Oral colchicine significantly (P < 0·005) decreased the number of monocytes (451±255/mm³) without significantly affecting the number of lymphocytes, Leu 4+, Leu 3+, or Leu 2+ T cells, or the Leu 3/Leu 2 ratio. These results are consistent with the hypothesis that the deficiency of Con A‐induced suppressor cell function in asthmatic patients may be due, in part, to an increased number and/or abnormal activity of monocytes. If so, then oral colchicine may have partially corrected the deficiency of Con A‐induced suppressor cell function by decreasing the number and/or modulating the activity of monocytes.