Immune status in Crohn's disease. 3. Peripheral blood B lymphocytes, enumerated by means of F(ab)2-antibody fragments, Null and T lymphocytes.

In the peripheral blood of patients with Crohn's disease (CD) the numerical distribution of the three major B lymphocyte subsets was determined by the identification of surface immunoglobulins using F(ab)(2)-antibody fragments. T cell counts were also obtained and the number of null cells was calculated. Twenty-eight patients with Crohn's disease including 14 patients with previously untreated and very short-standing disease (group CD 1) and 14 patients with long-standing and/or previous drug treated disease (group CD 2) were compared with 28 sex and age-matched normals as well as with 13 patients with acute inflammatory bowel disease (group D). Patients in group D and inactive patients of group CD 1 showed a significant absolute lymphocytosis due to an increase in both the three B cell subsets and the T cells, without changes in the null cells. While the proportion of T cells was normal, there was a significant relative B lymphocytosis and a relative null cytopenia in these patients. Active CD 1 patients, however, showed significantly lower absolute lymphocyte and T cell numbers. In group CD 2, there was a significant absolute lymphopenia caused by an equal decrease in B and T cells. Highly active CD 2 patients showed higher absolute null cell counts than inactive patients. With increasing disease duration there was a significant decrease of the relative and absolute B cell concentrations. The data obtained suggest that T and B cell populations in the peripheral blood are reduced in certain patients with Crohn's disease and that this occurs secondarily to activity of disease, chronicity of disease, and the effects of therapy.