Selective antipolysaccharide antibody deficiency associated with peripheral blood CD5+ B-cell predominance

Primary humoral deficiencies vary from complete absence of B cells and/or serum immunoglobulin to lacunar deficits involving specific antibody responses to polysaccharides.

We compared the B-cell CD5 expression in patients with selective antipolysaccharide antibody deficiencies (SPADs), common variable immunodeficiency (CVID), and IgG subclass deficiency and in normal control subjects.

Five patient populations were evaluated: (1) patients with severe SPAD (no protective serologic postvaccine response to any of 12 polysaccharide antigens tested); (2) patients with intermediate SPAD (diminished response to polysaccharide antigens and adequate response to 1 to 3 of 12 serotypes tested); (3) patients with IgG subclass deficiency; (4) patients with CVID; and (5) age-matched control subjects. Blood was collected from all patients and evaluated by using flow cytometry. Results were compared by using the Student t test.

Patients with severe SPAD deficiencies had a marked predominance of CD5+ B cells in the peripheral blood (93% to 97% of total B cells, n = 2). The intermediate SPAD group had a mean CD5+ B-cell percentage that was significantly higher than that of the age-matched control group (87. 4%, n = 7, vs 52.5%, n = 20; P =.007). Patients with CVID and IgG subclass deficiency had mean CD5+ B-cell percentages that were similar to those of the age-matched control subjects.

Our studies demonstrate that patients with SPAD had a markedly increased percentage of CD5+ B cells in the peripheral blood as compared with age-matched control subjects and patients with other humoral deficiencies. This observation suggests that an association may be present between CD5+ B-cell predominance and SPAD.