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

Background: Primary humoral deficiencies vary from complete absence of B ce lls and/or serum immunoglobulin to lacunar deficits involving specific anti body responses to polysaccharides, Objectives: We compared the B-cell CD5 expression in patients with selectiv e antipolysaccharide antibody deficiencies (SPADs), common variable immunod eficiency (CVID), and IgG subclass deficiency and in normal control subject s, Methods: Five patient populations were evaluated: (1) patients with seve re SPAD (no protective serologic postvaccine response to any of 12 polysacc haride antigens tested); (2) patients with intermediate SPAD (diminished re sponse to polysaccharide antigens and adequate! response to 1 to 3 of 12 se rotypes tested); (3) patients with IgG subclass deficiency; (4) patients wi th CVID; and (5) age-matched control subjects. Blood was collected from all patients and evaluated by using flow cytometry. Results were compared by u sing the Student t test. Results: Patients with severe SPAD deficiencies had a marked predominance o f 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 si gnificantly higher than that of the ape-matched control group (87.4%, n = 7 , vs 52.5%, n = 20; P =.007), Patients with CVID and IgG subclass deficienc y had mean CD5+ B-cell percentages that were similar to those of the age-ma tched control subjects. Conclusions: Our studies demonstrate that patients with SPAD had a markedly increased percentage of CD5+ B cells in the peripheral blood as compared w ith age-matched control subjects and patients with other humoral deficienci es. This observation suggests that an association may be present between CD 5+ B-cell predominance and SPAD.