DISTRIBUTION OF LYMPHOCYTE SUBSETS IN BONE-MARROW AND PERIPHERAL-BLOOD IS ASSOCIATED WITH HAPTOGLOBIN TYPE - BINDING OF HAPTOGLOBIN TO THE B-CELL LECTIN CD22

Haptoglobin is an acute phase protein showing a genetic polymorphism w ith 3 major types: Hp 1-1, Hp 2-1, and Hp 2-2. In this study, flow cyt ometric analysis demonstrated that all three haptoglobin types bind to CD22 on human B-lymphocytes with equal affinity. Comparison of refere nce values for lymphocyte subsets in peripheral blood and bone marrow showed significant differences between haptoglobin types. Haptoglobin 2-2 is associated with higher peripheral B-lymphocyte counts (P <0.001 ) and CD4(+) T-lymphocyte counts (P <0.05). In bone marrow, CD4(+) T-c ell percentages were highest (P <0.001) but B-cell percentages were lo west (P <0.001) in haptoglobin 2-2 type. A negative correlation betwee n serum haptoglobin 1-1 concentration and peripheral B-cell counts was observed (r=-0.663). Our results suggest that haptoglobin is involved in lymphocyte distribution. The present findings are a potential caus e of over- or underestimation of lymphocyte subset counts in the clini cal staging of immunodeficiency diseases.