Effects of basic proteins on spontaneous rosette formation between human lymphocytes and xenogeneic erythrocytes

Two basic proteins (methylated human serum albumin, MHSA, and protamine sulphate, PS) were investigated for their modulatory capacities on a panel of human lymphocyte surface markers. MHSA and PS enhanced the spontaneous rosettes with mouse, sheep and horse erythrocytes, but did not affect the number of rosettes with zymosan particles coated with human complement, or with sheep erythrocytes sensitized with rabbit anti-sheep IgG antibody. Whereas the standard sheep (E) rosette test was not influenced by the negatively charged glycoprotein ceruloplasmin, this compound could, however, abolish the MHSA- and PS-induced enhancements of the number of sheep rosettes. By double marker studies it was furthermore demonstrated that a subset of B cells was induced by MHSA to form E rosettes, and that the same agent increased the number of B cells forming mouse rosettes, so that nearly all B cells were made positive for this marker.