Cell surface and enzyme markers of cord blood lymphocytes.

Human cord blood (CB) lymphocytes were studied with several markers for T- and B-cells and the results compared with those of adult peripheral blood (PB) samples. The proportion of E-rosettes was significantly lower in CB (mean 24.7+/-13.5 SD) than in PB (67.5+/-7.3 SD). Treatment with neuramidase produced a marked increase in the proportion of E-rosettes in CB (mean 47 +/-13.9 SD), still below the PB values. The proportion of CB lymphocytes showing block positivity with alpha-naphthyl-acetate-esterase correlated closely with the percentage of E-rosettes in neuraminidase treated cells. The percentage of H-rosettes (human RBC) was significantly higher in CB (7.2+/-6.0) than in PB (3.2+/-1.6 SD). Re-rosetting experiments showed that in CB about 30% of the E-positive cells formed H-rosettes, in contrast to 5% in PB. These findings indicate that in CB the real number of T-lymphocytes is higher than shown by conventional E-rosette formation. The proportion of B-lymphocytes, tested by surface immunoglobulins and by rosette formation with mouse RBC (M-rosettes), was similar in CB and in adult PB. A slight increase in cells with IgM on the surface was found in CB. The overall proportion of lymphocytes with negative B and T markers in CB is three times greater than in adult PB. Levels of the enzyme terminal deoxynucleotidyl transferase were marginally increased in CG; in two out of 41 samples the levels were above those found in normal bone marrow. CB may be a suitable model for the study of lymphocyte subsets with negative B and T markers in man.