Urinary excretion of CD23 antigen in normal individuals and patients with chronic lymphocytic leukaemia (CLL)

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Abstract
A soluble form ol'CD23 (sCD23) was found in the urine from 12 normal individuals but was not present in 20 normal sera, suggesting that sCD23 produced by cells in tissues is eliminated in the urine. The sCD23 from urine differed in physicochemical properties from the sCD23 found in supernales from B-lymphoblastoid cell lines (B-LCL) and in the sera ol'patients with B type chronic lymphocytic leukaemia (B-CLL). On SDS-PAGE analysis under reducing conditions urinary sCD23 showed two bands corresponding to molecular weights of 45 60 kD and 2S 35 kD indicating that sCD23may be excreted in combination with another molecule. When subjected to gel iiltration in its native state. sCD23 from urine showed a major peak at approximately 150 kD and a minor peak (probably a breakdown product) at 21 kD. Urinary sCD23 was more strongly held by DEAE-cellulose and required 0–5 m buffer pH 8·0 for elution. suggesting that it is more anionic than sCD23 from culture supcrnates. Five MoAbs recognizing different epitopes on sCD23 from B-LCL supernales were tested on urinary sCD23. Four of the MoAbs were reactive but one (EBVCS-1) was not. Urinary sCD23 did not bind to IgE. The level of sCD23 found in normal urine (approximately 0·02–0·05 μg/ml) was exceeded in 17 of 24 cases of B-CLL. In one case with a high cell count and a serum concentration of 10 μg/ml. the urine contained 80 μg/ml sCD23. In another case a high serum sCD23 was not matched by a high urinary level. In thiscase the gel filtration pattern was closer to that found with urine sCD23 rather than the B-LCL pattern found with sera of other B-CLL patients.
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