Measurement of ferritin-bearing lymphocytes in man. Preliminary studies on the use of monoclonal antibodies specific for the L and H subunits of ferritin.

We used the monoclonal antibodies LFO3 (specific for the L subunit of ferritin) and 2A4 (specific for the H subunit) in an indirect immunofluorescence test for enumerating ferritin-bearing lymphocytes (FBL). In 13 normal subjects, the geometric mean value of FBL was 4% (range 0-13%) with the monoclonal antibody LFO3, and 3% (range 0-8%) with the monoclonal antibody 2A4. Values in 5 subjects with transfusional iron overload and increased plasma L-type ferritin concentration were 5% (4-7%) and 3% (2-4%), respectively, which is similar to those in normal subjects. Thirteen patients with malignant disease had normal to increased values for plasma ferritin; the circulating protein was largely of L-type with undetectable or very low concentrations of H-type ferritin. In the same patients, the percentage of FBL was greater with the monoclonal antibody 2A4 (geometric mean value 8%; range 3-12%) than with the monoclonal antibody LFO3 (geometric mean value 3%; range, 1-7%). It is concluded that acidic and basic isoferritins can be differently expressed on the surface of peripheral blood lymphocytes, and that the monoclonal 2A4 could be particularly useful in the measurement of FBL in patients with malignancy.