The Grifols DG Gel(®) 8-column system is reliable and safe for routine tests performed in the immunohaematology laboratory.

A 79-year-old male had anaemia and apparent thrombocytosis on routine blood analysis (haemoglobin 10AE6 g/dl, white blood cell (WBC) count 2AE7 · 10 9 /l, platelet count 916 · 10 9 /l); however, when analysed on an optical analyser, the true platelet count was found to be low (haemoglobin 10AE9 g/dl, WBC count 2AE8 · 10 9 /l, platelet count 79 · 10 9 /l). The apparent thrombocythaemia was due to multiple needle-like crystals that formed as the sample cooled (the upper left panel shows freshly collected blood with early crystal formation, the upper right panel shows prominent needle-like crystals appearing as the blood was allowed to cool). Immunological investigation confirmed a monoclonal immunoglobulin (immunoglobulin Gk 4AE1 g/l) that precipitated on cooling (type 1 cryoglobulin). To confirm the nature of the unusual crystals, they were purified and separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (bottom left panel), and the protein components identified using matrixassisted laser desorption/ionisation-time of flight mass spectrometry and peptide-mass finger printing. The peptidemass fingerprint of one of the protein components (indicated as band B on the gel) is shown in the lower right panel: the three indicated peptides identified this band as being the heavy chain of immunoglobulin. The other major bands (A and C) were identified respectively as albumin (a typical component of cryoglobulin) and immunoglobulin light chain. The cause of the unusual crystal shape seen in this patient may relate to unusual 'self-assembly' characteristics of the monoclonal immunoglobulin.