CD200 is a useful diagnostic marker for identifying atypical chronic lymphocytic leukemia by flow cytometry.

INTRODUCTION: Immunophenotyping by flow cytometry is routinely employed in distinguishing between chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). Inclusion of CD200 has been reported to contribute to more reliable differentiation between CLL and MCL. We investigated the value of CD200 in assessment of atypical CLL cases. METHODS: CD200 expression on mature B cell neoplasms was studied by eight-color flow cytometry in combination with a conventional panel of flow cytometry markers. The study included 70 control samples, 63 samples with CLL or atypical CLL phenotype, 6 MCL samples, and 40 samples of other mature B cell neoplasms. RESULTS: All CLL samples were positive for CD200, whereas MCL samples were dim or negative for CD200. Of the CLL samples, 7 were atypical by conventional flow cytometry, with Matutes scores ≤3. These cases were tested for evidence of a t(11;14) translocation, characteristic of MCL, and all were negative, consistent with their classification as atypical CLL. All these atypical CLL samples were strongly positive for CD200. CONCLUSION: CD200 proved to be a useful marker for differentiation between CLL and MCL by flow cytometry. In particular, CD200 was useful in distinguishing CLL samples with atypical immunophenotypes from MCL.

Haemoglobin Manukau beta 67[E11] Val-->Gly: transfusion-dependent haemolytic anaemia ameliorated by coexisting alpha thalassaemia.

Haemoglobin Manukau (beta 67 Val-->Gly) is a novel haemoglobin variant presenting in two brothers as nonspherocytic haemolytic anaemia which became transfusion dependent by 6 months of age. The severity of clinical expression seems to be modulated by coexisting alpha thalassaemia: the severely affected children have a normal complement of alpha globin genes with an unusual genotype (-alpha 3.7/alpha alpha alpha 3-7), while their father, who carries the abnormal gene with minimal symptoms, has homozygous alpha+ thalassaemia (-alpha 3.7/-alpha 3.7). Another unusual feature of this case is the association of the beta 67 Val-->Gly mutation with modification of beta 141 Leu to a residue (believed to be hydroxyleucine) that is not detected by standard amino acid analysis. This finding offers an explanation for the previous report of an association of another mutation at this site (Hb Sydney beta 67 Val-->Ala) with Hb Coventry (deletion of beta 141 Leu).