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POPULATION SCREENING FOR B-CELL MONOCLONAL LYMPHOCYTOSIS USING PCR AND FLOW CYTOMETRY TO DETERMINE IMMUNOPHENOTYPES   A JACK, S RICHARDS, P EVANS AND C WILKS   STUDY 1   Design  
    This study carried out immunophenotyping by a standard two colour method on all patients who were found to have a total lymphocyte count of greater than 4.5 x 10 9 /l on routine blood count without clinical suspicion of haematological malignancy. Patients were recruited from all hospitals in Yorkshire (population: 2.3M) over a 15 month period.
  Results  
    A total of 870 samples were studied of which 78 (9%) had a clonal B-cell population by surface light chain restriction. 41 of these 78 cases had a CLL type phenotype defined as weak sIg, CD5, CD23 expression. The phenotypes of the remaining cases were heterogenous.
  Comment  
    Although it was not possible to calculate ascertainment in this study, the participation rate among district hospital laboratories in the region appears to have been good.
  STUDY 2   Design  
    1000 peripheral blood samples were studied from patients aged 40-70 who had normal haematological indices on a routine blood sample and no history or suspicion of haematological malignancy. 971 were suitable for analysis.  All samples were from patients admitted for elective surgery in gynaecology, ophthalmology or general surgery or to the cardiology department in patients with suspected myocardial infarction or routine screening carried out by general practitioners. For ethical reasons the samples were selected by staff not involved in the study and had patient identification removed.
 
    All samples were screened using a three colour (FITC, PE, CY5) flow cytometric technique with light chain expression, CD5, CD23, CD20 and CD11a related to CD19 expression. Cases with increased numbers of CD5 B-cells or an abnormal Kappa:Lambda ratio were studied using IgH PCR (protocol available).
  Results  
    The total lymphocyte count for this population approximates to a normal distribution with a mean of 1.98, standard deviation 0.7 and a maximum value of 4.7 x 10 9 /1. In contrast, the total B-cell counts and CD5 positive B-cell counts had a skewed distribution (See Figures 1 and 2). In 2.90% of cases the CD5 positive B-cell count was greater than mean value + 2SD. In 3.70% of cases the number of B-cells was greater than mean + 2SD. In 1.1% of cases the Kappa:Lambda ratio was outside the range 0.5-3.0.
 
    The PCR data which could be retrieved was incomplete but using conservative assumptions, the incidence of monoclonality is approximately 1.7%.  Problems with data handling also made it impossible to correlate clonality with detailed phenotypic features.
  Comment  
    Problems in data handling makes the results of study 2 less valuable than might have been hoped. However, taking studies 1 and 2 together, the incidence of a clonal B-cell population in the peripheral blood of asymptomatic patients over 40 years in Yorkshire is likely to be in the range 1.5-2% mostly with normal lymphocyte counts.
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