Screening plasma donors for high-titre antibody to cytomegalovirus using a latex agglutination test.

Cytomegalovirus (CMV) can cause severe morbidity in immunosuppressed patients. Regional transfusion centres in the UK are required to supply high-titre anti-CMV plasma to the Blood Products Laboratory (BPL), now called 'Bio-Products Laboratory', for the production of specific intravenous immunoglobulin at the Protein Fractionation Centre in Scotland. For this purpose, 703 plasmapheresis donors were screened by a modified latex agglutination test to assess their suitability as donors with high-titre anti-CMV. CMV antibodies were found in 48% of the donors. Seropositivity increased with age ranging from 33% in the 20- to 29-year age group to 57% in the 40-49 age group, although the 50-59 age group showed a slight decline to 53%. In all age ranges except the 40-49 group, seropositivity was highest in the female population. With the latex test, 14% of the total donors screened had a titre greater than or equal to 1 in 64, 7% greater than or equal to 1 in 128 and 4.2% greater than or equal to 1 in 256. Samples from 18 donors with titres greater than or equal to 1 in 128 were sent to BPL and all samples were found to have a sufficiently high titre for the production of CMV immune plasma. For BPL the 'cut-off' level for CMV immune plasma is a titre greater than or equal to 1 in 64 by complement fixation. Since the establishment of a panel of donors with high-titre anti-CMV plasma, more than 10 kg of plasma are dispatched monthly from our centre to BPL.