A study of HLA class I and class II 4-digit allele level in Stevens-Johnson syndrome and toxic epidermal necrolysis.

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are represented by rare but life-threatening cutaneous adverse reactions to different drugs. Previous studies have found that in a Han Chinese population from Taiwan and other Asian Countries, a strong genetic association between HLA-class I alleles (B*15:02, B*58:01) and SJS and TEN was induced by carbamazepine and allopurinol, respectively. To identify genetic markers that covered the MHC region, we carried out a case-control association enrolling 20 Caucasian patients with SJS/TEN. Our patient series included 10 cases related to paracetamol, 7 to allopurinol and 3 to different drugs (plaquenil, itraconazol, nabumetone). Healthy controls were represented by 115 Caucasian bone marrow or stem cell donors. The HLA-A*, B*, C*, DRB1*, DQB1*, DQA1* and DPB1* genotyping were determined. The frequencies of HLA-A*33:03 as well as C*03:02 and C*08:01 were significantly higher in SJS/TEN patient subgroup showing allopurinol drug-induced severe cutaneous adverse reactions (SCAR) as compared to controls (28.6% vs 0%, P=0.00002, Pc=0.0011; 28.6% vs 0%, P=0.00002, Pc=0.001; 28.6% vs 0%, P=0.00002, Pc=0.001, respectively). In the same subgroup the frequencies of B*58:01, DRB1*15:02 and DRB1*13:02 alleles, although considerably higher than in control group (42.8% vs 5.2%, P=0.003; 28.6% vs 1.7%, P=0.005; 28.6% vs 3.5%, P=0.037, respectively), appeared no more statistically different after P correction (Pc=0.248; Pc=0.29; Pc=1.00, respectively). In addition, in 10 of the 20 SJS/TEN patient subgroup with paracetamol-induced SCAR no statistically significant association with HLA alleles could be found. However, in the same SJS/TEN patient subgroup showing allopurinol drug-induced SCAR, haplotype analysis indicated that B*58:01, DRB1*13:02 and DRB1*15:02 alleles, that in a single allele analysis lost statistical significance after P correction, may still confer susceptibility, because the B*58:01-DRB1*13:02 and DRB1*15:02-DQB1*05:02 are positively associated with the disease (14.2% vs 0.43%, P= 0.00001, Pc=0.00028; 14.2% vs 0.43%, P=0.00001, Pc=0.00028, respectively). Our results show that in contrast to SCAR-related to paracetamol, where HLA alleles do not appear to be involved, HLA molecules behave as a strong risk factor for SCAR-related to allopurinol even when a limited number of patients are considered.

Plateletpheresis during plasma collection.

New systems for collection of platelet concentrate (PC) and platelet poor plasma (PPP) are presently available. The aim of our work was to test the possibility of preparing PC routinely from normal plasma donors in a minimum amount of time and, at the same time, providing a second product that can be used as source-plasma or fresh-frozen plasma. Over a 3 year period (from 1990 to 1992) we performed 3503 procedures using 2 Haemonetics PCS machines (1236 procedures) and 3 Autopheresis-C (2267 procedures). With the PC produced we were able to satisfy all the requests coming from the hospitals of our region. The platelet yield was 1.95 x 10(11) with PCS and 3.2 x 10(11) with Auto-C in a PC volume of 150 and 200 ml respectively; collection times were quite similar (56 and 63 min). The results show that plasma-plateletpheresis is an efficient and competitive system. Regarding platelet yield, the best results were obtained with the Auto-C.