- April 1998 (77%). Coded archival sera were tested for HP positivity using a commercial ELISA kit (Wampole Labs, Cranbury, NJ) according to the manufacturer's instructions. Each sample was run in duplicate without knowledge of clinicopathological information. Serology results are reported as positive, negative, or equivocal based on controls provided in each kit. Equivocals, representing 2% of the total, were counted as positive. Results: Total NHL lid CLL CML AL HCL Other Pts (No.) 415 183 59 69 7 19 10 68 HP+ 38% 43% 19% 39% 29% 37% 30% 43% Age, median 55 61 28 59 34 51 52 60 The overall HP seroprevalence (38%) is typical of this predominantly U.S. population. HP seroprevalence was similar among the diagnostic groups, except for a lower HP seropo~itivity in HD (p<0.05; chi-square). The apparent decrease in HP seropositivity in pts with HD was due to their younger age. When data were controlled for age at diagnosis, year of birth, or date of serum collection, no significant differences were found in HP prevalence among diagnostic groups. Within NHL, HP seropositivity was higher in pts with G1 than non-G1 lymphomas (54% vs 40%; p=0.17). There was no difference in HP seropositivity between gastric and nongastric GI NHL (54% vs 55%). Of 8 gastric MALT lymphomas, 6 (75%) were HP+. Conclusions: Pts with G1 NHL had a higher HP seropositivity rate than those with non-G1 NHL. However, gastric NHL HP seropositivity rates were not statistically different from lymphomas in other GI sites. In this sizable population, pts with NHL did not show a greater HP seropositivity rate than those with other hematological disorders.