Variable responses of species and strains to white mineral oils and paraffin waxes.

Recent dietary studies on mineral hydrocarbon (MHC) white oils and waxes have shown inflammatory effects in Fischer 344 (F-344) rats, but not in other rat strains or dogs. Histopathologic effects seen in F-344 rats include mesenteric lymph node histiocytosis, liver granulomas, and inflammation of the mitral valve (only seen with paraffin waxes). Human ingestion of MHC can result in noninflammatory lipogranulomas (oil droplets) in tissues which are regarded as clinically unimportant. It is speculated that inherent interspecies differences in pharmacokinetics and/or immune function may contribute to the differential response to MHC seen in F-344 rats. The F-344 rat retains greater amounts of MHC in target tissues compared to other rat strains and dogs and appears to be more sensitive immunologically to MHC than other species, including humans. This strain may be predisposed to these effects as indicated by a high background incidence of inflammatory granulomatous lesions in control female F-344 rats. Because of its apparently unique sensitivity, relevance of effects seen in F-344 rat to human health is questionable and requires further investigation.

Association of Propionibacterium acnes endophthalmitis with HLA-DQw5.

BACKGROUND: An HLA-DQ1 association has been suspected in patients who develop Propionibacterium acnes endophthalmitis following cataract surgery. New techniques exist which may help to define this association. MATERIALS AND METHODS: Patients with culture-proven P. acnes endophthalmitis following cataract surgery were HLA-typed with new sera able to detect fine specificities in the HLA-DQ1 region and compared to a large number of racially-matched controls. Sequence-specific oligonucleotide typing with probes and primers designed to amplify and define the HLA-DQ1 region was then performed. P. acnes patients were compared to HLA-DQ1-matched controls who had undergone cataract surgery but had no evidence of chronic post-operative inflammation. RESULTS: Thirteen of 15 P. acnes patients (87%) were serologically defined as carrying a split of DQw1 (DQw5 or DQ26). HLA DQw5 was increased to a statistically significant degree (p < 0.014) with an odds ratio of 3.72 (95% confidence interval 1.34 to 10.31). Sequence-specific oligonucleotide typing confirmed the DQw5 predominance: Seventy-three percent of P. acnes patients had DQB1 (*)0501 or DQB1 (*)0503 vs. 33% of DQw1-matched cataract patients without inflammation (not significant). CONCLUSION: HLA-DQ2w5 is associated with the development of P. acnes endophthalmitis following cataract surgery. The molecular mechanism of this association is unknown.