CD8A and Hermansky-Pudlak syndrome: Furthermore, during the acute phase of HFRS and in fatal HPS cases, cellular infiltrates consisting of disproportionately large numbers of activated CD8+ T cells have been reported and genetic correlations between disease severity and HLA haplotype have been observed in patients with milder forms of HFRS and HPS [70–73] leading many to propose mechanisms of disease focused on T cell mediated immunopathology [73–77].