IngentaConnect Influence of age and HLA type on interferon-gamma (IFN-) response...

Authors: Bucci, K.¹; Kastens, W.¹; Hollingdale, M. R.²; Shankar, A.³; Alpers, M. P.⁴; King, C. L.¹; Kazura, J. W.¹

Source: Clinical & Experimental Immunology, Volume 122, Number 1, October 2000 , pp. 94-100(7)

Abstract:

Antigenic polymorphism and HLA restriction may limit the immunogenicity of a subunit vaccine against liver-stage Plasmodium falciparum. We examined 59 clinical isolates and five laboratory clones of P. falciparum for polymorphism in the N- and C-terminal regions of LSA-1, evaluated binding of the corresponding peptides to selected HLA class I alleles, and measured IFN-γ responses in residents of a malaria-endemic area of Papua New Guinea where HLA-A*1101, -24, -B13, and -B40 are the most common class I alleles. LSA-1 polymorphism was limited to a single non-synonymous mutation encoding serine (S), proline (P), or threonine (T) at amino acid 85. Nine-mer 84-92 peptides with S, T, or P at the primary anchor position bound differentially to HLA-A11, -A2, and -B7. IFN-γ ELISPOT responses increased with age in malaria-exposed subjects: 14-16% and 30-36% of 2-5- and 6-54-year-olds, respectively, had ≥ 10 IFN-γ-secreting cells/10⁶ peripheral blood mononuclear cells when stimulated with at least one peptide variant (P < 0·05). IFN-γ responses to all three peptides were also greater for older than younger individuals. No children < 3 years old had lymphocytes that responded to all three 84-92 peptides, whereas 45% of adults (mean age 48 years) had aggregated IFN-γ responses. These data support the notion that age-related cumulative exposure to P. falciparum increases the frequency of IFN-γ responses to polymorphic epitopes of liver-stage antigens such as LSA-1.

Keywords: malaria; HLA; LSA-1; polymorphism; cytokine

Document Type: Research article

DOI: 10.1046/j.1365-2249.2000.01346.x

Affiliations: 1: Division of Geographic Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, USA, 2: Department of Biology, University of Leeds, Leeds, UK, 3: Departments of International Health and Molecular Microbiology and Immunology, Johns Hopkins School of Hygiene and Public Health, Baltimore, MD, USA 4: Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea, and

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Influence of age and HLA type on interferon-gamma (IFN-γ) responses to a naturally occurring polymorphic epitope of Plasmodium falciparum liver stage antigen-1 (LSA-1)