Anti-IgG Antibody [MT145] (A269901)

There is growing evidence to support the role of Fc-mediated effector functions, such as Antibody-Dependent Cellular cytotoxicity (ADCC) and Antibody-Dependent Phagocytosis (ADP) in the protection and control of HIV. The RV144 trial and other recent HIV vaccine studies have highlighted the importance of ADCC responses in protection against HIV. The role of neutrophils, the most abundant leukocyte in the blood, has not been thoroughly evaluated for Fc-mediated effector functions to HIV. We optimized HIV-specific neutrophil ADCC and Antibody-Dependent Neutrophil Phagocytosis (ADNP) assays using freshly isolated primary human neutrophils from blood. We also developed methods to study ADP using the neutrophil-like HL-60 cell line. We found that neutrophils mediate both HIV-specific ADP and ADCC responses. In vitro, neutrophil-mediated ADCC responses peaked at 4 h, much faster than primary NK cell or monocyte-mediated responses. We detected a wide range of responses in the ADNP, HL-60 mediated ADP and ADCC across a cohort of 41 viremic antiretroviral therapy naïve HIV positive subjects. HL-60 and Neutrophil-mediated ADP and ADCC responses correlated well with each other, suggesting that they measure overlapping functions. The ADNP and HL-60 ADP inversely correlated with HIV viral load, suggesting that these antibody-mediated neutrophil-based assays should prove useful in dissecting HIV-specific immunity.

Human African trypanosomiasis (HAT) patients manifest immunological profiles, whose variations over time can be used to indicate disease progression. However, monitoring of these biomarkers in human patients is beset by several limitations which can be offset by using chronic animal models. A recent improved monkey model of HAT using a Trypanosoma brucei brucei isolate has been developed but the immunological profile has not been elucidated. The objectives of the current study was to determine the IgM, IgG and IL-6 profiles in blood and cerebrospinal fluid (CSF) in vervet monkeys infected with T. b. brucei. Three vervet monkeys were infected intravenously with 10⁵T. b. brucei, monitored for disease development and subsequently treated 28days post infection (dpi) sub-curatively using diminazene aceturate (DA) to induce late stage disease and curatively treated with melarsoprol (Mel B) at 119 dpi, respectively. Matched serum and cerebrospinal fluid (CSF) samples were obtained at regular intervals and immunospecific IgM, immunoglobulin G (IgG) were quantified by ELISA while IL-6 was assayed using a cytometric bead array (CBA) kit. Results showed that following infection, CSF IgM, IgG, IL-6 and serum IL-6 were significantly (p<0.05) elevated with peak levels coinciding with relapse parasitaemia. The IgG levels increased to reach OD peak levels of 0.442±0.5 at 126 dpi. After curative treatment with MelB, the serum IgM and Ig G levels fell rapidly to attain pre-infection levels within 35 and 49days, respectively. This shows that the profile of these immunoglobulins can be used as an indicator of curative treatment. CSF IL-6 concentrations of infected vervet monkeys showed no significant change (P>0.05) between infection and 35 dpi but levels increased significantly (P<0.05) with the highest level of 55.53pg/ml recorded at112 dpi. IL-6 elevation from 35 dpi may be indicative of parasite neuroinvasion hence can be used as possible candidate marker for late stage disease in the monkey model. Further, the marker can also be used in conjunction with IgG and IgM as markers for development of test of cure for HAT.

Japanese macaque encephalomyelitis (JME) is an inflammatory demyelinating disease that occurs spontaneously in a colony of Japanese macaques (JM) at the Oregon National Primate Research Center. Animals with JME display clinical signs resembling multiple sclerosis (MS), and magnetic resonance imaging reveals multiple T2-weighted hyperintensities and gadolinium-enhancing lesions in the central nervous system (CNS). Here we undertook studies to determine if JME possesses features of an immune-mediated disease in the CNS. Comparable to MS, the CNS of animals with JME contain active lesions positive for IL-17, CD4+ T cells with Th1 and Th17 phenotypes, CD8+ T cells, and positive CSF findings.

Background: Genetic polymorphisms in the complex gene cluster encoding human Fc-gamma receptors (Fc?Rs) may influence malaria susceptibility and pathogenesis. Studying genetic susceptibility to malaria is ideal among sympatric populations because the distribution of polymorphic genes among such populations can help in the identification malaria candidate genes. This study determined the distribution of three FcyRs single nucleotide polymorphisms (SNPs) (Fc?RIIB-rs1050519, Fc?RIIC-rs3933769 and Fc?RIIIA-rs396991) among sympatric Fulani and Dogon children with uncomplicated malaria. The association of these SNPs with clinical, malariometric and immunological indices was also tested.

Methods: This study involved 242 Fulani and Dogon volunteers from Mali age under 15 years. All SNPs were genotyped with predesigned TaqMan(®) SNP Genotyping Assays. Genotypic and allelic distribution of SNPs was compared across ethnic groups using the Fisher exact test. Variations in clinical, malariometric and immunologic indices between groups were tested with Kruskal-Wallis H, Mann-Whitney U test and Fisher exact test where appropriate.

Results: The study confirmed known malariometric and immunologic differences between sympatric Fulani and non-Fulani tribes. Parasite density was lower in the Fulani than the Dogon (p < 0.0001). The mutant allele of Fc?RIIC (rs3933769) was found more frequently in the Fulani than the Dogon (p < 0.0001) while that of Fc?RIIIA (rs396991) occurred less frequently in the Fulani than Dogon (p = 0.0043). The difference in the mutant allele frequency of Fc?RIIB (rs1050519) between the two ethnic groups was however not statistically significant (p = 0.064). The mutant allele of rs396991 was associated with high malaria-specific IgG1 and IgG3 in the entire study population and Dogon tribe, p = 0.023 and 0.015, respectively. Parasite burden was lower in carriers of the Fc?RIIC (rs3933769) mutant allele than non-carriers in the entire study population (p < 0.0001). Carriers of this allele harboured less than half the parasites found in non-carriers.

Conclusion: Differences in the allelic frequencies of rs3933769 and rs396991 among Fulani and Dogon indirectly suggest that these SNPs may influence malaria susceptibility and pathogenesis in the study population. The high frequency of the Fc?RIIC (rs3933769) mutant allele in the Fulani and its subsequent association with low parasite burden in the entire study population is noteworthy.