Specificity and Diversity of Antibodies toMycobacterium tuberculosisArabinomannan

Abstract

Arabinomannan (AM) is a polysaccharide antigen of the mycobacterial capsule. However, it is uncertain whether AM constitutes an immunologically distinct fraction of Mycobacterium tuberculosis. In this study, we analyzed the repertoire and specificity of antibodies to AM by using AM-binding murine monoclonal antibodies (MAbs) and human serum samples. Murine MAbs were found to be diverse in their specificity to AM and cross-reactivity with other arabinose-containing mycobacterial polysaccharides, with MAb 9d8 binding exclusively to AM. Human antibodies to AM were detected in serum samples from patients with pulmonary tuberculosis (TB), as well as in those from healthy, purified protein derivative-negative controls, with significantly higher titers among patients. The binding of human antibodies to AM was inhibited by MAb 9d8 in three patients with TB but not in controls. MAb 5c11, which recognizes other mycobacterial arabinosecontaining carbohydrates in addition to AM, inhibited the binding of serum samples from 75% of patients and 76% of controls. Analysis of human antibodies with murine MAbs to human V H determinants demonstrated diversity among antibodies to AM with qualitative and quantitative differences compared with antibodies to lipoarabinomannan. In summary, our study suggests that antibodies to AM are diverse and heterogeneous with respect to antigen recognition and V H determinant expression, with human serum samples containing different subsets of antibodies to AM with the specificities of AM-binding murine MAbs. One MAb and a subset of human antibodies bind AM specifically, suggesting that this polysaccharide is antigenically distinct and is expressed in human infection.

Antigenic Evidence of Prevalence and Diversity ofMycobacterium tuberculosisArabinomannan

“…MAb 9d8 was previously shown to react specifically with AM (19) without cross-reacting with other arabinose-containing surface polysaccharides. On the other hand, other AM-binding MAbs also bind to the AM found in LAM, and some cross-react with AG (19). Previous studies have shown that the amount of AM generated by M. tuberculosis increases in a time-dependent manner (23).…”

“…This finding prompted us to examine whether AM is present on the surfaces of different M. tuberculosis strains. The presence of AM on the surfaces of M. tuberculosis isolates was examined by whole-cell ELISA with several AM-binding MAbs with different specificities (19). MAb 9d8 was previously shown to react specifically with AM (19) without cross-reacting with other arabinose-containing surface polysaccharides.…”

Monoclonal antibodies to Mycobacterium tuberculosis CDC 1551 reveal subcellular localization of MPT51

“…RNA was prepared from hybridoma cell lines 16a1 and 16a6 as previously described (23). RNA was used for the synthesis of cDNA from mRNA, using oligo(dT) primer and superscript II reverse transcriptase (GIBCO).…”

“…RNA was used for the synthesis of cDNA from mRNA, using oligo(dT) primer and superscript II reverse transcriptase (GIBCO). The cDNA encoding the immunoglobulin variable domains was then amplified by PCR as previously described (23), using the following universal 5′ (sense) variable-region and specific 3′ (antisense) constant region primers: 3′msCgamma, AGA CCG ATG GGG CTG TTG TTT TGG C; 3′msCkappa, TGG ATA CAG TTG GTG CAG CAT CAG C; 5′vh Uni, TGA GGT GCA GCT GGA GGA GTC; 5′Vk Uni GAC ATT CTG ATG ACC CAG TCT. PCR products (Qiagen) were ligated into pCR2.1 (Invitrogen) according to manufacturer instructions.…”

Capsular Arabinomannans from Mycobacterium avium with Morphotype-specific Structural Differences but Identical Biological Activity

“…These immunomodulatory properties have ultimately led to the use of such compounds in vaccination against mycobacterial infections and as immunotherapeutic agents in cancer therapy (11)(12)(13)(14)(15)(16)(17)(18)(19). AMs preparations show profound anti-tumor activity in murine experimental cancer models, and mechanistic studies reveal that the anti-tumor activity of AMs depends on distinct immune cell populations and TH1 cytokines (16,17).…”