Maturation and Diversity of the VRC01-Antibody Lineage over 15 Years of Chronic HIV-1 Infection.

HIV-1-neutralizing antibodies develop in most HIV-1-infected individuals, although highly effective antibodies are generally observed only after years of chronic infection. Here, we characterize the rate of maturation and extent of diversity for the lineage that produced the broadly neutralizing antibody VRC01 through longitudinal sampling of peripheral B cell transcripts over 15 years and co-crystal structures of lineage members. Next-generation sequencing identified VRC01-lineage transcripts, which encompassed diverse antibodies organized into distinct phylogenetic clades. Prevalent clades maintained characteristic features of antigen recognition, though each evolved binding loops and disulfides that formed distinct recognition surfaces. Over the course of the study period, VRC01-lineage clades showed continuous evolution, with rates of ∼2 substitutions per 100 nucleotides per year, comparable to that of HIV-1 evolution. This high rate of antibody evolution provides a mechanism by which antibody lineages can achieve extraordinary diversity and, over years of chronic infection, develop effective HIV-1 neutralization.

Structural Repertoire of HIV-1-Neutralizing Antibodies Targeting the CD4 Supersite in 14 Donors.

The site on the HIV-1 gp120 glycoprotein that binds the CD4 receptor is recognized by broadly reactive antibodies, several of which neutralize over 90% of HIV-1 strains. To understand how antibodies achieve such neutralization, we isolated CD4-binding-site (CD4bs) antibodies and analyzed 16 co-crystal structures -8 determined here- of CD4bs antibodies from 14 donors. The 16 antibodies segregated by recognition mode and developmental ontogeny into two types: CDR H3-dominated and VH-gene-restricted. Both could achieve greater than 80% neutralization breadth, and both could develop in the same donor. Although paratope chemistries differed, all 16 gp120-CD4bs antibody complexes showed geometric similarity, with antibody-neutralization breadth correlating with antibody-angle of approach relative to the most effective antibody of each type. The repertoire for effective recognition of the CD4 supersite thus comprises antibodies with distinct paratopes arrayed about two optimal geometric orientations, one achieved by CDR H3 ontogenies and the other achieved by VH-gene-restricted ontogenies.

Multidonor analysis reveals structural elements, genetic determinants, and maturation pathway for HIV-1 neutralization by VRC01-class antibodies.

Antibodies of the VRC01 class neutralize HIV-1, arise in diverse HIV-1-infected donors, and are potential templates for an effective HIV-1 vaccine. However, the stochastic processes that generate repertoires in each individual of >10(12) antibodies make elicitation of specific antibodies uncertain. Here we determine the ontogeny of the VRC01 class by crystallography and next-generation sequencing. Despite antibody-sequence differences exceeding 50%, antibody-gp120 cocrystal structures reveal VRC01-class recognition to be remarkably similar. B cell transcripts indicate that VRC01-class antibodies require few specific genetic elements, suggesting that naive-B cells with VRC01-class features are generated regularly by recombination. Virtually all of these fail to mature, however, with only a few-likely one-ancestor B cell expanding to form a VRC01-class lineage in each donor. Developmental similarities in multiple donors thus reveal the generation of VRC01-class antibodies to be reproducible in principle, thereby providing a framework for attempts to elicit similar antibodies in the general population.

Developmental pathway for potent V1V2-directed HIV-neutralizing antibodies.

Antibodies capable of neutralizing HIV-1 often target variable regions 1 and 2 (V1V2) of the HIV-1 envelope, but the mechanism of their elicitation has been unclear. Here we define the developmental pathway by which such antibodies are generated and acquire the requisite molecular characteristics for neutralization. Twelve somatically related neutralizing antibodies (CAP256-VRC26.01-12) were isolated from donor CAP256 (from the Centre for the AIDS Programme of Research in South Africa (CAPRISA)); each antibody contained the protruding tyrosine-sulphated, anionic antigen-binding loop (complementarity-determining region (CDR) H3) characteristic of this category of antibodies. Their unmutated ancestor emerged between weeks 30-38 post-infection with a 35-residue CDR H3, and neutralized the virus that superinfected this individual 15 weeks after initial infection. Improved neutralization breadth and potency occurred by week 59 with modest affinity maturation, and was preceded by extensive diversification of the virus population. HIV-1 V1V2-directed neutralizing antibodies can thus develop relatively rapidly through initial selection of B cells with a long CDR H3, and limited subsequent somatic hypermutation. These data provide important insights relevant to HIV-1 vaccine development.

Mechanisms That Shape Human Antibody Repertoire Development in Mice Transgenic for Human Ig H and L Chain Loci.

To determine the impact of the milieu on the development of the human B cell repertoire, we carried out a comprehensive analysis of productive and nonproductive Ig gene rearrangements from transgenic mice engineered to express single copies of the unrearranged human H chain and L chain Ig gene loci. By examining the nonproductive repertoire as an indication of the immediate product of the rearrangement machinery without an impact of selection, we discovered that the distribution of human rearrangements arising in the mouse was generally comparable to that seen in humans. However, differences between the distribution of nonproductive and productive rearrangements that reflect the impact of selection suggested species-specific selection played a role in shaping the respective repertoires. Although expression of some VH genes was similar in mouse and human (IGHV3-23, IGHV3-30, and IGHV4-59), other genes behaved differently (IGHV3-33, IGHV3-48, IGHV4-31, IGHV4-34, and IGHV1-18). Gene selection differences were also noted in L chains. Notably, nonproductive human VH rearrangements in the transgenic mice expressed shorter CDRH3 with less N addition. Even the CDRH3s in the productive rearrangements were shorter in length than those of the normal human productive repertoire. Amino acids in the CDRH3s in both species showed positive selection of tyrosines and glycines, and negative selection of leucines. The data indicate that the environment in which B cells develop can affect the expressed Ig repertoire by exerting influences on the distribution of expressed VH and VL genes and by influencing the amino acid composition of the Ag binding site.

Broad and potent neutralization of HIV-1 by a gp41-specific human antibody.

Characterization of human monoclonal antibodies is providing considerable insight into mechanisms of broad HIV-1 neutralization. Here we report an HIV-1 gp41 membrane-proximal external region (MPER)-specific antibody, named 10E8, which neutralizes ∼98% of tested viruses. An analysis of sera from 78 healthy HIV-1-infected donors demonstrated that 27% contained MPER-specific antibodies and 8% contained 10E8-like specificities. In contrast to other neutralizing MPER antibodies, 10E8 did not bind phospholipids, was not autoreactive, and bound cell-surface envelope. The structure of 10E8 in complex with the complete MPER revealed a site of vulnerability comprising a narrow stretch of highly conserved gp41-hydrophobic residues and a critical arginine or lysine just before the transmembrane region. Analysis of resistant HIV-1 variants confirmed the importance of these residues for neutralization. The highly conserved MPER is a target of potent, non-self-reactive neutralizing antibodies, suggesting that HIV-1 vaccines should aim to induce antibodies to this region of HIV-1 envelope glycoprotein.

Multiple Antibody Lineages in One Donor Target the Glycan-V3 Supersite of the HIV-1 Envelope Glycoprotein and Display a Preference for Quaternary Binding.

One of the goals of HIV-1 vaccine development is the elicitation of neutralizing antibodies against vulnerable regions on the envelope glycoprotein (Env) viral spike. Broadly neutralizing antibodies targeting the Env glycan-V3 region (also called the N332 glycan supersite) have been described previously, with several single lineages each derived from different individual donors. We used a high-throughput B-cell culture method to isolate neutralizing antibodies from an HIV-1-infected donor with high serum neutralization breadth. Clonal relatives from three distinct antibody lineages were isolated. Each of these antibody lineages displayed modest breadth and potency but shared several characteristics with the well-characterized glycan-V3 antibodies, including dependence on glycans N332 and N301, VH4 family gene utilization, a heavy chain complementarity-determining region 2 (CDRH2) insertion, and a longer-than-average CDRH3. In contrast to previously described glycan-V3 antibodies, these antibodies preferentially recognized the native Env trimer compared to monomeric gp120. These data indicate the diversity of antibody specificities that target the glycan-V3 site. The quaternary binding preference of these antibodies suggests that that their elicitation likely requires the presentation of a native-like trimeric Env immunogen. IMPORTANCE: Broadly neutralizing antibodies targeting the HIV-1 glycan-V3 region with single lineages from individual donors have been described previously. Here we describe three lineages from a single donor, each of which targets glycan-V3. Unlike previously described glycan-V3 antibodies, these mature antibodies bind preferentially to the native Env trimer and weakly to the gp120 monomer. These data extend our knowledge of the immune response recognition of the N332 supersite region and suggest that the mode of epitope recognition is more complex than previously anticipated.

HTJoinSolver: Human immunoglobulin VDJ partitioning using approximate dynamic programming constrained by conserved motifs.

BACKGROUND: Partitioning the human immunoglobulin variable region into variable (V), diversity (D), and joining (J) segments is a common sequence analysis step. We introduce a novel approximate dynamic programming method that uses conserved immunoglobulin gene motifs to improve performance of aligning V-segments of rearranged immunoglobulin (Ig) genes. Our new algorithm enhances the former JOINSOLVER algorithm by processing sequences with insertions and/or deletions (indels) and improves the efficiency for large datasets provided by high throughput sequencing. RESULTS: In our simulations, which include rearrangements with indels, the V-matching success rate improved from 61% for partial alignments of sequences with indels in the original algorithm to over 99% in the approximate algorithm. An improvement in the alignment of human VDJ rearrangements over the initial JOINSOLVER algorithm was also seen when compared to the Stanford.S22 human Ig dataset with an online VDJ partitioning software evaluation tool. CONCLUSIONS: HTJoinSolver can rapidly identify V- and J-segments with indels to high accuracy for mutated sequences when the mutation probability is around 30% and 20% respectively. The D-segment is much harder to fit even at 20% mutation probability. For all segments, the probability of correctly matching V, D, and J increases with our alignment score.

HIV-1 neutralizing antibodies display dual recognition of the primary and coreceptor binding sites and preferential binding to fully cleaved envelope glycoproteins.

The gp120 CD4 binding site (CD4bs) and coreceptor binding site (CoRbs) are two functionally conserved elements of the HIV-1 envelope glycoproteins (Env). We previously defined the presence of CD4bs-neutralizing antibodies in the serum of an HIV-1-infected individual and subsequently isolated the CD4bs-specific monoclonal antibodies (MAbs) VRC01 and VRC03 from the memory B cell population. Since this donor's serum also appeared to contain neutralizing antibodies to the CoRbs, we employed a differential fluorescence-activated cell sorter (FACS)-based sorting strategy using an Env trimer possessing a CoRbs knockout mutation (I420R) to isolate specific B cells. The MAb VRC06 was recovered from these cells, and its genetic sequence allowed us to identify a clonal relative termed VRC06b, which was isolated from a prior cell sort using a resurfaced core gp120 probe and its cognate CD4bs knockout mutant. VRC06 and VRC06b neutralized 22% and 44% of viruses tested, respectively. Epitope mapping studies revealed that the two MAbs were sensitive to mutations in both the gp120 CoRbs and the CD4bs and could cross-block binding of both CD4bs and CoRbs MAbs to gp120. Fine mapping indicated contacts within the gp120 bridging sheet and the base of the third major variable region (V3), which are elements of the CoRbs. Cell surface binding assays demonstrated preferential recognition of fully cleaved Env trimers over uncleaved trimers. Thus, VRC06 and VRC06b are Env trimer precursor cleavage-sensitive neutralizing MAbs that bind to a region of gp120 that overlaps both the primary and the secondary HIV-1 receptor binding sites.

Analysis of somatic hypermutation in X-linked hyper-IgM syndrome shows specific deficiencies in mutational targeting.

Subjects with X-linked hyper-IgM syndrome (X-HIgM) have a markedly reduced frequency of CD27(+) memory B cells, and their Ig genes have a low level of somatic hypermutation (SHM). To analyze the nature of SHM in X-HIgM, we sequenced 209 nonproductive and 926 productive Ig heavy chain genes. In nonproductive rearrangements that were not subjected to selection, as well as productive rearrangements, most of the mutations were within targeted RGYW, WRCY, WA, or TW motifs (R = purine, Y = pyrimidine, and W = A or T). However, there was significantly decreased targeting of the hypermutable G in RGYW motifs. Moreover, the ratio of transitions to transversions was markedly increased compared with normal. Microarray analysis documented that specific genes involved in SHM, including activation-induced cytidine deaminase (AICDA) and uracil-DNA glycosylase (UNG2), were up-regulated in normal germinal center (GC) B cells, but not induced by CD40 ligation. Similar results were obtained from light chain rearrangements. These results indicate that in the absence of CD40-CD154 interactions, there is a marked reduction in SHM and, specifically, mutations of AICDA-targeted G residues in RGYW motifs along with a decrease in transversions normally related to UNG2 activity.

An activation-induced cytidine deaminase-independent mechanism of secondary VH gene rearrangement in preimmune human B cells.

V(H) replacement is a form of IgH chain receptor editing that is believed to be mediated by recombinase cleavage at cryptic recombination signal sequences (cRSS) embedded in V(H) genes. Whereas there are several reports of V(H) replacement in primary and transformed human B cells and murine models, it remains unclear whether V(H) replacement contributes to the normal human B cell repertoire. We identified V(H)-->V(H)(D)J(H) compound rearrangements from fetal liver, fetal bone marrow, and naive peripheral blood, all of which involved invading and recipient V(H)4 genes that contain a cryptic heptamer, a 13-bp spacer, and nonamer in the 5' portion of framework region 3. Surprisingly, all pseudohybrid joins lacked the molecular processing associated with typical V(H)(D)J(H) recombination or nonhomologous end joining. Although inefficient compared with a canonical recombination signal sequences, the V(H)4 cRSS was a significantly better substrate for in vitro RAG-mediated cleavage than the V(H)3 cRSS. It has been suggested that activation-induced cytidine deamination (AICDA) may contribute to V(H) replacement. However, we found similar secondary rearrangements using V(H)4 genes in AICDA-deficient human B cells. The data suggest that V(H)4 replacement in preimmune human B cells is mediated by an AICDA-independent mechanism resulting from inefficient but selective RAG activity.

Characterization of Ig gene somatic hypermutation in the absence of activation-induced cytidine deaminase.

Somatic hypermutation (SHM) of Ig genes depends upon the deamination of C nucleotides in WRCY (W = A/T, R = A/G, Y = C/T) motifs by activation-induced cytidine deaminase (AICDA). Despite this, a large number of mutations occur in WA motifs that can be accounted for by the activity of polymerase eta (POL eta). To determine whether there are AICDA-independent mutations and to characterize the relationship between AICDA- and POL eta-mediated mutations, 1470 H chain and 1313 kappa- and lambda-chain rearrangements from three AICDA(-/-) patients were analyzed. The Ig mutation frequency of all V(H) genes from AICDA(-/-) patients was 40-fold less than that of normal donors, whereas the mutation frequency of mutated V(H) sequences from AICDA(-/-) patients was 6.8-fold less than that of normal donors. AICDA(-/-) B cells lack mutations in WRCY/RGYW motifs as well as replacement mutations and mutational targeting in complementarity-determining regions. A significantly reduced mutation frequency in WA motifs compared with normal donors and an increased percentage of transitions, which may relate to reduced uracil DNA-glycosylase activity, suggest a role for AICDA in regulating POL eta and uracil DNA-glycosylase activity. Similar results were observed in V(L) rearrangements. The residual mutations were predominantly G:C substitutions, indicating that AICDA-independent cytidine deamination was a likely, yet inefficient, mechanism for mutating Ig genes.

Germline-like predecessors of broadly neutralizing antibodies lack measurable binding to HIV-1 envelope glycoproteins: implications for evasion of immune responses and design of vaccine immunogens.

Several human monoclonal antibodies (hmAbs) including b12, 2G12, and 2F5 exhibit relatively potent and broad HIV-1-neutralizing activity. However, their elicitation in vivo by vaccine immunogens based on the HIV-1 envelope glycoprotein (Env) has not been successful. We have hypothesized that HIV-1 has evolved a strategy to reduce or eliminate the immunogenicity of the highly conserved epitopes of such antibodies by using "holes" (absence or very weak binding to these epitopes of germline antibodies that is not sufficient to initiate and/or maintain an efficient immune response) in the human germline B cell receptor (BCR) repertoire. To begin to test this hypothesis we have designed germline-like antibodies corresponding most closely to b12, 2G12, and 2F5 as well as to X5, m44, and m46 which are cross-reactive but with relatively modest neutralizing activity as natively occurring antibodies due to size and/or other effects. The germline-like X5, m44, and m46 bound with relatively high affinity to all tested Envs. In contrast, germline-like b12, 2G12, and 2F5 lacked measurable binding to Envs in an ELISA assay although the corresponding mature antibodies did. These results provide initial evidence that Env structures containing conserved vulnerable epitopes may not initiate humoral responses by binding to germline antibodies. Even if such responses are initiated by very weak binding undetectable in our assay it is likely that they will be outcompeted by responses to structures containing the epitopes of X5, m44, m46, and other antibodies that bind germline BCRs with much higher affinity/avidity. This hypothesis, if further supported by data, could contribute to our understanding of how HIV-1 evades immune responses and offer new concepts for design of effective vaccine immunogens.

B-cell repertoire and clonal analysis in unaffected first degree relatives in familial chronic lymphocytic leukaemia kindred.

Monoclonal B cell lymphocytosis (MBL) was detected in four unaffected first-degree relatives (FDR) in a familial chronic lymphocytic leukaemia (CLL) kindred. The proband remains untreated and two male siblings have died. The four unaffected siblings have been followed for a five-year period. All four FDR developed a kappa(+)CD5(+) MBL detected by flow cytometry. Poymerase chain reaction (PCR) for IGHV rearrangement showed evidence of oligoclonality in three of these individuals. Single cell PCR of flow cytometric sorted kappa(+) cells combined with Ig kappa light chain gene sequencing revealed further evidence of monoclonality in two of these individuals. Three of these individuals all showed evidence of hyper-somatic mutations. The B-cell repertoire in unaffected FDR in familial CLL offers a new area to investigate the interface between the immune system and lymphoid neoplasm.

Developmental Pathway of the MPER-Directed HIV-1-Neutralizing Antibody 10E8.

Antibody 10E8 targets the membrane-proximal external region (MPER) of HIV-1 gp41, neutralizes >97% of HIV-1 isolates, and lacks the auto-reactivity often associated with MPER-directed antibodies. The developmental pathway of 10E8 might therefore serve as a promising template for vaccine design, but samples from time-of-infection-often used to infer the B cell record-are unavailable. In this study, we used crystallography, next-generation sequencing (NGS), and functional assessments to infer the 10E8 developmental pathway from a single time point. Mutational analysis indicated somatic hypermutation of the 2nd-heavy chain-complementarity determining region (CDR H2) to be critical for neutralization, and structures of 10E8 variants with V-gene regions reverted to genomic origin for heavy-and-light chains or heavy chain-only showed structural differences >2 Å relative to mature 10E8 in the CDR H2 and H3. To understand these developmental changes, we used bioinformatic sieving, maximum likelihood, and parsimony analyses of immunoglobulin transcripts to identify 10E8-lineage members, to infer the 10E8-unmutated common ancestor (UCA), and to calculate 10E8-developmental intermediates. We were assisted in this analysis by the preservation of a critical D-gene segment, which was unmutated in most 10E8-lineage sequences. UCA and early intermediates weakly bound a 26-residue-MPER peptide, whereas HIV-1 neutralization and epitope recognition in liposomes were only observed with late intermediates. Antibody 10E8 thus develops from a UCA with weak MPER affinity and substantial differences in CDR H2 and H3 from the mature 10E8; only after extensive somatic hypermutation do 10E8-lineage members gain recognition in the context of membrane and HIV-1 neutralization.

Isolation of human monoclonal antibodies from peripheral blood B cells.

Isolation of monoclonal antibodies is an important technique for understanding the specificities and characteristics of antibodies that underlie the humoral immune response to a given antigen. Here we describe a technique for isolating monoclonal antibodies from human peripheral blood mononuclear cells. The protocol includes strategies for the isolation of switch-memory B cells from peripheral blood, the culture of B cells, the removal of the supernatant for screening and the lysis of B cells in preparation for immunoglobulin heavy-chain and light-chain amplification and cloning. We have observed that the addition of cytokines IL-2, IL-21 and irradiated 3T3-msCD40L feeder cells can successfully stimulate switch-memory B cells to produce high concentrations of IgG in the supernatant. The supernatant may then be screened by appropriate assays for binding or for other functions. This protocol can be completed in 2 weeks. It is adaptable to use in other species and enables the efficient isolation of antibodies with a desired functional characteristic without prior knowledge of specificity.

Comparison of antibody repertoires produced by HIV-1 infection, other chronic and acute infections, and systemic autoimmune disease.

BACKGROUND: Antibodies (Abs) produced during HIV-1 infection rarely neutralize a broad range of viral isolates; only eight broadly-neutralizing (bNt) monoclonal (M)Abs have been isolated. Yet, to be effective, an HIV-1 vaccine may have to elicit the essential features of these MAbs. The V genes of all of these bNt MAbs are highly somatically mutated, and the V(H) genes of five of them encode a long (≥ 20 aa) third complementarity-determining region (CDR-H3). This led us to question whether long CDR-H3s and high levels of somatic mutation (SM) are a preferred feature of anti-HIV bNt MAbs, or if other adaptive immune responses elicit them in general. METHODOLOGY AND PRINCIPAL FINDINGS: We assembled a V(H)-gene sequence database from over 700 human MAbs of known antigen specificity isolated from chronic (viral) infections (ChI), acute (bacterial and viral) infections (AcI), and systemic autoimmune diseases (SAD), and compared their CDR-H3 length, number of SMs and germline V(H)-gene usage. We found that anti-HIV Abs, regardless of their neutralization breadth, tended to have long CDR-H3s and high numbers of SMs. However, these features were also common among Abs associated with other chronic viral infections. In contrast, Abs from acute viral infections (but not bacterial infections) tended to have relatively short CDR-H3s and a low number of SMs, whereas SAD Abs were generally intermediate in CDR-H3 length and number of SMs. Analysis of V(H) gene usage showed that ChI Abs also tended to favor distal germline V(H)-genes (particularly V(H)1-69), especially in Abs bearing long CDR-H3s. CONCLUSIONS AND SIGNIFICANCE: The striking difference between the Abs produced during chronic vs. acute viral infection suggests that Abs bearing long CDR-H3s, high levels of SM and V(H)1-69 gene usage may be preferentially selected during persistent infection.

Focused evolution of HIV-1 neutralizing antibodies revealed by structures and deep sequencing.

Antibody VRC01 is a human immunoglobulin that neutralizes about 90% of HIV-1 isolates. To understand how such broadly neutralizing antibodies develop, we used x-ray crystallography and 454 pyrosequencing to characterize additional VRC01-like antibodies from HIV-1-infected individuals. Crystal structures revealed a convergent mode of binding for diverse antibodies to the same CD4-binding-site epitope. A functional genomics analysis of expressed heavy and light chains revealed common pathways of antibody-heavy chain maturation, confined to the IGHV1-2*02 lineage, involving dozens of somatic changes, and capable of pairing with different light chains. Broadly neutralizing HIV-1 immunity associated with VRC01-like antibodies thus involves the evolution of antibodies to a highly affinity-matured state required to recognize an invariant viral structure, with lineages defined from thousands of sequences providing a genetic roadmap of their development.

Rational design of envelope identifies broadly neutralizing human monoclonal antibodies to HIV-1.

Cross-reactive neutralizing antibodies (NAbs) are found in the sera of many HIV-1-infected individuals, but the virologic basis of their neutralization remains poorly understood. We used knowledge of HIV-1 envelope structure to develop antigenically resurfaced glycoproteins specific for the structurally conserved site of initial CD4 receptor binding. These probes were used to identify sera with NAbs to the CD4-binding site (CD4bs) and to isolate individual B cells from such an HIV-1-infected donor. By expressing immunoglobulin genes from individual cells, we identified three monoclonal antibodies, including a pair of somatic variants that neutralized over 90% of circulating HIV-1 isolates. Exceptionally broad HIV-1 neutralization can be achieved with individual antibodies targeted to the functionally conserved CD4bs of glycoprotein 120, an important insight for future HIV-1 vaccine design.

Effective therapy for nephritis in (NZB x NZW)F1 mice with triptolide and tripdiolide, the principal active components of the Chinese herbal remedy Tripterygium wilfordii Hook F.

OBJECTIVE: Triptolide and tripdiolide are thought to be active components of the Chinese antirheumatic herbal remedy Tripterygium wilfordii Hook F, which has been shown to be effective in treating murine lupus nephritis. This study was undertaken to examine the therapeutic effect of triptolide and tripdiolide on established lupus nephritis in (NZB x NZW)F1 mice. METHODS: (NZB x NZW)F1 mice were treated with vehicle, triptolide, or tripdiolide for 15 weeks beginning at the age of 29 weeks (after the development of lupus nephritis). Body weight, proteinuria, and anti-double-stranded DNA (anti-dsDNA) antibodies were monitored, and the kidney and spleen were assessed histologically. Culture supernatants of spleen mononuclear cells were assayed for cytokines. RESULTS: By 28 weeks, most (NZB x NZW)F1 mice had developed lupus nephritis. Vehicle-treated mice exhibited progressive proteinuria, hypoalbuminemia, elevated blood urea nitrogen (BUN) levels, and evidence of severe nephritis. In contrast, proteinuria and BUN levels were significantly reduced in mice treated with either triptolide or tripdiolide as compared with those treated with vehicle. There was no hypoalbuminemia or apparent evidence of lupus nephritis in mice treated with either of the 2 diterpenoids. At 44 weeks of age, the survival rate in mice treated with vehicle (35.7%) was markedly lower than that in mice treated with either triptolide (87.5%) or tripdiolide (88.2%). The mean level of anti-dsDNA antibody in mice treated with tripdiolide was lower than that in the vehicle-treated mice upon completion of the treatment course. Production of tumor necrosis factor, interleukin-6, and monocyte chemoattractant protein 1 by spleen cells was also decreased after diterpenoid therapy. CONCLUSION: Therapy with triptolide or tripdiolide significantly ameliorated lupus nephritis in (NZB x NZW)F1 mice, reduced cytokine and chemokine production, and prolonged survival.