new concepts in immunodeficiency diseases

-.e es ,ree ur s immunology Toaay, Vol. I I, No I0 1990

T~e s'u~: of ~nma:y ~mmunodeficienoes ~as, ~n d~e past, conmbutod greatly to kno~#~,eotge of the intact immune sy.~tem. Mor~ re~en~ tn:s process ha~ ~een re- versed, r~dt#ng in an explosion of new #n~rmation on ~he nature of prima~ immune defecta, tn this summan/ of the Jeffrey Model/~vmoosium*, Sudhir Gupta gives a syndrom~oy-syndrome accoun~ of t,he latest developments.

Tgt~l &,ffidendes Atain Fischer (Hopital Necker-

Enfante Malades, Paris) reviewed th:ee T-cell membrane immuno- def'ciencies, includipg leucocyte adhesion deficiency (LAD), immunodeficiency associated with low expression of the CD3-T-ceI! receptor ~TCR) complex, and the immuno- defioency associated with eosino- phiiia (Omenn's synd, ome).

LAD is an autosomal recessive (AR) disorder of the expression of leucocyte associated functional antigen-1 (LFA-1L The syndrome can be sub- d;vided into moderate and severe b, pes, based on decreased and com- plete lack of expression of LFA-1, re- spectively. In the former case, LFA-1 can be upregulated by gamma- interferon (IFN-~/). Most of the clinical manifestations are consequences of phagocy ;.ic cell adhesion defects. The T-cell deficiency is relatively mild, and most T-cell functJons are norma!, aq exception being the decreased o/totoxic T-cell responses; however, viral infections are infrequent. There is decreased help from CD4 ÷ T cells for B cells, apparently due to poor conjugation. However, this defect is partly compensated for by the CD2- LFA-3 mechanism.

in CD3-TCR complex immune- deficiency, CD3-,/6~ chain expression is defective, but the (~ chain expression is normal. The loss of expression appears to be due to defective regulation.

Omenn's syndrome is charac- terized by infiltration of skin and gut mucosa with CD25--activated T cells. There is an increased proportion of ~/6 T cells and the ~IB T cells show restricted heterogeneity,, with pre- dominant rearrangement of the C~1 and C~2 genes. Although T cells are found in large quantities in skin and gut, the numbers of T cells in skin and thymus are reduced. ",~.e fTrst Jeffrey M0dell Syrnpos~urn was held at Mount S~nai School of Medlcin~, New York, on 18-19 Apr,! 19~.

New concepts in imrnunodeficiency diseases from Sudhir Gupla

Raif Geha (Harvard Medical School, Boston) described a patient with T-cell deficiency who had a fail- ure in cytokine transcriptmon. T- and B-cell phenotypes were normal but the T cells did not respond to phyto- haemagglutinin (PHA) nr anti-CD3. Phorbol myristate aceta*,e (PMA) and ionomycin failed to correct the defect. Messenger RNA (mRNA) for in- terleukin 4 (IL-4) and IL-5 were absent and mRNA for IL-2 and !L-3 were marlcedly reduced. Although the pre- cise mechanism of the defect is unclear, a defect in regulatory nuclear binding proteins/factors was pro- posed. A second patient with a primary B-cell defect and hypogammaglobulinemia was described, in this individual all B cells expressed both surface immunoglobulin M (slgM) and slgD, and more than 85% of B cells expressed CD23. In vitro IgM, but not IgA or IgG, synthesis was observed, suggesting a switch defect, and indeed the B cells were deficient in recombinase activity.

B-cell deficiencies Differentiation and development

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Palo Alto) described the first long- term in vitro system for studying human B-lymphoid cell differentiation. Fetal bone marrow, adult bone marrow and fetal liver cells gave rise to B ce!!s for up to five inonths. The assay involves culturing human hematopoietic cells on a mouse bone-marrow stromal cell line (SYS-1) derived from a BALB/c long- term Whitlock-Witte culture. CD34 ÷ CD10-CD19-CD20- CO3- bone- marrow cells give rise to CD10 ÷ CD19+CIz + B cells for at least three months, with an overall increase of 30-500-fold. A small (1-10%;, but significant, proportion of CD19 + cells express slgM bearing K and ", hght chains, indicating that the cells are not monoclonal. The CD34+CD10+CD19 + cells survive for only three to four weeks, with only a two- to five-fold increase in cell numbers. Baum and colleagues are investigating the Ig repertoire of long-term cultured B cells. This long- term culture assay should be useful in the study of growth and develop-

ment of human B cells in physiologi- cal and pathological states.

Antibody genes are assembled from a series of germline gene segments that are juxtapased during the maturation of B lymphocytes. Al- though diversification of the adult antibody repertoire results mainly from tile combinatorial joining of these segments, a restricted set of antibody heavy chain variable (V,#), diversity (DH), and joining U~,) region gene segments appear preferen- tially in the human fetal repertoire. Roger Perlmutter (Univ. Washington, Seattle) discussed the finding that one of these early-expressed VH el- ements (VHC) is the most 3' VH gene segment, positioned //RHobases on the 5' side of the JH lOCUS and im- mediately adjacent to a set of pre- viously described DH sequences. These findings were extended to include results for several early fetal livers, in extrapolating the gene sequences to provide potential antibody structures, remarkable struc- tural similarities were observed in the Fab regions outside the binding ske that may lead to broad cross reactive h i n , - i i n , - , r~=++~r , ' ,c -f,-,r +h~ , ~,/÷;i.,,._,.li,,~ i ~J l l I1L,/III | ~ j ~ ,~1 L g ~ I I i_1 1 I,~11 LI l~T Gill 1 L | I L , I ~ J U I ~ . , ~

produced. Lloyd Mayer (Mount Sinai School

of Medicine, Now York) described a B-ce[! differentiation factor (BCDF) produced by 1 cells, and identified its receptor. This factor has a molecular weight of 32 kDa, is distinct from IL-6 in molecular weight and isoeiectric point, and is not neutralized or pre- cipitated by anti-lL-6 antibody. -[his factor can be used to identify a 46 kOa receptor that is distinct from the IL-6 receptor (80 kDa). Antibody to BCDF does not inhibit pokeweed mitogen (PWM)-induced Ig synthesis, whereas anti-lL-6 antibody does. Per- tussis toxin inhibits BCDF effects, G proteins therefore appear to be involved in BCDF action.

Aspects of B-cell activation Guanosine nucleotides derivatized

either at C8 or at both N7 and C8 are very powerful stimulators of the immune system. They updergo facili- tated transport into the cytoplasmic compartment of the cell and act in- tracellularly, bypassing the biochemi-

~ t990, Elsevier Science Pubhshers Lid, UK 0!67--4919/90/$02 00

Immunology Today, Vol. 11, No 10 1990

cal steps involved in membrane signal transduction. Sudhir Gupta (Univ. California, Irvine) reviewed the immunological properties of di- substituted guanosine nucleotides derivatized at N7 and C8 (7-methyl 8-oxo) They transmit a T-cell-like differentiation signal to B cells, enabling them to respond to T-cell-dependent antigens in the absence of T cells. They increase the efficacy ut helper T cells and increase cytokine production (IFN-3, by T cells and IL-1 by macrophages). These compounds have been successful in restoring immune responsiveness in a variety of murine models of humotal immunodeficiency. Gupta presented data from a study done in collaboration with Michael Goodman and William Weigle (Scripps Clinic and Research Foundation, La Joila) demonstrati:qg in vitro restoration of antigen specific antibody responsiveness (IgM)in all nine patients with common variable immur'odpfici~ncy studies These effects were independent of the protein kinase C pathway. The data on the target compound, the 7-allyt 8-oxo guanosine, show similar immunological activities. In humans this compound causes depolarization of the plasma membrane, decreases intracellular pH and enhances the ant i body response to tetanus toxoid. It also induces the production of IL-1 by human monocytes, although the magnitude of response is small in comparison with lipopolysaccharide. Studies are in progress to examine the effect of this compound on specific IgM and IgG responses in patients with common variab!e immunodeficiency and clinical trials are anticipated in the near future.

Immunoglobufin deficiencies Lars Hanson (University of

Goteborg, Sweden) emphasized the need for Improving the standardiz- ation of techniques that are current!y being used for the measurement of IgG subclasses. The measu,ement of IgG4 subclass is especially difficult. He emphasized that IgG subclass deficiencies occur in pairs. IgG1 and IgG3 together and IgG2 and IgG4 together. Furthermore, IgG subclass deficiency may not be stable; a patient presenting with one subclass deficiency may develop additional subclass deficiency or switch to different subclass deficiency. Therefore, patients with IgG subclass deficiency should be .nonitored for changes.

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Age appears to influence the type of tgG subclass deficiency, possibly suggesting a hormonal influence. In children, the male:female ratio of IgG subclass deficiency is 3:1, whereas in adults the ratio is i:3. Clearly, more data are needed to establish the mechanism and clinical relevance of IgG ~ubclass deficiency.

There is high frequency of null al- lele, at one or more C4 loci !n patients with selective IgA deficiency. Since cotr,,mon variable immunodeficiency (CV~) patients have similar defects, it is Fossible that s~Jme aspect of Ig synthesis could be controlled by loci in the MHC. Charlotte Cunningham- Rundles (Mount Sinai School of Medicine, New York) showed that approximately half of a group of IgA- deficient individuals tqave one or n~ore null alleles, and that ,,~ addition to the linkage with HLA-A1, -B8 and DR3 alleles, a linkage with HLA-B38 can be demonstrated. Patients with IgA deficiency and tgG subclass deficiencies were often found to have null alleles. It also appears that IgA- deficient individuals with C4a null alleles clear circulating immune complexes more slowly than those not lacking these complement proteins. This was to be expected since C4a 0inds immune complexes better than C4b.

X-linked diseases Between one-third and one-half of

all males with severe combined immunodeficiency (SClD) and no family history of immunodeficlency represent the first manifestation in their family of a new mutation of the gene that causes X-linked SCID (Mary Ellen Conley, St Jude Children's Re- search Hospital, Memphis). These patients, like boys with a positive family history of X-linked SCtD, have markedly reduced numbers of T lymphocytes, elevated numbers of B lymphocytes and hypogammaglobuhn- emia. The hypogammaglobulinemia is due, in part, to the expression of the gene defect in B cells as well as in T cells. Patients with X-linked SCID who are treated with bone marrow transplant tend to engraft T cells readily but require cytoreductive therapy prior to transplant for B-cell engraftment. B-cell function after transplants tends to be poor, even in patients who have received the transplant from HLA-matched siblings. Bet- ter transplant strategies are required to achieve optimum long-term results.

Richard Gatti (UCLA, Los Angeles) reviewed the 9ene~.ics of ataxia telangiectasia (AT). In 19£8, ihe gene for AT compiementation grc,_:p A was linked to two genetic markers on the long arm on chromosome 11a22-23. !n follow-up studies, the AT gene was placed in a 21 cent~- morgan (cM)interval defined by stromelysin and s144. Gatti reviewed the data from an israeli p~digree ar,d a Japanese group and qugg~-sted that the AT locus can be furtt-er localized to a 7 cM region.

R.K.B. Schuurman (Umv. Medical Center, The Netherlands) described a differentiation arrest at pre- ~.qd pro- B cell level in patients w:.th X-linked agammaglobulinaemia (X-LA). In this condition most B cells express heavy chain without a variable segment although Epstein-B&; vtrus (EBV)- transformed lines shcw normal VDJ rearrangement. Thus it I~ unlikely that there is a recombinase defect and T cells appear not to be involved. The Y-LA gene is linked to the q22 area of X chromosome. The disease has full penetration.

Claude Griscelli (Hopital Necker Enfant Malades, Paris) discussed a severe immunodeficiency disorder associated with MHC class II deficiency. The MHC class II molecules a~ e deficient in a variety of cells including B cells, monocytes, acti- v,~t~el T rpll~ ~nd I~nnerhan~ cell

MHC class I, CD3, TCR a~l~ and TCR ~/.~ expression is normal; however, there is a marked decrease in CD4* T cells. There is an apparent absence of and 13 polypeptides of DR, DP, and DO class II molecules due to abnormal regulation cf class II molecules. An abnormal transactive pleiotropic regulatory gene is located outside the MHC and the two prominant DNAse I-hypersensitive sites in the H~J3,-DR promoter are absent in B cells, suggesting an abnormal binding of regulatory proteins.

Fred Rosen (Harvard Medical School, Boston) pointed out that sialophorin, which is phenotypically de- ,'-ective on lymphocytes from patients with Wiskott-Aldrich Syndrome (WAS), is a componen[ of a T-lymphocyte activation pathway. The human sialophorin has recently been cloned the amino acid sequence pre- dicts an integral membrane po',ypep- tide comprising an amino-terminal hydrophobic region followed by an extracellular region that has a uni- form distribution of numerous serine,

345

a.d {e iures threonine and proline residues, a transmembrane region and a c3rboxy-termmal intracellular region. The transmembrane and intracellular regions have been highly conserved during evolution and the intraceilular region contains a number of phos- phorylation sites that might mediate signal transduction. Since WAS is X-lir, ked and sialophorin is encoded on chromosome ~6, it has been suggested that the chromosome locus on the short arm of the X-chromosome may control the expression of sialophorin on cell sur- faces. Interestingly, splenectomy in WAS has no effect on the expression of sialophorin.

The pathogenesis of hereditary angioedema remains unclear. The major development in this disease has been its treatment with impeded androgens which increase plasma C I inhibitor levels, presumably directed by the one normal gene present in such pa[ients. Clinical trials with IFN-~/, which can also upregulate synthesis of CI inhibitor, and with puff- fled C I inhibitor, are under way.

John Gallin (NIAID, NIH, Bethesda) discussed the recent advances in chronic granulomatous disease (CGD), a disease whic~ is X-linked in 60%, autosomal recessi"e (AR) in 35% ~nd autosomal dominant in less than I% of cases. X-linked CGD is associated with an absence or ab: HgillldilLy (..,1i [13~ ~ I KL~a c n a l n OT

cytochrome B, whereas in AR CGD there is a lack of, or abnorm,-.,,3 .... the 22 kDa chain. Recently, 47 and 65kDa neutrophil cytoplasmic factors (NCF) have been cloned. These factors are highly positively charged, rich in arginine, bind to carboxylic terminal of cytochrome B and ~rans- locate to the membrane. The 47 kDa NCF is absent in 35% of AR CGD and the 65 kDa is absent in 5% of AR

- ~ CGD patients. In v/tro, recombinant

47 kDa protein reconstitutes the PMN from CGD for superoxide generation. Also in vitro, IFN--y augments superoxide generation, induces 47 kDa NCF mRNA and amplifies both 47 and 91 kDa protein synthesis. In vivo, in a double-blind control placebo trial, IFN-~/ has produced remarkable re- suits in CGD: a significant reduction in primary and recurrent infections ~nd 72% reduction in the relative risk of serious infection. No antibodies to IFN-~/were observed. Food and Drug Administration approval for the us~. of IFN-~/in CGD is anticipated. Further therapeutic approaches for CGD, be- sides IFN-~t and its inducers, include replacement of missing proteins and gene therapy.

Therapy Thomas A. Waldmann (National

Cancer Institute, NIH, Bethesda) discussed the potential of IL-2 receptor- directed therapy in a variety of immunodeficiencies and malignancies. These included adult T-cell leukemia (ATL), cutaneous T-cell lymphomas, rheumatoid arthritis, systemic lupus erythematosus, type I diabetes m~:!;t,,:, and tropical spastic paraparesis, ,, distant cousin of multiple sclerosis that is associated with nonclonal integration of HTLV-1 in CD4 ÷ T cells. In ATL, remission has lasted for 2-11 months, immuno- deficien~ has been corrected,/ck dis- appears, ou~ anomer tyrosme Kmase appears in CD4 ÷ T-cells, resulting in resistance to unmodified anti-lL-2 receptor (anti-Tac) therapy. Preliminary results in human cardiac aliograft are encouraging; however, a humoral response to mouse Ig is observed. It is crucial, therefore, that the hyper- chimeric or humanized monoclonal antibodies are produced and used to circumvent these problems.

Richard O'Reilly (Memorial Sloan- Kettering Cancer Center, New York)

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Immunology Today. Vol. 1 I. No 10 1990

discussed different approaches to bone marrow transplantation in SCID patients lacking a sibling donor. These techniques involve depletion of T cells from the donor marrow using soyabean lectin plus E-rosette depletion, multiple E-rosette depletion, soyabean lectin plus immunomagnetic separation, mouse anti-CD2 and CD8 plus rabbit complement, anti- CD5 immunotoxin ricin A, anti-CD3 and anti-CD8 immunomagnetic separation and rat monoclonal antibody (CAMPATH-1) plus human complement. Adenosine-deaminase- deficient (ADA-) SCID patients show poorer engraftment than ADA ÷ SCID. Cytoreduction improves engraftment in ADA ÷ SCID. The most important factor for engraftment is the presence of natural killer cells. Lack of B-cell engraftment remains a puzzle.

R. Michael Blaese (NCI, NIH, Beth- esda) reviewed gene transfer t~ch- niques. He discussed the ,,=e of lymphocytes as a vehicle for gene therapy. It has the advantages that lymphocytes can be maintained in culture, can be used for serial gene transfer, and allow time to test pepu- lation safety. Monkey bone marrow cells treated with ADA vector resulted in the synthesis of human ADA by the monkey; however, the response was transient. The ADA gene is also expressed, and persists, in murine lymphocytes. The Food and Drug Administration of the US has just ap- proved the use of ADA gene therapy in human ADA-SCID. Human studies are anticipated in the near future for the treatmpnt of ADA- SCID. Gene transfer techniques have also been used in non-genetic diseases. Tumor infiltrating lymphocyte (TIL) treatment results in 50% success in cer- tain malignancies. No correlation has so far been observed between TIL phenotype and response to treatment. TILs have been modified with a genn encoding neomycin resistance and this unique DNA marker has been used to follow the survival and distribution of TIL. Six patients have been treated with n,o side effects at up to 300 days and TILs ha'-e been recovered up to !85 days after ~n- fusion. TILs can be made more effec- tive by inserting a gene for a cytokine such as tumour necrosis factor.

Sudhir Gupta is at the Division of Clinical and Basic Immunology. University of California, Irvine, CA 92777, USA.

new concepts in immunodeficiency diseases

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