Anticardiolipin autoantibodies in serum samples and cryoglobulins of patients with chronic hepatitis C infection

OBJECTIVE

Chronic hepatitis C virus (HCV) has been linked to extrahepatic autoimmune phenomena. In addition, a variety of autoantibodies are found in patients with HCV. The prevalence, nature, and clinical significance of anticardiolipin (aCL) autoantibodies in serum samples of patients with HCV were therefore investigated.

PATIENTS AND METHODS

A prospective study of 48 consecutive patients with chronic HCV with no evidence of previous hepatitis B virus (HBV) infection or any other autoimmune disorder. Thirty patients with HBV and 50 healthy volunteers matched for age and sex served as control groups. Anticardiolipin antibodies in the serum samples and cryoprecipitates were measured by a sensitive enzyme linked immunosorbent assay (ELISA). The beta(2) glycoprotein I (beta(2)-GPI) dependency was determined by carrying out aCL assays in the presence or absence of fetal calf serum samples.

RESULTS

High levels of IgG aCL antibodies were detected in serum samples of 21/48 (44%) patients with HCV. These autoantibodies showed no beta(2)-GPI dependency. The control groups had much lower levels of aCL antibodies (20% in the patients with HBV and none in the normal volunteers). Cryoprecipitates from four patients with HCV (three aCL positive; one aCL negative) were further isolated. In two of the three aCL positive patients, specific cardiolipin reactivity was shown in the cryoprecipitates. The group of patients with HCV and aCL antibodies in their serum showed significantly higher total IgG levels, a higher incidence of antinuclear antibodies, and viraemia (HCV RNA) than the aCL negative patients. None of the patients with HCV and aCL antibodies showed any clinical manifestations related to those autoantibodies.

CONCLUSIONS

This study clearly shows a high prevalence of IgG aCL antibodies in the serum of patients with HCV and the localisation of these antibodies in some cryoprecipitates. The role of these autoantibodies on the course of HCV infection and their clinical significance has not yet been determined.

Spontaneous bacterial arthritis in a cirrhotic patient

Septic arthritis is usually of hematogenous origin and is increasingly being reported in elderly patients, who often have underlying medical conditions such as diabetes or alcoholism. We report a 62-year-old patient with alcoholic liver disease who presented with Escherichia coli bacteremia and septic arthritis in a previously fractured ankle. There are scarce reports of infectious arthritis in cirrhotic patients, but this is the first report of arthritis after a primary enteric bacteremia. We believe that the patient described here developed E. coli bacteremia as a result of bacterial overgrowth and translocation related to alcoholic liver disease and cirrhosis. The resulting bacteremia resulted in the development of infection in the left ankle, which had preexisting disease and was thus vulnerable. This case provides further evidence for the mode of infection being bacteremia in cirrhotic patients. In patients with cirrhosis and fever, a high index of suspicion is required for joint infection as a potential cause of fever or deterioration in the cirrhotic's patient general condition.

Celiac sprue presenting during the puerperium: a report of three cases and a review of the literature

We present three patients in whom there was an acute presentation of malabsorption in the puerperium and in whom the final diagnosis was celiac sprue. The reason for the dramatic increase in the symptoms after delivery, as well as the absence of symptoms before this, is unclear but may be related to immunologic changes that occur during pregnancy.

Zygomycotic gangrenous cellulitis in a patient with non-insulin dependent diabetes mellitus

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Severe cholestatic hepatitis following cloxacillin treatment

We describe a 77-year-old woman who developed fatigue, fever, a maculopapular rash and severe cholestatic hepatitis two weeks after receiving cloxacillin and ofloxacin.

Nitric oxide: a mediator in anaphylactic shock in guinea-pigs

In this study we show that the pathophysiology of anaphylaxis includes generation of nitric oxide (NO), a very powerful, short-acting vasodilator. Guinea-pigs sensitized to ovalbumin were treated with 200 microgram/kg diphenylene iodonium (DPI), and NO synthase inhibitor, prior to antigen challenge. Mortality following the challenge fell from 71 to 39% (p < 0.001, n = 59). In the Langendorff preparation perfused isolated hearts from sensitized guinea-pigs were challenged to initiate cardiac anaphylaxis. The coronary flow rate (CFR), a direct reflection of coronary arterial resistance, was reduced by antigen challenge to 56 +/- 4% (n = 16) of the basal rate. DPI (2 micrograms/ml) intensified the antigen-induced fall in CFR to 13 +/- 3% of control (p < 0.005, n = 5), and the false substrate for NO, L-N-methylarginine, to 37 +/- 3% (p < 0.05, n = 4). Sodium nitroprusside (SNP), a NO generator, raised the basal CFR by 46% (from 11.2 +/- 1.7 ml/min to 16.3 +/- 1.9 ml/min) and blunted the antigen-induced fall in CFR. Paradoxically, DPI, which can inhibit flavoprotein enzymes other than NO synthase, potentiated the vasodilator effect of SNP, raising the basal CFR by 116%. Together these results strongly indicate that the vasodilator NO is generated in anaphylaxis. However, whereas in the heart it may function as a counterweight to the vasospasm of the coronary arteries, in the intact animal it appears to be a major contributor to the potentially lethal hypotension of anaphylactic shock.

Enterococcal endocarditis after extracorporeal shock wave lithotripsy for nephrolithiasis

We report a case of enterococcal endocarditis following extracorporeal shock wave lithotripsy (ESWL) for ureteral stone. Although endocarditis following ESWL is very rare, transient bacteraemia occurs during ESWL. This case is a reminder that enterococcal endocarditis may follow innovative genitourinary procedures without appropriate prophylaxis.

Sjögren's syndrome presenting as hypokalemic paralysis due to distal renal tubular acidosis

A 57-year-old woman presented with a flaccid paralysis, muscle tenderness, and respiratory depression. Laboratory results demonstrated severe hypokalemia with hyperchloremic metabolic acidosis and abnormally acidified urine. The urinary anion gap was positive in the presence of acidemia, thus establishing the diagnosis of distal renal tubular acidosis (DRTA). The patient fully recovered after potassium and alkali replacement. Further investigation revealed Sjögren's syndrome as the underlying cause of DRTA.

Correlation between gold-induced enterocolitis and the presence of the HLA-DRB1*0404 allele

OBJECTIVE

In recent years we have treated 4 rheumatoid arthritis (RA) patients who developed gold-induced enterocolitis, a well-recognized, although rare, complication of chrysotherapy. The aim of the present study was to seek any genetic predisposition for this complication.

METHODS

HLA DNA typing was done on fresh white blood cells from the 4 patients.

RESULTS

Three of the 4 patients (75%) exhibited the DRB1*0404 allele, whereas the prevalence of this allele among the Ashkenazi Jewish population of RA patients without colitis was 9.2% and 10.2% in 2 different studies.

CONCLUSION

The results indicate that the DRB1*0404 may be associated with risk for the development of gold-induced enterocolitis in this population and suggest that HLA DNA typing should be considered in Jews who may be undergoing chrysotherapy.

Effect of acute cytomegalovirus infection on drug-induced SLE

A 58 year old woman developed systemic symptoms, interstitial lung disease, splenomegaly, leukopenia and anti-histone and anti-nuclear antibodies (ANA), while treated with hydralazine for hypertension. Five months after presentation she was admitted with high fever, skin rash and atypical lymphocytosis due to acute cytomegalovirus (CMV) infection. Worsening leukopenia and increased ANA were found, and high titres of anti-DNA antibodies, anti-cardiolipin antibodies and rheumatoid factors appeared. Hydralazine was stopped and the patient gradually became asymptomatic. All autoantibodies spontaneously disappeared (over 16 weeks), and the white cell count and spleen size became normal. The patient was found to be a slow acetylator and to have both HLA-DR4 and selective IgA deficiency. Thus, a multifactorial genetic susceptibility to develop drug-induced lupus was brought out in stages first by hydralazine and then by CMV, yet all manifestations and autoantibodies resolved spontaneously, demonstrating the complex interplay of varied environmental factors with a genetic predisposition in the pathogenesis of autoimmunity.

Acute renal failure complicating organophosphate intoxication

Organophosphates are an extremely uncommon cause of acute renal failure. The mechanism is unknown. We present a case and refer to earlier reports.

The role of anticardiolipin autoantibodies in the pathogenesis of autoimmune hemolytic anemia in systemic lupus erythematosus

OBJECTIVE

To elucidate the role of anticardiolipin antibodies (aCL) in the pathogenesis of hemolytic anemia in patients with systemic lupus erythematosus (SLE).

METHODS

Immunoglobulins (Ig) and cardiolipin reactivity were evaluated in red blood cell (RBC) eluates and in the sera of patients with SLE and controls by a solid phase enzyme linked immunosorbent assay.

RESULTS

aCL were detected in sera of 2 patients with SLE with active hemolytic anemia. The RBC eluates of these patients contained Ig (mainly IgG) with significant cardiolipin reactivity. RBC eluates from healthy volunteers failed to demonstrate measurable amounts of Ig whereas Ig eluted from RBC of chronic lymphocytic leukemia patients with active hemolysis but no aCL did not react with cardiolipin. Furthermore, under treatment, one patient went into complete remission with resolution of the hemolysis, negative Coombs' tests and lower serum aCL. The other patient, however, continued to demonstrate both high sera aCL and positive Coombs' tests.

CONCLUSION

aCL may play a direct role in the pathogenesis of hemolytic anemia in some patients with SLE by acting as anti-RBC autoantibodies.

Mechanism of autoimmune hemolytic anemia in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a malignant clonal expansion of CD5+B lymphocytes. The CD5+B lymphocytes have been postulated to produce autoantibodies. CLL patients may demonstrate features of autoimmunity including autoimmune hemolytic anemia. However, the origin of the autoantibodies causing the hemolysis is not clear. The present studies were performed to determine whether these autoantibodies are the products of the neoplastic B-CLL clones. Immunoglobulins (Ig) were eluted from washed red blood cells (RBC) obtained from two CLL patients at the time they had autoimmune (DAT-direct antiglobulin test-positive) hemolytic anemia. The light chain phenotypes of these eluted autoantibodies were determined and found to be monotypic with exact correlation to the light chain expressed on the surface of the B-CLL clones. Elutions from RBC of DAT negative patients or normal volunteers failed to demonstrate measurable amounts of Ig. In contrast, Ig eluted from RBC obtained from SLE patients with DAT positive hemolytic anemia found to be polyclonal autoantibodies exhibiting both light chain types. Furthermore, CD5+B lymphocytes obtained from the same two CLL patients (DAT+) produce, in vitro understimulation with phorbal myristate acetate (PMA), monoclonal antibodies which react and bind to RBC. Thus these studies provide direct evidence demonstrating that the antibodies causing the autoimmune hemolytic anemia in our two CLL patients are the products of the B-CLL neoplastic clones.

[Subclinical renal involvement in rheumatoid arthritis]

No evidence of renal involvement was found in 104 patients with rheumatoid arthritis in routine laboratory tests, including serum creatinine, urea, uric acid, sodium, potassium, calcium, phosphorus, and urinalysis. In view of recent publications (1-9) which report renal involvement in rheumatoid arthritis, we studied 16 patients of our group (nonrandomized, 3 men and 16 women, average age 55.4 years, average duration of disease 11.9 years). We examined creatinine clearance, urinary excretion of alpha-2 microalbumin, beta-2 microglobulin, cystine, and urine concentration and acidity after a 10-hour fast. 10 patients had disturbances in 1 or more of the functions examined, in 9 of whom tubular functions were involved. In 6 there was no evidence of renal involvement. There was no correlation between renal involvement and past or present therapy, but there were direct correlations between renal involvement, duration of disease and age. Thus we found evidence for subclinical renal damage not revealed by routine laboratory tests in patients with rheumatoid arthritis. This damage should be taken into consideration when operation, examination with contrast material, or treatment with other nephrotoxic agents are being considered in these patients.

Case report: fatal seronegative rickettsial infection diagnosed by the polymerase chain reaction

A previously healthy man presented with a five day history of high fever and headache, later followed by rash and the appearance of jaundice. On the second hospital day, he suddenly developed seizures, lapsed into a coma, and died. Polymerase chain reaction (PCR) amplification revealed a 434 base pairs DNA fragment common to the genome of typhus and spotted fever group rickettsiae in the patient's blood (estimated at about 1 x 10(2) organisms/ml), and to a lesser degree in the cerebrospinal fluid. However, serological tests for rickettsiae remained negative. PCR techniques may confirm the diagnosis at an early stage, even though the rickettsemia may be minimal and the patient seronegative.

Acute oliguric renal failure complicating type A nonfulminant viral hepatitis. A case presentation and review of the literature

Nonfulminant acute renal failure very rarely complicates type A viral hepatitis. So far only eight patients have been described in the English language, Japanese, or Israeli literature who had type A viral hepatitis with renal failure without any association with "hepatorenal syndrome," pregnancy, or other types of viral hepatitis. We describe a 52-year-old man with type A viral hepatitis, proven by IgM anti-A virus antibodies complicated by oliguric renal failure, which required hemodialysis. The patient recovered completely after a few weeks. Kidney biopsy demonstrated interstitial nephritis with no glomerular involvement. Review of the literature in relation to the causes and the rarity of the renal failure is included.

Attenuation of anaphylactic shock and related mortality in guinea-pigs after administration of a potent protein kinase inhibitor, K252a

We examined whether protein kinases have a role in the expression of anaphylactic shock (AS). Guinea-pigs sensitized to ovalbumin were administered i.p. saline (control) or 10 micrograms/kg K252a, a potent protein kinase inhibitor, 30 min before challenge. The development of AS and mortality was observed for the next 2 h. In the K252a-treated group the incidence of AS fell to 53% from 100%, the maximum intensity was 62% less than the control, and mortality dropped to 16% from 50% of the animals. We suggest that protein kinases are involved in the expression of AS, and that inhibitors of these enzymes may protect against the symptoms of AS and allergy.

Mitral valve prolapse in young Israelis with thromboembolic brain disease

In order to establish the association between mitral valve prolapse (MVP) and the incidence of thromboembolic disease of the brain we reassessed 36 patients (less than or equal to 50 years old) who were hospitalized during 1983-85 because of cerebrovascular accidents. The patients underwent complete physical and neurological examinations, blood tests including coagulogram and two-dimensional echocardiogram. The control group comprised 117 patients without cerebrovascular events. In the study group, 4 patients (11.1%) had MVP compared with 10 (8.5%) in the control group. Of these four, only one male did not have any risk factor for thromboembolic event; among the other three the risk factors were systemic lupus erythematosus, hyperlipidemia, diabetes, hypertension and pregnancy. We conclude that our results are in accordance with most of the literature that MVP is not a risk factor for thromboembolic disease except in Greek and Italian populations, which are ethnically more homogeneous than other Western societies studied.

Stroke in Icelandic patients with hereditary amyloid angiopathy is related to a mutation in the cystatin C gene, an inhibitor of cysteine proteases

Cystatin C is an inhibitor of lysosomal cysteine proteases and consists of 120 amino acids. A variant of cystatin C lacking the first NH2-terminal residues and having one amino acid substitution at position 68 forms amyloid deposits mainly in the walls of brain arteries, causing fatal strokes in Icelandic patients with familial cerebral hemorrhage secondary to a form of an autosomal dominant amyloidosis. To understand the molecular basis of the genetic defect, the gene encoding cystatin C was isolated from genomic DNA libraries made from normal tissue and the brain of an Icelandic patient with hereditary cerebral hemorrhage with amyloidosis (HCHWA-I). The data indicate that the cystatin C gene encodes a polypeptide of 146 amino acids, of which the first 26 correspond to a secretory peptide signal sequence. The gene contains two intervening sequences that interrupt the coding region at amino acids 55 and 93. Comparison with genes encoding salivary cystatins and kininogen proteins show sequence homology and conservation of exon-intron structure. Except for a mutation in the second exon (CAG instead of CTG in the normal gene, resulting in the substitution of glutamine for a leucine residue), the gene cloned from the brain of the Icelandic patient is identical to the normal cystatin C gene. Thus, HCHWA-I is the first familial type of amyloidosis related to a point mutation in a gene encoding for an inhibitor. The mutation in the structural gene encoding cystatin C appears to be the primary defect in this inherited disorder causing amyloid fibril formation and accumulation followed by cerebral hemorrhage.

Fatal torsade de pointes following jaundice in a patient treated with disopyramide

A case of fatal torsade de pointes in a 53 year old patient treated with disopyramide is described. The arrhythmia followed the development of acute hepatocellular dysfunction and may have been due to failure of the liver to efficiently degrade the drug to its metabolites.

Therapeutic approaches in mixed cryoglobulinemia

In summary, one can say that, although EMCG is a perplexing and puzzling disease, and although there are more enigmas than solutions, we can establish a way of handling the disease, knowing how to divide it into benign or acute forms, and establishing a treatment attitude according to that knowledge. PP and its modifications, in combination with immunosuppressive agents, are the corner-stones to the acute form of the disease complicated by vasculitis, nephritis, chronic hepatitis and CNS involvement. Looking ahead, a new and more specific mode of treatment could emerge from our and others observations that the IgMs in the mixed cryoproteins are antiidiotypes to the IgGs. By producing autoantiidiotypes it might be possible to block some of the immune complex formation and to interfere with the cold precipitation, which is the basic pathophysiological process of essential mixed cryoglobulinemia.

Polymorphism of human immunoglobulin VH genes: a possible marker of autoimmune disease

Human DNA from 11 individuals was analysed by Southern blot for the immunoglobulin genes coding for the heavy chain variable region (VH). The analysis included two probes detecting the genes of subgroup VHII and VHIII. The VH genes pattern shows very little polymorphism whereas the VHIII genes showed a significant polymorphism. When DNA from four patients with Graves' disease was analysed, a VH band was found in DNA of all patients analysed, and of 50 per cent of SLE patients, whereas only 36 per cent of healthy people contained this VH band. This may serve as a new tool to study genetic markers of autoimmune diseases.

Systemic lupus erythematosus in 49 Israeli males: a retrospective study

Forty-nine male SLE patients, diagnosed and followed in seven medical centers in Israel between 1954 and 1983, were studied and analyzed retrospectively in order to determine whether the disease in males was clinically different from that reported in females both in Israel and in the world literature. The primary clinical and laboratory manifestations, the severity of the disease at the onset or at any time during the course of the disease, and the 1-15 year survival rates were not different from those described before in female SLE, although neurological involvement, nephritis, thrombocytopenia, vasculitis and hepatosplenomegaly were more prevalent in our series. However, more than half of the male patients (53%) had a benign course of disease characterized by long remissions requiring minimal or no medication. Long-term remission of serious renal involvement was observed completely in 14 and partially in 5 out of 33 patients. These results suggest that the male sex might alter the clinical course of SLE.

Disruption of the symphysis pubis and fatigue fractures of the pelvis in a patient with rheumatoid arthritis. A case report

A 40-year-old woman, who suffered from severe rheumatoid arthritis causing avascular necrosis of the femoral head and protrusio acetabuli of the right hip, developed a severe spontaneous disruption of the symphysis pubis concomitant with a stress fracture of the left ilium adjacent to the left sacroiliac joint. After successful total hip arthroplasty, the symphysiolysis improved, but a new stress fracture of the left superior pubic ramus developed. Fourteen months after operation both stress fractures are healed. Altered hip and pelvic girdle mechanics acting on osteoporotic bone may account for this sequence of events.

Gold-induced ileitis

We describe a patient with rheumatoid arthritis who developed severe ileitis after being treated with gold salts; the patient responded to elimination of the gold therapy and to BAL.

The effect of combination therapy (steroids, immunosuppressives, and plasmapheresis) on 5 mixed cryoglobulinemia patients with renal, neurologic, and vascular involvement

A prospective clinical study evaluated the effects of combined chemotherapy, steroids and plasmapheresis on 5 patients with mixed cryoglobulinemia with renal or neurologic and vasculitic manifestations. Treatment included prednisone (1mg/kg/day), chlorambucil (white blood cell count at greater than 3,000/mm3), and plasmapheresis (1 to 3 liters/week). There was healing of cutaneous ulcers (3/3), improvement in renal function (4/4), and diminution of purpura (2/2), but little improvement in peripheral neuropathy. Complications included leukopenia, perineal ulcers, and osteomyelitis.

Antiidiotypic activity in the IgM fractions of mixed cryoglobulins

To search for human antiidiotypic antibodies, cryoglobulins from 11 patients with mixed cryoglobulinemia, 7 of whom had evidence of prior hepatitis B virus infection were separated on Sephadex G-200. Each of the IgM, 8 of which were IgM kappa, was tested with the F(ab')2 fragments prepared from each of the IgG fractions in a solid phase assay by using binding of 125I Staph A protein after the addition of rabbit anti-IgM. Unlike rabbit anti-Fab, which reacted approximately to the same extent with all F(ab')2 fragments, the IgM varied in their binding to F(ab')2 fragments, reacting with 2 to 10 antigens. Nine reacted with their autologous antigen and in 5 instances autologous reactivity exceeded that with heterologous F(ab')2 fragments. Reactivity was not related to prior exposure to HBV. Though absorption with Cohn fraction II F(ab')2 fragments generally abolished reactivity, 1 IgM protein continued to react with nine F(ab')2 fragments and 4 others with the F(ab')2 fragment from a single patient. Even when they contained only a single type of kappa-chain, the IgM appeared to contain multiple antibodies since absorption with solid phase Fc fragments or IgG removed anti-Fc rheumatoid factor activity but failed to affect binding to F(ab')2 fragments. Five of 7 IgM were able to bind the Fv region of a monoclonal IgM kappa-protein. Some of the anti-Fab antibodies were directed against idiotypes since addition of HbsAg to F(ab')2 fragments from HBsAb-positive IgG resulted in a marked decrease in binding of the IgM fraction in 6 out of 7 studies, whereas no decrease was noted in 6 experiments with F(ab')2 fragments that were HBsAb negative. The possible existence of antibodies against other idiotypes or other determinants in the Fab region cannot be excluded.

Antiidiotypic activity in the IgM fractions of mixed cryoglobulins

To search for human antiidiotypic antibodies, cryoglobulins from 11 patients with mixed cryoglobulinemia, 7 of whom had evidence of prior hepatitis B virus infection were separated on Sephadex G-200. Each of the IgM, 8 of which were IgM kappa, was tested with the F(ab')2 fragments prepared from each of the IgG fractions in a solid phase assay by using binding of 125I Staph A protein after the addition of rabbit anti-IgM. Unlike rabbit anti-Fab, which reacted approximately to the same extent with all F(ab')2 fragments, the IgM varied in their binding to F(ab')2 fragments, reacting with 2 to 10 antigens. Nine reacted with their autologous antigen and in 5 instances autologous reactivity exceeded that with heterologous F(ab')2 fragments. Reactivity was not related to prior exposure to HBV. Though absorption with Cohn fraction II F(ab')2 fragments generally abolished reactivity, 1 IgM protein continued to react with nine F(ab')2 fragments and 4 others with the F(ab')2 fragment from a single patient. Even when they contained only a single type of kappa-chain, the IgM appeared to contain multiple antibodies since absorption with solid phase Fc fragments or IgG removed anti-Fc rheumatoid factor activity but failed to affect binding to F(ab')2 fragments. Five of 7 IgM were able to bind the Fv region of a monoclonal IgM kappa-protein. Some of the anti-Fab antibodies were directed against idiotypes since addition of HbsAg to F(ab')2 fragments from HBsAb-positive IgG resulted in a marked decrease in binding of the IgM fraction in 6 out of 7 studies, whereas no decrease was noted in 6 experiments with F(ab')2 fragments that were HBsAb negative. The possible existence of antibodies against other idiotypes or other determinants in the Fab region cannot be excluded.

Human monoclonal macroglobulins with specificity for Klebsiella K polysaccharides that contain 3,4-pyruvylated-D-galactose and 4,6-pyruvylated-D-galactose

Two human IgM myeloma proteins, IgMWEA and IgMMAY, were found to react with agar and Klebsiella polysaccharides that contain pyruvylated D-galactose (DGal). Quantitative precipitin data and precipitin inhibition studies with methyl alpha- and beta-glycosides of 4,6-pyruvylated-D-galactose showed their combining sites to be different, although each was directed against the pyruvylated-D-Gal, one reacting most specifically with Klebsiella polysaccharides with terminal nonreducing beta-linked 2,4 pyruvylated-D-Gal, whereas the other reacted equally well with Klebsiella polysaccharides that contain 3,4 beta-linked and 4,6 alpha-linked terminal nonreducing pyruvylated-DGal. Inhibition studies showed that both sites are directed toward one of the two space isomers of 3,4- or 4,6-pyruvylated DGal, the form in which the methyl group of the pyruvate is equatorial, or endo, and its carboxyl group axial, or exo, to the plane of the acetal ring. Coprecipitation studies showed the combining site of IgMWEA to be located on an (Fab')2 fragment and not on the (Fc)5mu fragment. The monoclonal peak in the serum of IgMMAY was specifically precipitated by Klebsiella polysaccharide. Myeloma proteins with specificities of this type may occur with reasonable frequency in humans and may be a consequence of clonal expansion from inapparent infection, carrier states, or disease produced by various Klebsiella organisms.