The effects of cysteine to alanine mutations of CD18 on the expression and adhesion of the CD11/CD18 integrins.

Of the 56 cysteines in the extracellular domain of the CD18 antigen (beta2 integrin subunit), corresponding ones are not found in 12 positions in the beta4, beta7, or beta8 integrin subunits. These 12 cysteines were mutated to alanines, either singly or in pairs, in CD18. All these mutants can support the expression of all three CD11/CD18 integrins. Transfectants expressing these variant integrins are generally more adhesive than the wild-type, suggesting that the cysteine residues, perhaps by engaging in disulphide bonds, may contribute to the maintenance of the CD11/CD18 integrins in a resting state.

Infertility, in vitro fertilization and congenital tuberculosis.

Congenital tuberculosis (CTB) due to maternal genitourinary (GU) TB infection is a rare occurrence, as infection of the genital tract in women generally leads to infertility. Increasing availability of assisted reproductive technology creates the potential for CTB to emerge as a significant problem. We describe five infants (two sets of twins and a singleton birth) conceived by in vitro fertilization who developed CTB. All five infants were born to mothers who had immigrated to the United States from India and none had GU TB diagnosed before the birth of their infected infants.

The clinical spectrum of toxic shock syndrome.

Toxic shock syndrome (TSS) is a recently recognized acute multisystem illness that may recur. Epidemiologic links with menstruation and use of tampons have been identified. We report the cases of seven patients (six women and one man), 12 to 31 years old, seen over nine months, who met the criteria for TSS. Four were menstruating at onset. All had hypotension, fever, erythematous rash and distal desquamation. A prodrome of myalgias and diarrhea occurred in all patients. Clinical features of the acute illness included pharyngitis, conjunctivitis, leukocytosis and renal dysfunction (7), hepatobiliary abnormalities (6), mental confusion (6) and coagulopathy (4). In three patients, examination of cerebrospinal fluid showed abnormalities. The illness progressed in three patients to adult respiratory distress syndrome and significant cardiac dysfunction. Staphylococcus aureus was isolated from mucosal sites in six. The disease recurred in two. There were no deaths. Possible transmissibility was illustrated by two patients, a married couple, with simultaneous illnesses. Pathophysiologic features of TSS suggest a toxicogenic cause. Management consists of early recognition, vigorous fluid resuscitation, inotropic support as needed, discontinuation of tampon use and treatment with antistaphylococcal antimicrobic drugs.

Successful treatment of gram-negative bacillary meningitis with moxalactam.

Meningitis caused by enteric gram-negative bacilli is relatively uncommon but is very difficult to treat despite susceptibility in vitro to many antimicrobics. A major problem appears to be poor entry of many drugs into the central nervous system. Moxalactam is an investigational cephalosporin that attains concentrations in the cerebrospinal fluid that are 15% to 30% of contemporaneous serum concentrations; moreover, it is quite active against many of the enteric gram-negative bacilli. We used moxalactam to treat meningitis caused by Enterobacter cloacae, Klebsiella pneumoniae, and Escherichia coli in four adults and one child, giving up to 100 mg/kg body weight per day by intravenous injection. The concentrations of moxalactam in serum, lumbar, and ventricular cerebrospinal fluid exceeded the minimal lethal concentrations of all causative bacteria. The patients were cured. In this small series, moxalactam, when administered intravenously as the sole agent of therapy, was effective in the treatment of meningitis caused by susceptible gram-negative bacilli.

Characterization of four CD18 mutants in leucocyte adhesion deficient (LAD) patients with differential capacities to support expression and function of the CD11/CD18 integrins LFA-1, Mac-1 and p150,95.

Leucocyte adhesion deficiency (LAD) is a hereditary disorder caused by mutations in the CD18 (beta2 integrin) gene. Four missense mutations have been identified in three patients. CD18(A270V) supports, at a diminished level, CD11b/CD18 (Mac-1, alphaMbeta2 integrin) and CD11c/CD18 (p150,95, alphaXbeta2 integrin) expression and function but not CD11a/CD18 (LFA-1, alphaLbeta2 integrin) expression. Conversely, CD18(A341P) supports a limited level of expression and function of CD11a/CD18, but not of the other two CD11/CD18 antigens. CD18(C590R) and CD18(R593C) show a decreasing capacity to associate with the CD11a, CD11c and CD11b subunits. Transfectants expressing the CD11a/CD18 with the C590R and R593C mutations are more adhesive than transfectants expressing wild-type LFA-1, and express the reporter epitope of the monoclonal antibody 24 constitutively. Thus, the four mutations affect CD18 differently in its capacities to support CD11/CD18 expression and adhesion. These results not only provide a biochemical account for the clinical diversity of patients with leucocyte adhesion deficiency, but also offer novel insights into the structural basis of interaction between the alpha and beta subunits, which is an integral component in our understanding of integrin-mediated adhesion and its regulation.