Intrathecal immunoglobulin synthesis. Comparison of various formulae with the 'gold standard' of isoelectric focusing

The recent introduction of a further new formula for calculating intrathecal Ig synthesis led us to compare the results of calculations obtained when using it and certain other older formulae with those of isoelectric focusing (IEF), since only the latter proves the intrathecal synthesis of oligoclonal proteins. On comparison, it was found that the results produced by the usual formulae were, without exception, inferior to those of isoelectric focusing. By using Receiver Operating Characteristic (ROC) curves, it is shown that calculations with the Reiber formula agree best with IEF. Virtually the same results are obtained with the "ln IgG index + 1" and "IgG index".

The HAF enigma: origin and clinical consequences of the appearance of high alkaline fractions on isoelectric focusing patterns of cerebrospinal fluid

High alkaline fractions (HAF) are irregularly present on isoelectric focusing (IEF) patterns of cerebrospinal fluid (CSF). Therefore, this phenomenon was studied retrospectively in more detail. First, the appearance of HAF in time was recorded and attempts were made to discover a relationship to the biochemical parameters of CSF. No such relationship could be established, nor could any effect of age or sex of the patients or any correlation with ambient temperature or clinical diagnosis be shown. Finally, we have shown conclusively that the cause of this random appearance of HAF can be found in the collodion bags used to concentrate the CSF. This irregular feature of the collodion bags also produces a rise in the frequency of appearance of oligoclonal bands on IEF, probably by blocking the passage of proteins. We conclude that the CSF contains protein material, and that the passage of this through the collodion filters during CSF concentration depends on the regularity of composition of the filters used, occasioning the presence (or absence) of a HAF. Of even greater consequence is the observation that when HAFs do not pass a certain collodion filter, other protein-like material can also be retained, leading to the appearance of oligoclonal bands in IEF, and causing more frequent occurrence of IEF patterns containing oligoclonal bands in CSF. Also, a slight change in the spectrum of oligoclonal bands of CSF has been found when HAFs occur. This indicates that the collodion bags do not retain all protein material in the same way.

Intrathecal Ig synthesis. Its detection by isoelectric focusing and IgG index

In a retrospective study on 999 patients, the likelihood ratios of the IgG index, Tourtellotte formula and IgG concentration in CSF and in serum, the albumin concentration in CSF and in serum, and the total protein in CSF, were compared in predicting intrathecal Ig synthesis. This synthesis was detected with isoelectric focusing (IEF). No patient was included more than once in the data collection. All patients with high IgG and other abnormalities in serum, as well as all xanthochromic and blood-tinged CSF specimens, were excluded from the study. Construction of ROC curves established that the IgG index, Tourtellotte formula and CSF IgG yield the same information: these parameters indicate the presence of intrathecal IgG synthesis. The likelihood ratio for the IgG index at a cut-off point of 0.80 for a positive test is 20; at a cut-off point of 0.5 for a negative test it is 5. For the Tourtellotte formula, it was found that the likelihood ratio reached a maximal value of 7 at a cut-off value of synthesis of 10 mg/day for a positive test. For a negative result, the formula had a likelihood ratio of 6 at a cut-off value of -5. For CSF IgG, it was found that the likelihood ratio was 4 for a positive test with a cut-off value of 0.1 g/l. For a negative outcome, the determination of CSF IgG is only meaningful at a very low cut-off value (0.03 g/l). The other parameters studied (serum IgG concentration, albumin concentration in CSF and in serum, and total protein in CSF) showed a likelihood ratio equal to 1. It is concluded that only the IgG index, the Tourtellotte formula and the CSF IgG concentration have predictive value for intrathecal Ig synthesis as recorded with IEF.

Structure and expression of lck transcripts in human lymphoid cells

The murine lck gene encodes a membrane-associated protein tyrosine kinase that has been implicated in lymphocyte oncogenesis. Here we report the structure of normal human lck transcripts and the pattern of expression of these transcripts in developing thymus and in peripheral T cell subsets. The human lck gene encodes a 509 amino acid polypeptide that is closely related to the murine lck-encoded protein throughout its length. Analysis of the deduced amino acid sequence of human p56lck demonstrates that an amino-terminal domain, widely divergent among the seven known src family members, has been conserved between murine and human p56lck, and thus probably includes sequences crucial to the lymphocyte-specific function of this molecule. Human lck transcripts were detected in CD4+ and CD8+ T cells, in partially purified B cells, and in Epstein-Barr virus-immortalized B cell lines, but not in monocytes, granulocytes, or in nonhematopoetic cell types. Human lck transcripts are readily detectable in fetal thymocytes at 70 days of gestation, but not at 57 days of gestation, indicating that lck expression appears coordinately with the appearance of lymphoid cells in the developing thymus. Thus lck gene expression is a marker for cells of the lymphocyte lineage in man. We conclude that the lck gene probably participates in a signal transduction pathway uniquely present in lymphoid cells.

A lymphocyte-specific protein-tyrosine kinase gene is rearranged and overexpressed in the murine T cell lymphoma LSTRA

Protein-tyrosine kinases are implicated in the control of normal and neoplastic cell growth. We have used molecular cloning strategies to characterize a lymphocyte-specific protein-tyrosine kinase gene distinct from but closely related to src and yes. This gene, encoded by a genetic locus defined here as lskT, is rearranged and overexpressed in the murine T cell lymphoma LSTRA. Thus alterations in the structure or expression of this protein-tyrosine kinase gene may in some cases mediate neoplastic transformation. In addition, transcription of the normal lskT gene is restricted to cells of lymphoid origin. We infer that the lskT-encoded protein-tyrosine kinase may aid in transducing proliferative or differentiative signals unique to lymphocytes.

New class of limited-host-range Agrobacterium mega-tumor-inducing plasmids lacking homology to the transferred DNA of a wide-host-range, tumor-inducing plasmid

Biotype 1 and 2 strains of Agrobacterium tumefaciens were isolated from crown gall tumors of Lippia canescens plants growing as ground cover in Arizona. The isolates were agrocin 84 sensitive, did not catabolize octopine, nopaline, agropine, or mannopine, and were limited in their tumorigenic host range. One biotype 2 strain, AB2/73, showed the most limited host range; it incited tumors only on Lippia strains, the cucurbit family of plants, and Nicotiana glauca. Megaplasmids were detected in the isolates by vertical agarose gel electrophoresis. The unusual host range, as well as sensitivity to agrocin 84, were plasmid specified since they were conjugally cotransferred with plasmids from donor strain AB2/73. Correlation of deletions with concomitant loss of virulence and agrocin 84 sensitivity identified the megaplasmid pAtAB2/73d as the virulence element in strain AB2/73. The estimated size of this tumor-inducing plasmid was 500 kilobases. Axenic growth of tumor tissue incited by strains carrying pAtAB2/73d was phytohormone independent. Although the limited-host-range megaplasmid pAtAB2/73d lacked any detectable homology to the phytohormone-biosynthetic genes in wide-host-range transferred DNA (tms-1, tms-2, tmr), it showed homology to the wide-host-range virB, virC, virD, and virG loci. Therefore, pAtAB2/73d represents a new class of tumor-inducing plasmids distinguished by its large size, the absence of determinants for the catabolism of several known opines, the presence of agrocin 84 sensitivity, and its lack of homology to wide-host-range transferred DNA contrasted with its conservation of sequences from the wise-host-range vir region.