Lymphokine-activated killer activity in long-term cultures with anti-CD3 plus interleukin 2: identification and isolation of effector subsets.

Peripheral blood lymphocytes cultured in recombinant interleukin 2 during 3 to 5 days (short-term cultures) develop the ability to lyse natural killer-resistant tumor lines and fresh tumor cells, i.e., express lymphokine-activated killer (LAK) function. Phenotypic analysis has shown these cells to be natural killer cells, i.e., CD16+ and/or Leu 19+ cells. CD3+,CD16- T-cells, instead, develop very low LAK function in these cultures. We recently reported the development of long-term (up to 21 days) cultured cells with LAK activity by stimulation with OKT3 + interleukin 2(IL2). These culture conditions repeatedly resulted in a several hundred-fold expansion in cell number. Specific LAK activity on Day 14 of culture was comparable to that of 3-day LAK cultures and could be further enhanced by the addition of interleukin 1 beta, beta-, or gamma-interferon. Total LAK activity was greatly increased in OKT3 + IL2 cultures over that found in short-term cultures. Isolation of effectors mediating LAK function in long-term cultures stimulated with OKT3 + IL2 showed that both CD3+,CD16- cells and CD16+,CD3- cells tested on Day 14 of culture expressed equivalent levels of LAK activity as shown by lysis of natural killer-resistant targets, HL60 and Daudi. Further dissection of the subpopulations developing LAK activity demonstrated that, in addition to CD16+,CD3- cells, CD3+, CD4-,CD8- cells and Leu 19+,CD3-,CD16- cells also developed high LAK activity in long-term cultures with OKT3 + IL2. Further, long-term culture with OKT3 + IL2 induced increases in the numbers not only of CD3+,CD4-,CD8- cells but also of CD16+,CD3- and Leu 19+,CD3-,CD16- cells. Although there is a significant increase in the number of CD3+,CD8+ cells, neither these, nor the CD3+,CD4+ cells, mediate LAK activity to the same extent as the populations mentioned above.

Impaired release of sCD23 by activated B-cells from RA patients.

To determine the basis of a differential response among B-cells derived from rheumatoid arthritis (RA) patients and their normal counterpart to anti-CD3-activated T-cells (HUT-78 CD4+), B-cell responsiveness was measured in vitro with a focus on IgG and IgM secretion, the ability to differentiate into plasma cells, and the release of soluble CD23 (sCD23) into the culture media. In the patients with RA, plasma sCD23 levels were measured and studied to see if it related to the rheumatoid factor (RF) titer, age, sera immunoglobulin, therapy, and disease activity. Patients with RA were found to have a significantly increased level of sCD23 in the plasma when compared to control individuals, yet their peripheral blood B-cells were unable to secrete normal levels of sCD23 following in vitro stimulation by T-cells. The plasma level of sCD23 found in the RA patients correlated (P < 0.0001) with the RF titer. B-cells from the RA patients secreted significantly increased amounts of IgG and IgM after in vitro stimulation by T-cells. It appears that peripheral blood B-cells of RA patients are more activated initially and it is likely that at the time of coculture with T-cells they had already passed through the narrow window in cell maturation when sCD23 is released.

Large-scale cloning of human chromosome 2-specific yeast artificial chromosomes (YACs) using an interspersed repetitive sequences (IRS)-PCR approach.

We report here an efficient approach to the establishment of extended YAC contigs on human chromosome 2 by using an interspersed repetitive sequences (IRS)-PCR-based screening strategy for YAC DNA pools. Genomic DNA was extracted from 1152 YAC pools comprised of 55,296 YACs mostly derived from the CEPH Mark I library. Alu-element-mediated PCR was performed for each pool, and amplification products were spotted on hybridization membranes (IRS filters). IRS probes for the screening of the IRS filters were obtained by Alu-element-mediated PCR. Of 708 distinct probes obtained from chromosome 2-specific somatic cell hybrids, 85% were successfully used for library screening. Similarly, 80% of 80 YAC walking probes were successfully used for library screening. Each probe detected an average of 6.6 YACs, which is in good agreement with the 7- to 7.5-fold genome coverage provided by the library. In a preliminary analysis, we have identified 188 YAC groups that are the basis for building contigs for chromosome 2. The coverage of the telomeric half of chromosome 2q was considered to be good since 31 of 34 microsatellites and 22 of 23 expressed sequence tags that were chosen from chromosome region 2q13-q37 were contained in a chromosome 2 YAC sublibrary generated by our experiments. We have identified a minimum of 1610 distinct chromosome 2-specific YACs, which will be a valuable asset for the physical mapping of the second largest human chromosome.