UPDATE 2-Alliance Data 1st-qtr net falls on lower revenue

* Alliance net profit falls 43 percent

* Affirms full-year cash EPS outlook

* Cash earnings per share beats Wall St view

* Shares unchanged in after-market trade (Adds cash earnings per diluted share, Reuters Estimates, updates share price)

NEW YORK, April 22 (Reuters) - Business services company Alliance Data Systems Corp (ADS.N) said on Wednesday its first-quarter profit dropped, as revenue fell 4 percent.

Alliance Data's net income was 43 percent lower at $27.9 million, or 45 cents per diluted share, compared with $49.3 million, or 61 cents a share, a year earlier.

Cash earnings per diluted share in the first quarter were $1.19 compared with $1 in the year-ago quarter, beating analysts average expectations of $1.10 per share, according to Reuters Estimates.

The company said it expects to meet its full-year cash earnings per share outlook of at least $5.15, which would be 17 percent higher than a year earlier.

Alliance shares fell 2.56 percent to $40.68 during the regular session on Wednesday. Shares, which had fallen by as much as 1.7 percent after the report, moved back to $40.68 in post-market trade.

(Reporting by Lilla Zuill)